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1941 Buick Limited Limousine


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2 hours ago, Spinneyhill said:

What about a longer bolt with a tube to push on the washer(s) and tighten the bolt onto the tube, outside the pipe? The tube might have a sexy shape to accommodate the pipe.

Cool idea, that's thinking well outside the box.

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6 hours ago, Spinneyhill said:

What about a longer bolt with a tube to push on the washer(s) and tighten the bolt onto the tube, outside the pipe? The tube might have a sexy shape to accommodate the pipe.

 

That's a great idea! I'll try that if those titanium bolts don't fit. I'm sure I could find a way to make it look right. It's mostly hidden under the carburetors anyway, but perhaps something just long enough would work. Thanks for thinking for me--sometimes you get too close to a problem and you can't see any other alternatives. Nice!

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26 minutes ago, JohnD1956 said:

Is it out of the question to grind a little off the intake manifold surface here?

Yes. This is cast iron, which has low tension strength. The engineers made it that size for a reason; mess with it at your peril. The heat box removal will also have weakened the manifold but if it remains bolted in place as intended, not holding up the exhaust pipe, hopefully it should be safe. Tensile stress induced by thermal changes will be the main threat.

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  • 2 weeks later...

That's a big negatory on the titanium bolts, good buddy.

 

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Close, but no cigar

 

The problem here is that the head takes a 7/16 wrench while the others took a 3/8. That extra 1/16 was just enough to make it impossible to fit a wrench in there. The bolt I need for this application simply does not exist and I have spent more than $40 just on bolts to prove it.

 

So I figured I'd try Spinnyhill's suggestion of making a sleeve of sorts to move the head of a longer bolt to the outside of the header tube. Unfortunately, after going to the metal store and buying some 3/8 thin-wall round tubing and some longer stainless bolts, I realized that if there's no clearance for a bolt head, there's no clearance for a tube, and with the intake in place, no place for the bolt head. Great idea, but it sadly won't work. Another $30 wasted. Dang.

 

That left just one option: beat the hell out of the tube with a hammer. So I did. And eventually there was enough clearance to tighten that titanium bolt using an open-ended 7/16 wrench. I think I might do a little more hammering just to make it a little easier to install the whole thing (remember, I'm doing this mock-up on an engine on a stand; it's going to be ten times harder to do this inside the engine bay). Ultimately I was able to make it fit and install all the hardware, spacers, gaskets, and various other parts in their correct places.

 

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Finally able to mount all the manifolds and secure them using
the hardware that I'll be using in the final installation. I made some
notes to help me get it right when installing it inside the car because
I discovered the order of operations is critical to making it all fit.

 

I also wanted to mock up the carburetors just to make sure they fit properly and to work on details like the extra stove pipe for the rear carburetor's choke as well as determining what hardware I'll need to mount both carburetors on the intake manifold. As you'll recall, I plan to use two front carburetors and run them in parallel rather than sequentially. That means a different linkage, provisions for two choke mechanisms, and making a few other changes that I'll show below.

 

Fortunately, I have a large cache of spare 1941 Buick parts, including this rather scruffy dual carb setup from a small series engine. I bought it to install on my '41 Super convertible, but I [very regrettably] sold that car a few months ago so I don't really need it. I figured I'd scavenge a few parts from it, including the front carb (a Stromberg like the Limited) and the flapper valve that lives under the rear carburetor. I used a second Stromberg I already had sitting on the shelf so I  have two front carbs for my mock-up, I removed the long mounting studs for the air cleaner assembly, plus the air cleaner assembly itself (they're identical for large and small series). I have about a half-dozen air cleaners, but this one was sitting there already so I used it even though it's pretty rusty. '41 Buick guys will note that this air cleaner does not have provisions for the PCV tube from the valve cover to the air cleaner, suggesting that it's from a late production car.

 

02-09-19no3.thumb.jpg.3298cf41fb2fdefacdf602ea7b2f12ea.jpg 02-09-19no4.thumb.jpg.3eef1cb8c878a88ea149476d82f8a7e5.jpg 02-09-19no5.thumb.jpg.0ca080f0b534ff734c7683bd709289cf.jpg
Spare dual carb setup donated its flapper valve for the rear carb. Pretty rusty inside and the flapper is frozen, but that doesn't matter for
my purposes. I also cribbed the long mounting studs for the air cleaner assembly and the front carburetor just for mock-up purposes.

 

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Just a small digression to show how the stove pipe for the choke is configured on the original manifolds. You may recall when I was first
fabricating the headers that I added a second stove pipe to feed exhaust heat to the rear carb. This is what it looks like on the original.
I may re-use the stove pipe itself, although I have two new ones that I bought from CARS so that might be the better choice. Note that
the stove pipe passes through the manifold and doesn't actually send exhaust gasses into the choke mechanism, just heated air. My

setup should do roughly the same thing. My chokes might be a little slower to react, but it shouldn't be a problem.

 

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I threw the flapper valve in the sandblast cabinet to clean it up a bit, then removed the throttle plates and shaft.

With the stock setup, the rear carb only comes online during large throttle openings, which pulls the flapper

valve open--in this way, the rear carb stays offline until needed (it doesn't have an idle circuit or a choke).

My setup will have both carburetors flowing all the time so there's no need for the flapper. However, the

rear carb sits higher than the front (the engine slopes downward towards the rear) so keeping the housing 

as a spacer ensures everything lines up correctly once it's mounted on the engine.

 

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My only concern is how to close up the shaft holes. I don't want
to braze them since this is just a pot-metal casting and I don't
want to put too much heat into it. I'm thinking maybe some epoxy
putty, although I worry about it coming loose and getting sucked
into the engine. Any suggestions?

 

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Then I mounted all the various parts on the intake manifold. I have new phenolic spacers from 
Bob's Automobilia, new gaskets, and I'll get some new mounting studs for the carburetors. I'll

probably re-use the long air cleaner studs that are already on the Limited since they're in far

better shape than these, but they make it easy to mock everything up.

 

I ran out of time today but I'll get the stove pipes in place and maybe mock up the linkage, although it'll probably be easier to do it in the car. I'll also remove the starter switch from both carbs since my car doesn't use the foot pedal starter system (I had it hooked up but found that the car starts almost instantly with the throttle closed so I went back to a push-button under the dash). I may keep the front one in place just in case, but we'll see how much room there is for the stove pipe. It should technically fit like stock. I'll decide later.

 

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I guess with the intake manifold, carbs, and air cleaner all in place,

the deformed header tube won't be terribly noticeable. I can live with it.

 

Next steps will be mocking up the chokes, gathering the carburetor mounting studs and other hardware that I need, and rebuilding one of these spare Strombergs to act as the rear carb. Then we take the car apart, install it all under the hood, and start fabricating the exhaust system. I'm going to use stainless just because I don't want to do it again. I've also decided to use 2.25-inch tubing rather than 2.5-inch simply for clearance purposes--I don't think this particular engine flows enough air volume that it will matter and it's still a significant step up over the stock 2-inch exhaust system (in fact, the step from 2.0 to 2.25 inches provides more flow improvement than the step from 2.25 to 2.5). I'll have to measure how much room I have under there for a GIANT muffler to keep it nice and quiet, then have that custom made by one of the big exhaust shops. I'll use an original-style round muffler, just the biggest one that will fit. And then I'll be done with this project.

 

I'm sure it will be just that easy, right? LOL!

 

 

 

Edited by Matt Harwood (see edit history)
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Sorry the tube idea didn't work. My next idea is too late, but what about a "waisted" bolt? Make it out of hex rod, cut the bolt on one end with a pseudo-bolt head, then turn a waist into the rod above the pseudo-bolt head to clear the pipe. The true bolt head would be outside the pipe. The pseudo-bolt head would seat against the retaining washer and spring washer on the manifolds to do the retaining job.

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You know what's completely awesome? Our shop's proximity to Summit Racing. I can order a part early in the morning, and 7 times out of 10 it shows up that afternoon. Or if I order it the night before or over the weekend, it's there first thing the next morning. No charge, no expensive overnight shipping, nothing. Need something? Bam! It's there. I ordered these mounting studs at like 10:30 SUNDAY NIGHT. 10 AM Monday morning, they're in my hand. Awesome!

 

Nothing exciting about the studs themselves, of course. They fit, although the longer ones are a touch too long and the short ones are a touch too short, but neither really affects their function. Meh, I can tweak how far I screw the studs into the manifold--a little Lok-Tite and they'll stay put.

 

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New studs for the carburetors. 

 

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I'll use lock washers to secure the carburetors. Note the phenolic spacers to protect the carbs 
from heat (which will be a non-issue with the exhaust manifolds decoupled from the intake)

 

I was also thinking about the throttle linkage. I have some aftermarket linkage parts that will work, but they look... aftermarket. I was thinking I could use some threaded rod to make it work instead and somehow incorporate the original linkage into the assembly to keep it looking as stock as possible. Original dual carb throttle linkages are next to impossible to find and I don't really want to cut up a good one, so maybe I'll try to find something that might work from a single carb car. I'll figure it out.

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  • 3 weeks later...

It's March and I'm suddenly running out of winter to get work done. Time to kick this exhaust thing into high gear and get it done so I'm not without it when the weather breaks next month. So I removed the intake and exhaust systems from the car this afternoon in preparation for installing the new manifolds. Fortunately, I did this job about four years ago so all the hardware was new and came apart without a fight.

 

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Start here. Looks decent and hopefully will run just as well when I'm done.

 

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Disassemble. Fortunately, I just installed all this stuff a few years ago and it came out without a fight, including the manifold studs.

 

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Ready to install all the new hardware.

 

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Test fitting the header. No issues. Note that it even fits pretty well
against the stock exhaust system. Not bad for a guy who is making
this up as he goes along...

 

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Before the test fit, Melanie pointed and worried that the header
might not clear the indentation in the firewall. Plenty of room. Whew!

 

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Old stuff is totally cooked even though it's not very old. Copper gaskets disintegrated and crumbling and the

manifold is cracked. Not broken into pieces like this car's original manifolds, but 100% done nonetheless.

 

I pulled all my mock-up parts off the engine on the stand and got my hardware organized for the installation (studs, washers, lock washers, lock nuts, etc). I cleaned up my custom spacers and square washers in the blast cabinet and gave them a fresh coat of high-heat paint so they look good because they got pretty beat up during the mock-up stage. I also ordered a fresh set of RemFlex gaskets, again because those I used for the mock-up were pretty beat up. They're reusable but they've been torqued and removed about 20 times so fresh ones are a smart decision--I don't plan on doing any of this ever again. I'll block off the ports on the head and clean up the mounting surfaces, then get started with the installation when the gaskets show up on Tuesday or Wednesday. I'll need Dr. Francini's help to get that manifold and header hanging in there. On the stand is one thing, but assembling it in the engine bay is a different task altogether.

 

My plan is to simply reinstall the existing carburetors and linkage for now just to get it running so it can go to the exhaust shop, then I'll do the carb swap and linkage upgrade and final tuning once it's complete. However, when I pulled the front carb currently on the car, I noticed that the choke plate was wide open and there wasn't any spring action--that choke is not working. At room temperature, it should be closed. I'll take it apart and see what's going on in there. I have a rebuilt Stromberg on the shelf that should have a functioning choke so that one will go on the front and this front carb will move to the back.

 

I also ordered a stainless muffler from Classic Exhaust, the biggest one that will fit: six inches in diameter and 42 inches long with 2.25-inch inlet and outlet. I told them I want it quiet, so we'll see what I get in the next week or so...

 

Time to make this sucker RUN!

Edited by Matt Harwood (see edit history)
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  • 2 weeks later...

I'm in the home stretch on the exhaust project--the header is installed along with the rest of the intake system. As soon as I get my custom-built muffler, it'll be off to the exhaust shop to get the exhaust system finished. With luck, it'll be ready to roll to our first event in late April. 

 

Installing the header on the car was easier than expected--almost easier than it has been working on the stand. Perhaps it's all the practice that I had putting it on and tearing it off repeatedly. Whatever the case, the installation was straightforward and went without a hitch--a rarity in the old car world. I started with new manifold gaskets from Remflex--I'm totally sold on these gaskets (I will be having them make a custom set for my V12 Lincoln as well). I installed fresh studs in the head with a few drops of red Lok-Tite so they'll stay put even with the heat of combustion in the head, then I hung the gaskets in place. That problematic bolt I struggled with needed to be in place as the intake/exhaust assembly was eased into place as a unit so that's what I did. It lined up surprisingly easily and I put a few turns on the bolt to make sure it was threaded properly.

 

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Studs were each installed with a small drop of red
Lok-Tite. No need to use a lot of it, this is plenty.

 

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Once the studs were in place, I hung the Remflex gaskets. Note how much thicker they are than
regular gaskets (and remember how those copper gaskets I used last time just fell apart).

 

Once I was sure it was going on straight, I installed the rest of the spacers/square washers/washers/lock nuts in place and snugged them down finger-tight. For the studs, I'm using lock nuts that are slightly deformed to grab the threads--they won't back off and do not need lock washers. I did, however, use some hardened washers that will help distribute the torque over a larger area and won't distort. Then I gradually snugged them all up working from the center outwards in both directions. The center and end positions on the header were secured with small bolts, lock washers, and hardened washers, as were the two titanium bolts near tubes 4 and 5.

 

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Center positions were secured with small-head bolts, lock washers, and hardened washers.
Note the custom-fitted square washers and spacers to make it all fit properly.

 

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Outer positions with studs were secured with crush nuts and
hardened washers, plus square washers and spacers. The round
mark on the nut indicates that it's a locking crush nut.

 

After all the fasteners were in place, I gently torqued them to about 30 lb.-ft. Remflex recommends 20 but with that much cast iron hanging off the side and the difference in materials, it seemed prudent to try to get them as snug as possible without over-torquing the assembly. If previous experience is any indicator, I don't expect any problems with leakage along the head flange. 

 

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All fasteners torqued and manifolds secure. Looks good, doesn't it?

 

Once the manifolds were secure, it was simply a matter of reinstalling the carburetors and air cleaner. I used more Lok-Tite on the carburetor studs and recycled the old phenolic spacers since they were still in good shape. For the moment, I simply reinstalled the existing carburetors and left the progressive linkage in place. I also reinstalled the original flapper valve under the rear carburetor, but I noticed that it was binding pretty badly--I wonder if it even worked? It took quite a bit of effort to open it, more than just engine vacuum could overcome. I wonder if my rear carb even was doing anything at WOT? This big car was always impressively fast, but if that rear carb wasn't working properly, I was probably down 20 or 25 horsepower--significant on an engine that makes 165. I continue to believe that this engine has been modified--perhaps some extra compression and a larger cam. It's just too strong to run this well with such a handicap. That also bodes well for the future modifications once it's finished. 

 

Once the exhaust is done, I'll have to re-tune the car anyway so that's the right time to change to two front carbs and synchronous operation, which will surely add considerable horsepower--fellow board member Lawrence Helfand says his '41 Century is notably peppier with both carbs running all the time. For now, I just need it to run well enough to ensure the exhaust doesn't leak.

 

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Install the carbs (note air cleaner support studs)...

 

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...and install the air cleaner assembly.

 

Even the collectors will blend in. I designed the headers to work with a stock exhaust system, but they use a 3-bolt flange where the stock exhaust uses a 2-bolt flange, so I couldn't connect the existing exhaust system to the headers. I was sorely tempted to fire it up anyway, but decided that would be a mistake. I'll wait until there's a full exhaust system on it again before I fire it. But with the correct flanges, a stock exhaust system will fit. My system won't be too different from stock, with a Y-pipe, 2.25-inch tubing, and an oversized muffler, with the primary difference being that it will be 2.25-inches from front to back rather than stepping down to 2-inches at the muffler. Again, nobody will notice the slightly larger tailpipe but it might improve flow a little bit. My primary concern is quiet, but these upgrades will surely make a difference in performance.

 

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Collectors are designed to fit stock exhaust but since the flanges
are different, I could not hook it up. A test fire will have to wait
for the new exhaust system.

 

I'm extremely pleased with the finished product. It fits well, and had I been a little more careful with how I oriented tubes #4 and #5, it would have been an effortless installation. Better yet, it blends in and doesn't call attention to itself--most folks probably won't even notice that it's there. Even the fresh paint on the intake manifold matches the engine pretty well. Check out these before and after photos:

 

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It'll be going to the exhaust shop in the next week or two. It's exciting to be this close to the end of this project (which started about a year ago). I'm also very eager to see how it sounds and feels with a quiet exhaust and perhaps even a bit more horsepower. The fastest car in the local CCCA is about to get even faster...

 

 

Edited by Matt Harwood (see edit history)
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1 hour ago, Matt Harwood said:

The fastest car in the local CCCA is about to get even faster...

 

Anticipating a performance report!  Hope it's all you expected and then some more! 

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Nice work and hopefully you now have a lasting repair.  Will you need to re-torque those manifold bolts after a few run cycles with those Remflex gaskets?

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2 hours ago, EmTee said:

Will you need to re-torque those manifold bolts after a few run cycles with those Remflex gaskets?

 

Remflex says they don't ever need to be re-torqued. They do compress quite a bit when you torque them down which I presume helps keep things tight, kind of like a lock washer spring underneath the flange. Just the same, I put a wrench on them now and then just to be sure. It never hurts, right?

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  • 5 weeks later...

It took a little longer than expected, but I finally got my custom-made stainless muffler from Classic Exhaust up in Geneva, Ohio--Melanie woke up early this morning to make the 1.5-hour drive each way to pick it up and surprise me (that's just one of the many, many ways in which she is totally awesome).

 

The shop manual says the Limited uses a 48-inch muffler but I just can't see how it could possibly fit inside the frame; every dimension I measured says 42 inches is the largest muffler that will fit unless it's at some wonky angle. Even at 42 inches, it's still five inches longer than any of the other 1941 models' mufflers and I requested that it be extra quiet, so we'll see what happens when both carbs and the headers are exhaling through it. I plan to use 2.25-inch stainless tubing throughout (factory is 2.0 with a 1.75 outlet--yeesh!). I have some vintage decorative exhaust tips that I have been using on the car, but I'm going to have the exhaust shop polish the last 12 inches or so of exhaust pipe and trim it so it is just past the bumper and put a simple 45-degree angle cut on it. It might look a little racy (that's exactly what my 5.0 Mustang uses), but then again, this car is going to BE a little racy when this project is done. I hope to get it to the exhaust fabricator (Tim Shaffer Design-Fabrication-Welding in Mantua, Ohio) in the next few days and hopefully Tim won't need long to create a simple exhaust system like this. Then there will be a few weeks of tuning and tweaking and then we'll hit the road and see what it'll do. Very exciting!

 

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We'll see how the big guy sounds with a giant muffler and slightly oversized pipes. Muffler is mostly a straight-through design with a
small restrictor to force some exhaust gas through the baffles. I requested extra quiet.

 

 

Edited by Matt Harwood (see edit history)
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  • 3 weeks later...

Delivered the Limited to Tim Shaffer Design-Fabrication-Welding in Mantua, Ohio last week and he's started on the entirely new exhaust system. Getting it into his garage was a bit of an ordeal, since it's uphill from where we took it off the trailer. Fired it up and let it run through the open headers--woot! The thing sounded like it wanted to eat your children!

 

We're using 100% stainless and while it will be a close approximation of the original system, we're going to take some liberties with routing and configuration just to make it fit better. He's already got the old system out and is mocking up the new system starting with locating the muffler amidships. He's promised to send photos as he works, and he's only 20 minutes away, so I might run down there when he gets closer to the finish line and get some better shots. I feel like a kid and it's December 19th, and Tim is Santa Claus!

 

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Old system isn't quite correct and uses an
under-sized muffler, but it sounded OK when
the manifolds weren't leaking.

 

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Mocking up the new system, starting with the new stainless muffler and working from there. New
stainless collectors on the headers are the foundation--three bolts will be better than the factory's
two for holding everything in alignment. Remflex gaskets will seal it up.

 

I'm ready to start driving, the weather is warm and dry and the sun is out. Unfortunately, everything I own personally is laid up and the Limited is the closest to being ready to go again. The '35 Lincoln is obviously not going to be ready any time soon and the '29 Cadillac needs its springs rebuilt, which would have been done by now except that stupid Lincoln is sucking up most of my resources. My business (which is technically me) owns about 30 other old cars, but there's a difference between the cars I own (I love them) and the cars I sell (they're just things to sell) so it's not quite the same thing. Even this exhaust system is a stretch, as I'm sure it'll be somewhat expensive. Tim hasn't given me an ETA for completion simply because he doesn't know how long it'll take to get the stainless he needs, but it should be ready to go in time for the tour at the end of this month (May). I'm extremely eager, this project has taken the better part of a year.

 

Tim really does some beautiful work--if you're in northeast Ohio and need exhaust work that looks like art, give him a call. Check out this 1960 Impala he finished recently:

 

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Edited by Matt Harwood (see edit history)
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  • 2 weeks later...

 That is really some neat set up, Matt. She's going to be even more awesome than ever. My '41 seems to be one of the few with its' factory manifols stil in good order, but if I have to replace them, that sounds like the way to go.

Hope to see it sometime. I plan on going to this year's National, and next year's is very close to me, so I'm hoping to make that one as well.

 Thanks for all the great pictures!

 Keith

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Another update from Tim at the exhaust shop and he's doing beautiful work. I'm almost thinking the exhaust system is going to be too nice. Look at that Y-pipe! He'll be finishing the tailpipe shortly, then welding everything together. I am getting very excited.

 

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Oh, and I also picked up a correct speedometer drive, which should correct my wildly inaccurate speedo:

 

s-l1600.thumb.jpg.6e0aa02ab7f6c68caf6b3d3cf9d1df37.jpg
NOS speedometer drive gear should help correct my
very inaccurate speedometer.

 

I believe my engine and transmission are from a 1941 Roadmaster, and my speedometer has always read about 8 MPH slow (if I park the needle at 50 MPH, I'm going 58, which is pretty easy for driving on the highway). I can live with that, I suppose, but this little device should correct that issue. To compensate for the different gear ratios and tire sizes, they used different driven gears with different numbers of teeth on these speedometer drive assemblies. The cars with short gears have more teeth while the high-speed cars like the Century with 3.9 gears will have fewer teeth. Here's a chart from the '42 service manual showing the various configurations:

 

SpeedoGears.thumb.jpg.131c6764fd96efb97862610081bdac0e.jpg

Chart from the '42 Buick service manual suggests that a 20-tooth drive unit should
be close to accurate for my car with 4.20 gears and fairly tall tires.

 

This chart suggests that the '42 90 Series used 4.55 gears while the '41 uses 4.20 (no idea why they would change it--that's a lot of tooling for not many cars and a pretty small difference in performance) but I think this unit should be close enough. I'm betting my car has a 19-tooth unit it it, while this is a 20-tooth drive unit, so it should be just about right given that the '42 Roadmasters have 4.1 gears. Even if it's not perfect, it should be more accurate than whatever I have.

 

I'm eager to get the car back and get busy on some carburetor tuning, too. I have some linkage parts that I've been buying that will look more authentic than the aftermarket stuff from Summit Racing, but it'll take some fabrication to make it work correctly. I also have a spare front carb that I'll be installing up front and moving the existing front carburetor to the rear. I'm hoping to see a nice bump in performance as well as fuel economy with the carburetor and exhaust upgrades, and if I'm lucky, maybe even a smoother idle. The headers might be a little louder than the cast iron manifolds in terms of ambient noise, but I'm hoping it's negligible from inside the car. Heck, as long as that maddening tick-tick-tick-tick is gone under acceleration.

 

Still a long way to go...

 

 

Edited by Matt Harwood (see edit history)
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1 hour ago, Bill Stoneberg said:

Matt, I am glad you are still on the forum and still messing with cars after the fiasco with the Lincoln.

 

What Lincoln? I don't own any Lincolns...

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  • 2 weeks later...

Tim called today and said he was ready to do an exhaust check to see if it leaks, so Melanie and I headed over to his shop after work. The system is almost done, pending a few finish welds and mounting the hangers, but he wanted to make sure it sealed up properly before he made anything permanent. I have to say, I'm extremely impressed with his work, which is obvious. The guy is a perfectionist. For example, I asked him to polish the last 12 inches of the tailpipe, which he did, but he hadn't yet given it the final buff when we got there. I told him not to worry--making it perfect would make it stand out too much against the driver-grade Buick's everything else and it looked pretty good as-is. I got the impression that he wasn't happy that he didn't get the chance to buff it to perfection. And just look at those welds! The guy is an absolute artist.

 

Check out how it looks as of today:

 

5-28-19-12.thumb.jpg.ff62cec6db36d6489aeeed01cbf123f2.jpg 5-28-19-11.thumb.jpg.a3f074ce059b4cf0a62235d9662d1812.jpg
That Y-pipe is a work of art. Plenty of clearance for shift linkage. Obviously the factory
couldn't afford the time to make it look like this, but it sure is pretty!

 

5-28-19-3.thumb.jpg.fecf254ffa5d947795f2f142dbbaa48b.jpg 5-28-19-2.thumb.jpg.99e395935b812203aefec8f2274960e1.jpg 5-28-19-1.thumb.jpg.abc86b91aaf4ea97fdef972d5c10a21c.jpg

Intermediate pipe fits neatly through the frame and connects to the muffler. I told Tim
to go ahead and drill holes for hangers anywhere he wants, it won't hurt the frame.
I just don't want any rattles. Since it's stainless, it should last virtually forever.

 

5-28-19-4.thumb.jpg.9835640413cf5d266e9e32f617f02eb6.jpg 5-28-19-5.thumb.jpg.b20403c0ac366c295e5d972a5b046d90.jpg 5-28-19-7.thumb.jpg.dafae5432527d933ec54c64b19dfdab2.jpg
Over-sized muffler fits neatly in the original spot. Extra hangers insure it won't

rattle or clunk like my old system did.

 

5-28-19-8.thumb.jpg.763186ba88267a659dcaf4b5d3305714.jpg 5-28-19-6.thumb.jpg.ec66f4865302cfbf5f72e9bfb3076b45.jpg

Tailpipe is a bit more complex than OEM but fits far better.

 

5-28-19-10.thumb.jpg.35004503ac5e82f7ee679d79b5d33544.jpg 5-28-19-9.thumb.jpg.c42a160749313a8930a646384bd7183f.jpg

Tailpipe with angle cut, polished (but not well enough for Tim's liking),

and neatly tucked just below the bumper. It's bigger than stock but
perhaps nobody will notice. Not right away, anyhow...

 

5-28-19-13.thumb.jpg.f45bb3aacb98d94a73a73b9987f779ba.jpg
Just check out the beautiful radiused edge Tim put on
the end of the tailpipe! I'm incredibly impressed
by his craftsmanship.

 

So it looks pretty, how does it sound? Tim wasn't too keen on firing the big guy without me, so I climbed in and he put the lift back in the air so he could check the joints while it was running. I let the fuel pump run for a few seconds, hit the button, and it--as always--fired instantly. And the sound was COMPLETELY different! So smooth. No growl-tick-tick, no shuddering and rattling from under my feet as the muffler hit the frame, nothing. Just a smooth hum. I revved the engine a bit and it stayed smooth--it had the same voice, but it was like all the congestion in the big guy's throat had cleared. At idle, the loudest thing was the water pump, whose bearing is a little chattery. No exhaust leak, no tick-tick-tick, nothing but an expensive-sounding hum from the tailpipe. Nice!

 

Why yes, there is a video:

 

 

 

I will say that it didn't idle as well as it usually does, and I attribute that to both the better-flowing exhaust and the fact that I just threw the carbs on there to get it running. It will obviously need some extra tuning, and I'm going to save that until I have both carbs mounted and running synchronously. Tim thinks he'll be done tomorrow or Thursday, so hopefully I'll be able to spend some time tuning it in the next week and getting back on the road!

Edited by Matt Harwood (see edit history)
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Matt.......tune it using a five gas machine. With the overhead valves you will get true and accurate readings. Looks and sounds good.

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Got word today that Tim is finished with the exhaust system, so I'll go pick it up first thing in the morning. I was secretly hoping to have it Friday so I could work on it over the weekend, but no dice. I'm not the kind of guy who asks people to hurry up or put a deadline on things, especially when it's custom work. So it's done in a little under a month; I'm OK with that.

 

In preparation, I went out to the storage facility where I have my '41 Century and gathered up a bunch more stuff (the goal being to bring the entire Century back to the shop and someday get back to work on it). So many treasures! What I was really after, however, was a set of carburetors I rebuilt when I first started working on the Century. They've never been used and were professionally rebuilt at what I seem to recall was great expense. It's my plan to use the rebuilt front carb as the front carb on the Limited, then move the Limited's current front carb to the rear position. I'm going to see about repairing that carb's choke but it otherwise works quite well. 

 

Carb1.thumb.jpg.fc7017876d139a3c0dc7ac07262fec6e.jpg Carb2.thumb.jpg.8257eb4d098c7dd255268e55779c563f.jpg Carb4.thumb.jpg.ac6a499e228fb4fee9e013f6cf4a3cb0.jpg
Beautifully rebuilt Stromberg carb will become the Limited's new front carb. My car doesn't
use the foot-pedal starter so I may remove the switch, although it doesn't hurt to
leave it in place disconnected just in case I change my mind later.

 

Carb6.thumb.jpg.d3c7e6349360cf245ac52c6fad7694a5.jpg
I also found another stove pipe fitting for the
choke, but I also have a kit so I may save this
one for the Century instead.

 

Other stuff I found: seven stainless rocker moldings (so I can cut a few up and make correct-looking replacements for the Limited), a FOG LIGHT switch and knob, an NOS windshield washer system, not one but TWO NOS clocks, a full set of NOS gauges, three radios (one of which is restored), and lots of trim pieces. I don't know how much or how little I'll use on the Limited, since most is intended for the Century, but I have about a half-dozen Stromberg AAV carbs laying around, so I can always rebuild another one for the Century when I need it. 

 

The plan is to drive the Limited back the 10 miles from Tim's shop tomorrow morning. It may be cooperative, it may not, but either way there's going to be some tuning to do with the modifications I've made. I'll be working hard on getting it back into shape for next Sunday's Buick-Olds-Pontiac show.

 

Let's see what happens...

Edited by Matt Harwood (see edit history)
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22 minutes ago, Matt Harwood said:

Got word today that Tim is finished with the exhaust system, so I'll go pick it up first thing in the morning. I was secretly hoping to have it Friday so I could work on it over the weekend, but no dice. I'm not the kind of guy who asks people to hurry up or put a deadline on things, especially when it's custom work. So it's done in a little under a month; I'm OK with that.

 

In preparation, I went out to the storage facility where I have my '41 Century and gathered up a bunch more stuff (the goal being to bring the entire Century back to the shop and someday get back to work on it). So many treasures! What I was really after, however, was a set of carburetors I rebuilt when I first started working on the Century. They've never been used and were professionally rebuilt at what I recall was great expense. It's my plan to use the rebuilt front carb as the front carb on the Limited, then move the Limited's current front carb to the rear position. I'm going to see about repairing that carb's choke but it otherwise works quite well. 

 

Carb1.thumb.jpg.fc7017876d139a3c0dc7ac07262fec6e.jpg Carb2.thumb.jpg.8257eb4d098c7dd255268e55779c563f.jpg Carb4.thumb.jpg.ac6a499e228fb4fee9e013f6cf4a3cb0.jpg
Beautifully rebuilt Stromberg carb will become the Limited's new front carb. My car doesn't
use the foot-pedal starter so I may remove the switch, although it doesn't hurt to
leave it in place disconnected just in case I change my mind later.

 

Carb6.thumb.jpg.d3c7e6349360cf245ac52c6fad7694a5.jpg
I also found another stove pipe fitting for the
choke, but I also have a kit so I may save this
one for the Century instead.

 

Other stuff I found: seven stainless rocker moldings (so I can cut a few up and make correct-looking replacements for the Limited), a FOG LIGHT switch and knob, an NOS windshield washer system, not one but TWO NOS clocks, a full set of NOS gauges, three radios (one of which is restored), and lots of trim pieces. I don't know how much or how little I'll use on the Limited, since most is intended for the Century, but I have about a half-dozen Stromberg AAV carbs laying around, so I can always rebuild another one for the Century when I need it. 

 

The plan is to drive the Limited back the 10 miles from Tim's shop tomorrow morning. It may be cooperative, it may not, but either way there's going to be some tuning to do with the modifications I've made. I'll be working hard on getting it back into shape for next Sunday's Buick-Olds-Pontiac show.

 

Let's see what happens...

Hi Matt, You will find it takes very little heat to activate the rear choke tube. Mine is not connected to any fitting at the end and merely comes into contact with the exhaust manifold surface. I did pinch a small bit of foil shaped like a funnel at the end to gather a bit more heat. After a few cycles of warming up and cooling down I managed to adjust the pair of choke butterfly's so they were in synch. I dont use the factory cold closed setting that allows a small amount of open position. I did try it but it required more spring resistance then keeping it slightly cracked open to work properly so mine are fully closed from the start. It catchs almost immediately from cold and spins a few times when warm before starting. I recently looked at the plug color and it was the same medium cocoa colored insulator on every plug. I changed out my AC R46 plugs for slightly hotter Champion RJ12C. 

I suggest you drop off the limited for an OD install ASAP!  Glen and Bob are really fast and efficient and now have the experience of doing mine. You will love your Limited ten times more and want to drive it everywhere! I cannot get over what a difference it makes and I love my Century more then ever!   

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It's back! Picked it up from Tim's shop and drove it home. Wow, what a difference! There's obviously a lot of tuning yet to do, since it didn't want to idle very well, but once it warmed up and was on the open road, it felt fantastic. Pulled HARD through every gear and the only sounds I hear are a pleasing mechanical whirrr from up front and a distant hum from the tailpipe. At idle, it's almost silent save for a bit of a burble from out back, but it's quite faint. Perfect! There's one big booming thump that is completely gone now that the exhaust system is firmly affixed to the frame rather than wiggling around. Check out Tim's final work, including the awesome stainless hanger brackets he fabricated to hold it in place. Tim used 100% stainless on EVERYTHING, including the fasteners and brackets, so this exhaust system should outlast the car.

 

ExhaustFinal4.thumb.jpg.aa8a9df7f0fb06b1a680b78b1d1a6089.jpgExhaustFinal2.thumb.jpg.ef5159c631a5794a735645c0b0bdddba.jpgExhaustFinal3.thumb.jpg.e95a2521b7e2dc2abff3a97b68305ae7.jpg

 

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Tim fabricated custom brackets to secure the system under the car.

 

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Angled tailpipe looks awesome and mostly stays out of sight. Tim wasn't happy with the last
one so he made another. The guy's a total perfectionist.

 

The water pump under the hood is by far the noisiest thing on the car, so I guess I'll replace that sometime soon, and there's a pronounced HISSSSS that sounds like intake noise but I can't isolate it--that wasn't there before, I'm pretty sure of that. You can hear it in the video below. Not sure what it is, but I'll be taking it all apart anyway so hopefully it will be apparent. It's not awful and maybe not even something wrong, just a new sound. A lot has changed so maybe it's normal now.

 

Is it more powerful? I really can't say. It certainly FEELS stronger but the butt dyno is notoriously inaccurate and the placebo effect is very much in play. It may also be that I was willing to push it harder simply because it didn't sound like it was going to blow itself apart every time I leaned on the accelerator. It's at least as strong as it ever was, and that's with the carbs out of tune, so there's probably more in it yet.

 

I got back to the shop and did some quick carb adjustments to improve things a bit, then I shot some quick video. You can definitely hear the water pump, plus the hissing sound, but not much else. I tried to avoid the wind but it's breezy today so you can't really hear the exhaust note--it's a little snuffly anyway. I'll shoot another video once the carbs are dialed in correctly.

 

It took a little over a year to get here, but I finally crossed the finish line on this part of the project. It is every bit as good as I hoped and with some tweaking, it will get even better. I might start on the carb upgrades as soon as tonight...

 

 

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I spent the afternoon tinkering (what, you though I could resist?) and ended up changing out both carbs for the rebuilt ones I retrieved yesterday. The hissing sound I was hearing was the choke on the original front carb--no idea how there could be an intake leak there, but there it was. I disassembled it and found that there's some kind of plastic gasket between the face and the spring, and the spring had completely popped off its retaining stud but wasn't broken. I reassembled it and there's now tension on the choke, but I wonder why and how it was leaking? I couldn't find a hole. Hmmm....

 

Anyway, I pulled that carburetor and installed the rebuilt one in its place. Then while I was putting things back together, I was reminded that the butterfly flapper under the rear carb is frozen and probably always has been. I happened to have a freshly rebuilt rear carb with a working flapper so I threw that on as well. It fired right up and I did some adjusting and tinkering, but it's not quite as good as it was. I expected that. It's not bad, but the idle is a little rougher and there's a stumble off-idle. On a test drive, it popped through the carburetor, and at idle there's a snuffly sound to the exhaust with a periodic soft pop coming through. On the other hand, now that the rear carb is coming online like it should, it's definitely faster. Never mind the improvement from the exhaust, that second carb opening up properly definitely added some kick! I'm sort of thinking I should just go ahead and install the other front carb now before I do too much tuning. I need to figure out why there was an intake leak through the choke on that front carb...

 

I'm not at all surprised that it will need some extra adjusting and fiddling and some driving to get totally dialed in. It probably wouldn't be a bad idea to pull the plugs and clean them up, too. I have a friend with a 5-gas analyzer so I'm going to see if I can use it to tune the car once I have both front carbs in place running synchronously.

 

As long as I had it on the lift, I also installed my new speedometer drive gear. The one I pulled out had 20 teeth and the new one was 19 teeth, so that should have sped up the speedometer (it reads about 8 MPH slow). Easy enough to change it, but it had virtually no effect on the speedometer reading. It maybe reads 7 MPH slow now. How can that possibly be?

 

Speedo2.thumb.jpg.e0914347a58e152cd7827d2212e8738d.jpgSpeedo1.thumb.jpg.bad5f7e95d157cc97ec6912101a4185c.jpg

Speedometer driven gear is easy enough to change. Remove cable, unscrew drive unit, replace.

 

Gears1.thumb.jpg.26c95d529bef85a64ba2908057dc9e3d.jpg

New 19-tooth unit is on the left, original 20-tooth unit on the right.
Why didn't this change anything? It should have been about 5-6% difference.

 

I'm glad to have the Buick back. No other car makes me happy like this one. It's just a terrific machine. I highly recommend that you get one.

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When you are driving down the road and experiencing the pleasure of a car of that vintage and age , all the "stuff" and patience it took to get it there will be worth while.

Viewing a really neat classic car is an incredible experience, and viewing one from the drivers seat while under way is what a lot of us think of as the best possible reward as an "old car " owner.

It is the thing we recall that makes up happy when we are perhaps going through a rough time in life , especially when it comes to health. I know it was these thoughts of a great ride that kept me going last year while in recovery from heart surgery. Better days ahead because of our love and admiration for the "used cars" we cherish so much and the friendships we have made because of them.

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15 hours ago, Matt Harwood said:

I have a friend with a 5-gas analyzer so I'm going to see if I can use it to tune the car once I have both front carbs in place running synchronously.

 

It will be interesting to see the results of this upcoming tuning exercise.  I wonder whether the carbs will require re-jetting to compensate for the new, less restrictive exhaust system.  It would seem that a lean condition might be the cause of the 'pop' you observed.

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27 minutes ago, EmTee said:

 

It will be interesting to see the results of this upcoming tuning exercise.  I wonder whether the carbs will require re-jetting to compensate for the new, less restrictive exhaust system.  It would seem that a lean condition might be the cause of the 'pop' you observed.

 

I'm actually thinking it might be too rich once I have two front carbs running on there. Just one of these carbs is supposedly sufficient to fuel a 320 cubic inch Buick straight-8, but two of them? That might be too fat. I'm going to try anyway, but our mutual friend Jon (Carb King) suggests running two small-series Strombergs on a big engine is a better choice. On the other hand, Lawrence Helfand is currently running two large series front carbs on his '41 Century and his car apparently runs like a million bucks, so that's my first stop--I already have the carbs.

 

The exhaust may flow somewhat better, but I don't think it's going to be a huge factor in tuning. The headers might be a little better, the larger exhaust tubing might be a little better, the mandrel bends might be a little better, but I'm not convinced that it will add up to any significant improvement that would require re-jetting. The biggest difference is that the intake manifold is no longer bolted to the exhaust manifolds, so the carbs will run considerably cooler and I'm guessing that will be the source of most of the hurdles in getting it tuned correctly.

 

I decided last night to figure out why the choke in the original carb is inhaling air through the stove pipe, then reinstall that carb in the rear position. I did some reading on the choke and it appears that there's a piston that opens and closes a vacuum port inside the choke and since the spring wasn't connected and the choke wasn't working, perhaps that piston wasn't doing its job, either. My theories range from the fit of the stove pipe in the little heat stands I made for the headers is too tight and it can't properly inhale air (the original stove pipe went all the way through the manifold and had unrestricted air flow) to it was simply buggered because the spring wasn't hooked up and the choke wasn't working. I strongly suspect the latter simply because the newly rebuilt carb did not have the same hissing problem and the choke worked properly, albeit slowly--I'll adjust it.

 

So rather than try to get everything working with a stock rear carb, then go through it all again when I replace the rear carb with another front one, I may as well just do it all now and do the tuning once. Shouldn't be any more difficult and might even be easier with two front carbs on there--the original one ran pretty darned well. I have my vacuum gauge and inductive tach, so that will get me pretty close. I might try that tonight, although I think we have an event to attend so maybe not until tomorrow night.

 

We'll figure it out!

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6 minutes ago, Matt Harwood said:

I'm going to try anyway, but our mutual friend Jon (Carb King) suggests running two small-series Strombergs on a big engine is a better choice.

 

Yes, my take on that is that having two carbs gets the atomized mixture closer to the end cylinders (probably more to it than just that, though).  Once you have the initial tune resolved, you can accumulate some miles and check the spark plugs to see what they say.

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I took the time this evening to change out the rear carb so now I have two complete front carbs on the engine. I also hooked up a new linkage to make them operate synchronously rather than sequentially. I have to give big thanks to my friend Lawrence Helfand, who gave me all the part numbers and details on the linkage to make it easy to hook up--he's the guy who blazed this trail first and I'm just following his footsteps. Thanks, Lawrence!

 

The first thing I had to do was remove the butterfly flapper under the rear carb. Since both carbs will be working all the time, there's no need to close off the ports. You might remember that I had a spare flapper assembly from which I removed the butterflies. I had to block off the holes where the shaft used to be, so I tapped the holes for 1/4-28 screws, cut a pair of cap-head screws to length, added a couple drops of blue Lok-Tite, and screwed them into place. Ready to go!

 

02-09-19no5.thumb.jpg.48e8ff0c24e5e580c94cecf1e4fad6be.jpg Spacer5.thumb.jpg.bfd9fccad4e29bcc3fee70a445e7eebc.jpg Spacer1.thumb.jpg.2757e9eb509f2fec988acf5124bdfbda.jpg Spacer2.thumb.jpg.0696e75d4518c43b6ab92670f7c8dde3.jpg
Modified flapper valve ready to install.

 

Spacer6.thumb.jpg.d74ad9c97fa1e7599d2692500066b2a3.jpg
In place with new phenolic spacer and gaskets.

 

After I bolted the carb into place and reconnected the fuel lines, I could see how the throttle linkage would work. I had hoped to keep the original rod from the pedal assembly to the front carburetor, but the way it's designed didn't allow me to also connect the linkage between the carbs, so I installed new parts throughout. I had to shorten the link between the carburetors by about 10 inches, then re-tapped it for the heim joint and bolted it to the rear carb. The link between the pedal and the front carb was just barely long enough and I was able to secure it with a single bolt. Working the linkage, both carbs moved together. Nice!

 

Linkage4.thumb.jpg.09361248cbc653a9a2eb2bf349d59240.jpg Linkage7.thumb.jpg.dfac224f618a79033f56db2b5a371947.jpg
Connections at the pedal and front carb fit neatly and work smoothly.

 

Linkage6.thumb.jpg.41f7d935dce1e09889e114a2e7f152de.jpg Linkage8.thumb.jpg.7a61f41e29eef0d644c6036ab133c8d0.jpg
Finished linkage actually doesn't look as conspicuous as I thought it would. Carbs
work smoothly and move together from idle to WOT.

 

Stovepipe1.thumb.jpg.c42030ae53e7525a4e10ef6a1998e231.jpg
I also made a stove pipe for the rear carb's choke.

 

Once it was all hooked up, I hit the starter and remarkably enough, it fired right up. Better yet, it idled pretty well! Moving the linkage, it revved easily and didn't stumble. Nice! Without any tuning at all, it is about 90% as good as it was before, and that's a big relief. Right now, the biggest problem is the chokes: the front one is a little too tight and takes too long to open, even with the stove pipe hooked up. The rear one, which I discovered was broken when I first removed the carb, is the source of that hissing noise. I don't know why, but even with a fabricated stove pipe feeding it heat, it didn't work. So I have to figure that out before I can do any final tuning. I have some scrap carburetors laying around, so I'm sure I can crib a choke from one of them and see if it can be made to work properly. 

 

Choke1.thumb.jpg.938d8f7e8de1ee1f38d00110d6a5db23.jpg
Choke seems to be sucking air here, causing the hissing sound.
I'll have to figure it out or replace the choke with a spare.


A good night that makes me optimistic that I can make this thing run better than ever. Thanks again, Lawrence!

 

Edited by Matt Harwood (see edit history)
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Hi Matt, Make sure that rear idle screw is backed away from choke cam so it cant make contact as the front carb screw will now control the idle speed for both carbs. Also I moved pump arms to the shortest throw. Guessing you already did that!  Thanks for the kudos! Your limited with the new improved breathing is likely picking up another five hp easily. The 1952 320 with the quad was rated at 170 hp and I think it had a lower compression ratio. Dont know if they changed cam lift or duration or if hp increase was just better breathing. Might now be a 41 unlimited! 

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On 10/13/2017 at 7:40 PM, zeke01 said:

Matt: Thanks for the ride! I've always wanted to take a spin in a '41 Buick. What a comfortable ride! Just like sitting on my sofa! I am glad that you didn't ask me to help pay for the gas. Zeke

It is is like my '40 Limited , we can be talking single digit numbers for gas consumption if you push it over 50 MPH. That said, what is the value of a smile that won't go away?

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Good progress tonight, too. Before I could do any serious tuning, I had to get the chokes straightened out. The front carb was working correctly but it took a long time to open given the reduced heat output of the stove pipe on the header. The rear carb's choke was totally buggered so that's where I started. Pulled the carb and put it on the bench with a spare carb I had laying around that seemed to have a good choke. Just swap them out and we're good to go.

 

The choke is really a complex little mechanism that's more than just a bi-metal spring that uncoils as it warms up. There's also a little piston that produces a bypass when the choke is closed so the engine isn't totally starved for air when the choke is all the way closed. As it opens, the piston moves forward and the port is closed so the air can be properly metered through the venturis. Anyway, I figured that piston was stuck and that's what was causing that hissing vacuum leak. I opened up the existing choke and found that the piston moved freely. Nice! So all I did was switch the existing cover (whose spring was broken off) with the one from the spare carb that was in good order.

 

6-6-19-2.thumb.jpg.16a866ca6d17b94aaa2e91b1bf6f158a.jpg 6-6-19-4.thumb.jpg.6c1063ae9fd79eba6f111b49a0238b99.jpg
Choke cover has spring and a screen. The manual says this must be serviced as a unit so

the fact that the original was in pieces meant it was cooked.

 

6-6-19-1.thumb.jpg.412e775c3b51cb64e3b6c760a7f9eb95.jpg
Spare carb's choke was pretty gunked up, including what

appeared to be very find sand in the bottom. Odd...

 

Bolt it back together and put the carb back on the car. When I fired it, the hissing was still there, suggesting a problem was with the choke body instead, maybe a crack or a casting defect. Pull the carb again and remove the entire choke assembly on the bench. I couldn't find a defect, but I swapped choke bodies just the same after cleaning it out thoroughly with carb cleaner, then reassembled everything. I even made a new gasket between the choke and the carburetor housing since both of those in the carbs were pretty brittle.

 

6-6-19-6.thumb.jpg.262f51a23afb30d27fce318d67df7265.jpg 6-6-19-3.thumb.jpg.2f139eb4d0885e4c6ef143518278fe54.jpg
Disassembled, you can see how the little piston works (red arrow). The bi-metal spring on the cover

rests against the peg on the crank end of the little connecting rod and as it relaxes, the

opening of the choke plate pushes the piston forward, closing the air duct underneath

the right side mounting screw. That was somehow the source of my hissing sound.

 

Reassemble the carb once again, reinstall it on the engine, and fire it up. Hissing is gone! Then I spent some time adjusting the choke, which can be done by moving the cover to adjust the initial tension of the spring. The more tension on the spring, the longer it will take to relax. I wanted it to relax faster, so I reduced the tension by loosening the three screws around the perimeter and moving it in a clockwise direction two "marks." There's an index mark in the center that's probably a good setting for a stock car driven in all kinds of weather, but for this car in summer weather, it didn't need a lot of time on the choke while warming up. The manual says not to go more than two marks, so I guess that's the max.

 

6-6-19-5.thumb.jpg.bacde241ba4e41144f2e0cb0693ff107.jpg
I adjusted the rear carb choke on the bench by moving it clockwise

two marks. Red arrow is the recommended "0" setting
that should be aligned with the blue arrow for average usage.

 

6-6-19-7.thumb.jpg.cfd7c1db789e94a3a0410bfa37984730.jpg
Then I adjusted the front carb's choke while it was on the engine.
I reduced tension by the same two marks.

 

6-6-19-8.thumb.jpg.1ffcb64d6fe6ebe47fc750b56e4dd1cc.jpg
As long as I was at it, I removed the stove pipe I made yesterday
and trimmed it a bit to look more like the original. I'll paint it black
tomorrow so it blends in better.

 

All that done, I fired it up and it ran great! The chokes were still kind of slow to respond but after about 6 or 7 minutes of run time, they were wide open. Hopefully if I'm driving and not just running it at idle it'll warm up much faster. But I was satisfied that the chokes were healthy and operating correctly and it was running pretty darned well. Good progress!

 

The next step was balancing the carbs; that means getting both of them to flow the same amount of air at any given throttle opening. You might think you have them pretty close (I did) but you probably don't. I noticed that if I looked down the throat of the carb, I could see fuel flowing from the jets in the front carb but none flowing in the rear. Putting my hand over the front carb would stall the car but doing it over the rear carb did almost nothing. A-ha! It should be able to run on either carb, no problem, so obviously the rear carb wasn't pulling its weight.

 

I bought a simple little device that the VW guys use to synchronize their carbs called a Uni-Syn--it sits on top of the carb and uses vacuum to lift a little red bead inside a sight glass. On the Buick, I had to turn up the idle quite a bit just for it to register, but that doesn't really matter for the purposes of balancing the carbs. I adjusted the baffle on the Uni-Syn until I got a steady reading about 1/3 of the way up the scale. Then I moved it to the rear carb and adjusted the linkage between the carbs (which adjusted the rear carb's throttle opening) until I got the same reading. I locked down the linkage so they would move synchronously and voila! Both carbs flowing the exact same amount of air. Once they were locked together, I could reduce the idle to the proper level using just the front carb's idle screw and the rear carb would follow. I backed off the rear carb's idle screw far enough that it wouldn't affect anything--it's merely along for the ride now.

 

6-6-19-12.thumb.jpg.cc334158bbe50e1cf1f2919b8ba5cd76.jpg  6-6-19-11.thumb.jpg.4b61a69be180e84b2b068b2a9112000c.jpg
Uni-Syn device allows you to get both carbs inhaling the exact same amount for a given throttle opening.
Easy to use and precise enough for this application. I was surprised by how far off my "tuning" actually was.
Note that the rear carb's idle screw is backed way off.

 

Last step is going to be fine-tuning the mixture. I'll do that with a vacuum gauge tomorrow or Saturday. Sunday is the Buick-Olds-Pontiac show and the Big Guy is definitely going to be there.

 

 

 

Edited by Matt Harwood (see edit history)
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2 hours ago, Matt Harwood said:

Good progress tonight, too. Before I could do any serious tuning, I had to get the chokes straightened out. The front carb was working correctly but it took a long time to open given the reduced heat output of the stove pipe on the header. The rear carb's choke was totally buggered so that's where I started. Pulled the carb and put it on the bench with a spare carb I had laying around that seemed to have a good choke. Just swap them out and we're good to go.

 

The choke is really a complex little mechanism that's more than just a bi-metal spring that uncoils as it warms up. There's also a little piston that produces a bypass when the choke is closed so the engine isn't totally starved for air when the choke is all the way closed. As it opens, the piston moves forward and the port is closed so the air can be properly metered through the venturis. Anyway, I figured that piston was stuck and that's what was causing that hissing vacuum leak. I opened up the existing choke and found that the piston moved freely. Nice! So all I did was switch the existing cover (whose spring was broken off) with the one from the spare carb that was in good order.

 

6-6-19-2.thumb.jpg.16a866ca6d17b94aaa2e91b1bf6f158a.jpg 6-6-19-4.thumb.jpg.6c1063ae9fd79eba6f111b49a0238b99.jpg
Choke cover has spring and a screen. The manual says this must be serviced as a unit so

the fact that the original was in pieces meant it was cooked.

 

6-6-19-1.thumb.jpg.412e775c3b51cb64e3b6c760a7f9eb95.jpg
Spare carb's choke was pretty gunked up, including what

appeared to be very find sand in the bottom. Odd...

 

Bolt it back together and put the carb back on the car. When I fired it, the hissing was still there, suggesting a problem was with the choke body instead, maybe a crack or a casting defect. Pull the carb again and remove the entire choke assembly on the bench. I couldn't find a defect, but I swapped choke bodies just the same after cleaning it out thoroughly with carb cleaner, then reassembled everything. I even made a new gasket between the choke and the carburetor housing since both of those in the carbs were pretty brittle.

 

6-6-19-6.thumb.jpg.262f51a23afb30d27fce318d67df7265.jpg 6-6-19-3.thumb.jpg.2f139eb4d0885e4c6ef143518278fe54.jpg
Disassembled, you can see how the little piston works (red arrow). The bi-metal spring on the cover

rests against the peg on the crank end of the little connecting rod and as it relaxes, the

opening of the choke plate pushes the piston forward, closing the air duct underneath

the right side mounting screw. That was somehow the source of my hissing sound.

 

Reassemble the carb once again, reinstall it on the engine, and fire it up. Hissing is gone! Then I spent some time adjusting the choke, which can be done by moving the cover to adjust the initial tension of the spring. The more tension on the spring, the longer it will take to relax. I wanted it to relax faster, so I reduced the tension by loosening the three screws around the perimeter and moving it in a clockwise direction two "marks." There's an index mark in the center that's probably a good setting for a stock car driven in all kinds of weather, but for this car in summer weather, it didn't need a lot of time on the choke while warming up. The manual says not to go more than two marks, so I guess that's the max.

 

6-6-19-5.thumb.jpg.bacde241ba4e41144f2e0cb0693ff107.jpg
I adjusted the rear carb choke on the bench by moving it clockwise

two marks. Red arrow is the recommended "0" setting
that should be aligned with the blue arrow for average usage.

 

6-6-19-7.thumb.jpg.cfd7c1db789e94a3a0410bfa37984730.jpg
Then I adjusted the front carb's choke while it was on the engine.
I reduced tension by the same two marks.

 

6-6-19-8.thumb.jpg.1ffcb64d6fe6ebe47fc750b56e4dd1cc.jpg
As long as I was at it, I removed the stove pipe I made yesterday
and trimmed it a bit to look more like the original. I'll paint it black
tomorrow so it blends in better.

 

All that done, I fired it up and it ran great! The chokes were still kind of slow to respond but after about 6 or 7 minutes of run time, they were wide open. Hopefully if I'm driving and not just running it at idle it'll warm up much faster. But I was satisfied that the chokes were healthy and operating correctly and it was running pretty darned well. Good progress!

 

The next step was balancing the carbs; that means getting both of them to flow the same amount of air at any given throttle opening. You might think you have them pretty close (I did) but you probably don't. I noticed that if I looked down the throat of the carb, I could see fuel flowing from the jets in the front carb but none flowing in the rear. Putting my hand over the front carb would stall the car but doing it over the rear carb did almost nothing. A-ha! It should be able to run on either carb, no problem, so obviously the rear carb wasn't pulling its weight.

 

I bought a simple little device that the VW guys use to synchronize their carbs called a Uni-Syn--it sits on top of the carb and uses vacuum to lift a little red bead inside a sight glass. On the Buick, I had to turn up the idle quite a bit just for it to register, but that doesn't really matter for the purposes of balancing the carbs. I adjusted the baffle on the Uni-Syn until I got a steady reading about 1/3 of the way up the scale. Then I moved it to the rear carb and adjusted the linkage between the carbs (which adjusted the rear carb's throttle opening) until I got the same reading. I locked down the linkage so they would move synchronously and voila! Both carbs flowing the exact same amount of air. Once they were locked together, I could reduce the idle to the proper level using just the front carb's idle screw and the rear carb would follow. I backed off the rear carb's idle screw far enough that it wouldn't affect anything--it's merely along for the ride now.

 

6-6-19-12.thumb.jpg.cc334158bbe50e1cf1f2919b8ba5cd76.jpg  6-6-19-11.thumb.jpg.4b61a69be180e84b2b068b2a9112000c.jpg
Uni-Syn device allows you to get both carbs inhaling the exact same amount for a given throttle opening.
Easy to use and precise enough for this application. I was surprised by how far off my "tuning" actually was.
Note that the rear carb's idle screw is backed way off.

 

Last step is going to be fine-tuning the mixture. I'll do that with a vacuum gauge tomorrow or Saturday. Sunday is the Buick-Olds-Pontiac show and the Big Guy is definitely going to be there.

 

 

 

I love how methodical you are Matt and now I will have to check my airflow with a synch meter which I didnt do on mine. With idle mixture screws I always use the same approach as I do with the Dellorto carbs on my Ducati's which is screwing them in until the motor starts to stumble and then backing out until rpm picks up and smooths out. Now I will need to get a vacuum gauge like a real tuner! My chokes are set light enough to be fully open in about 2 minutes which is plenty of time for it to settle into a nice smooth idle. Its not an easy motor to stall even when cold. Seven minutes seems like a long time. Cant wait to hear how it feels out on the road!  

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A brief test drive earlier today showed that the engine is running great, so I decided to stop fiddling with it for now. It starts easily, idles nicely, pulls hard without any stumbles, and just goes about its business like it should. I'm not going to tempt fate to try to pull another 2% out of it. It's better than it has ever been, that makes me happy. It does indeed idle more smoothly with two carburetors on it; the engine is a distant, faint rumble but not noticeably shaky. It's a tangible improvement. It still runs at 160 degrees and there's good power everywhere on the tach--again, I'm not going to say it's definitely faster, but it certainly ain't slower!

 

Nevertheless, at least one of the chokes remains open for about the first two minutes of driving. I guess that's OK, but to speed up the action, I didn't want to loosen the springs any more than I already have because it might not close the choke all the way when it's cold. Instead I added some insulation to the stove pipes to hopefully get some heat up there faster. It is a woven material that's supposed to be good to 500 degrees, so it will work fine. It does unravel pretty badly, so to prevent that I used some regular heat shrink tubing on the ends to hold it in place. The heat shrink should be resistant enough to the temperatures it will see under the hood and with the insulation, the stove pipes won't melt it. And if it does melt, well, I'll figure something else out. 

 

6-7-19-4.thumb.jpg.131f5b2aa7d45053a32ded835f3e7a14.jpg
Woven heat insulation on the stove pipes
is held in place with ordinary shrink tubing.

We'll see if it survives...

 

6-7-19-3.thumb.jpg.7d10166de5030b598c6a0b703437516b.jpg 6-7-19-2.thumb.jpg.2b6368db0af94e6b06ca623f2c4b960c.jpg
And installed. I should probably find a plug for the crankcase vent hole in the air cleaner.

 

In preparation for the show on Sunday, I tidied up the engine bay, including painting the radiator and a few other little details. With the intake hose in place and everything wiped down, it looks pretty good under the hood.

 

6-7-19-1.thumb.jpg.30d37091d1d0655ab8478ba63ad6734c.jpg
Clean engine bay looks great and nobody but
an expert will spot the modifications!

 

Once I was done putting fingerprints all over it, I had Michael give it a quick wash--it hasn't been cleaned since we went to the CCCA Grand Classic last August when Melanie filmed that video a few pages back. It was still covered with bugs, which I'll admit I kind of like--it has a sign on it in the showroom that says, "My hobby is collecting bugs." It proves that I drive it. Michael gave it a quick clean up and dressed it up a bit for me. Can you see what he added?

 

6-7-19no2.thumb.jpg.ca6f6760d2cf3b31a7c03578bdbfe277.jpg
Clean and ready to go to the show!

 

6-7-19no1.thumb.jpg.bd5127020527a74d7c91b9198979a7c8.jpg 6-7-19no3.thumb.jpg.50a7e7e989a9ceb95e1e4bd86c3414f3.jpg Front1.thumb.jpg.7a72281f550e0a330c1e13ed788c2b7c.jpg
It always looks great in the driveway! Note that Michael installed the set of bumper ends I had on the shelf,

just to see what they look like. I'm still undecided whether I like them--with the fog lights, maybe it's too much bling.
Compare the first photo here to the very first photo in this thread to see how far it has come.

 

The ride home was effortless. My younger son, Riley, came with me to the gas station, then we ran it down our favorite back road where there's not much traffic. Since the speedometer isn't much more accurate even with the drive gear upgrade, I had him use the GPS to help me get an idea how far off it actually is: 6 MPH slow. So when the dial says 54, I'm going 60. I pushed it up to an indicated 65 MPH (which was 71 MPH!) and it pulled smoothly and didn't seem to mind, so I held it there until we had to slow down for traffic. Then we headed home. We're finally finished after more than a year of working on this exhaust project. The results were definitely worth it!

 

Next projects will be some new weather-stripping, some sound insulation in the doors and floors, getting the gas gauge working, connecting the back-up light, and the installation of the Redi-Rad radio adapter (yes, my radio works!).

Edited by Matt Harwood (see edit history)
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