Blocking off the Heat Riser- OK ?

[Guest outlaw car man]

Working on a 33 90-

Anyone have any problems, blocking off the heat riser from the exhaust manifold.

I see where people have done this, just double checking before I get into it. I'd like to block it off, the heat control damper is already removed and welded shut at rebuild.

Thanks,

Sandy

[Guest soldier]

I blocked off the heat riser to my first 1931 Buick series 50 in 1950. Got another one in 2007, and promptly blocked off the heat riser. The only thing you will notice is that you need to let it warm up for a couple of minutes, and then you can run with about 1/4 choke until the temp starts to come up. I hope you enjoy your Buick as much as I do mine. Soldier/Jerry Saunders

[Guest buicker]

Iwas able to find a freeze plug that fit and just left it at that. Seems to be working fine but does take a few few min to idle perfect if it's under 80 degrees outside. I think mine is a similar set up even though it is a 50 series. I didn't mess with the damper on the riser itself I just blocked it at the exhaust. Worse thing I got into was removing the butterfly in the heat riser so I could have it re sleeved. I did think of welding the freeze plug in but it has held so far and it's hard to find someone to weld cast iron confidently. Scares me a bit when they roll their eyes at it. Jay

[Mark Shaw]

Freeze plugs work great for this. Just make sure the butterfly is full open.

I plug both ends of the crossover tube connections and leave the tube in place for appearances.

Edited September 24, 2011 by Mark Shaw (see edit history)

[Guest outlaw car man]

The 33 has two ss tubes going up through the heat riser, two flaps, and a dual set of long openings in a square connection to the exhaust manifold. Putting a round peg in a square hole, with a plug. Not here that I can tell.

I'm going to plug this outfit with something I'll custom make ( I think )

Reason, my riser & intake manifold get hotter then hell in about 2-3 minutes of running. I've used a mirror to inspect in the past, but really can't see the since the heat riser has a reducer in the end.

Got a lot to do, thanks.

[Guest buicker]

I just looked a picture of your 33 it's a completely Different animal than what I had to deal with. Looks like the exhaust is right there dumping heat right at the riser. With no cylindrical tube welding a plate on there may be the only option. Do you have any pics of the opening, just curious what it looks like. I wonder if the riser will still heat up quite a bit due to the close proximity of the exhaust.

[Bob Engle]

If I remember correctly, there is a gasket between the exhaust manifold and the heat riser. Just make a sheet metal gasket without any inner cutouts and instal. You could coat the surfaces in contact with the exhaust with some heat shield to reduce heat transfer.

Bob

[Guest outlaw car man]

Correct. That's what I was planning on doing, haven't figured out a " heat Shield " thing yet, but know I got something around here that will work.

Jay- picture of the 33 heat riser with the square back and inlets, also one installed.

I also have a spare riser, correct one for my 33s, that has real nice riser tubes. ( pictured )

I may swap this one for the one on the G-90.

Pretty chilly in Colorado this morning, when it heats up I'll be attacking the issue-

Thanks,

Sandy

Bob- While I got you, we have gone over this a year or so ago, anything to mess with while the valve cover off ? Last time I checked, everything was running well and squirted Marvel Mystery oil on the rocker arms etc. .004 open, .008 lash.

New engine, about 2 hours on it so far.

If I remember correctly, there is a gasket between the exhaust manifold and the heat riser. Just make a sheet metal gasket without any inner cutouts and instal. You could coat the surfaces in contact with the exhaust with some heat shield to reduce heat transfer.

Bob

[Guest outlaw car man]

Old heat riser had a carbon hole about a 1/4 " round in it.. Couldn't see it till I stuck a long screw driver 1/2 way down. I knew something was bad in the one side due to all the carbon build up.

Pulled the intake off and going to clean & paint and then install the new riser I had.

Made the plug as pictured- Old riser on right of course.

FYI if anyone comes across this with a 33 or ???

Thanks-

[Guest outlaw car man]

IT WORKS- ( green 90 ) Got the new heat riser on with the blocked off part to the exhaust manifold. runs great now without exhaust gases going into the intake manifold. Also there is no heat in the riser or intake as before, I mean it got HOT quick.

Engine sounds very strong, being it's rebuilt and this is some of the first running in 20 years.

It fires up nicely, but is running at high RPMs. I need to study the linkage, think I've got an adjust issue. I messed with the air valve, but really don't need to till I can get the idle WAY down.

Thanks for all the help-

BTW, the black 90 is running tops !

Sandy

[Guest buicker]

That's great I couldn't sleep for two days after I got mine running again, I cursed the marvel for a year but once it came back to life I had to give it an apology. Well I also had to set it back to factory specs but that's ok at least the heat riser is one less thing to contemplate in the future. your car is way to nice to not be out on the road, i am glad it's going again. Jay

[Guest outlaw car man]

Just a thought here to check if you have a heat riser problem: If the intake manifolds get hot, right after a few minutes of warming up, you might have a leak in the riser tubes.

This is what threw me - The intake was to hot to touch as was the riser body, just after a couple minutes of running. Can't be !

Now after blocking off the riser, they run just warm after running for a time.

I also compared this with my other one.

Thanks-

Sandy

That's great I couldn't sleep for two days after I got mine running again, I cursed the marvel for a year but once it came back to life I had to give it an apology. Well I also had to set it back to factory specs but that's ok at least the heat riser is one less thing to contemplate in the future. your car is way to nice to not be out on the road, i am glad it's going again. Jay

[Branded]

Sandy

What did you use for gaskets when blocking off the heat riser from the manifold. Looks like you used shim stock for the block off plate. This is my next step and I'm worried about the gasket thickness and things not lining up.

Thanks for all your help...Dave

[Guest outlaw car man]

That post through me, I thought I'd gone back in time-

I used one heat riser to manifold gasket I had and cut a custom piece from another piece ( high temp fiber material), with no center, and one of of thin sheet metal using the gaskets as a die.

Fit like a glove. Pictures in one of the posts.

Works perfect. Used a redddish high temp exhaust gasket cement also.

Sandy

[Branded]

Thanks Sandy my next step is to pull the heat riser to see whats been done there, or what hasn't been done.

[Guest outlaw car man]

Thanks Sandy my next step is to pull the heat riser to see whats been done there, or what hasn't been done.

Not much to them, the throttle fly as they are called and the two tubes that are usually the trouble makers. Make sure you have two carb to riser steel gaskets, that gives the correct distance for the metering pin.

On the 33s, you sometimes have to train yourself. The best mechanic on my 1933 90, is the one in the mirror. ( scary )

Sandy

[Branded]

Sandy

From what I've read on this sight to inspect the 2 tubes for cracks or holes. What are the issues that have been found with the throttle flys?

Dave

[Guest outlaw car man]

Sandy

From what I've read on this sight to inspect the 2 tubes for cracks or holes. What are the issues that have been found with the throttle flys?

Dave

Can't answer the throttle fly question, know of no real problems that I'm aware of, the main concern is holes, ANY holes , in the tubes.

Is this your car or are you working on it for someone else ? Just curious.

Sandy

[FLYER15015]

Sandy,

You O.K. ?

I thought I remembered a shake shingle roof on your house.

Saw reports of forest fire trash landing in Greeley @ noon.

I have room in the barn for (2) '33's, and there isn"t a tree within 3 miles of my house.

Then you would be ready for our July 1st Buena Vista car show. Spare room's open too.

Mike in Colorado

[Branded]

Is this your car or are you working on it for someone else ? Just curious.

Sandy

Sandy, The throttle fly what is that anyway (I'll do a search) . No the car isn't mine it belongs to a friend. He has had a few other guys look at but it but they haven't solved the overheating issues when running a highway speeds (45 to 50 mph). I told him I would give it a try but I have to admit I'm getting an education. LOL....

Edited June 11, 2012 by Branded (see edit history)

[Guest outlaw car man]

Sandy,

You O.K. ?

I thought I remembered a shake shingle roof on your house.

Saw reports of forest fire trash landing in Greeley @ noon.

I have room in the barn for (2) '33's, and there isn"t a tree within 3 miles of my house.

Then you would be ready for our July 1st Buena Vista car show. Spare room's open too.

Mike in Colorado

It's close, west of me about 15 miles away. TONS of fire aircraft flying over. Smells like a camp fire and ash & soot everywhere. Don't think it can make it here-

Have rounded up a couple old farts that know how to use a 3 speed floor shift in case- Pack them full of guns & beer, and I'm outta here, opp, wife too. HAAA

Here is the big Colorado fire going on from a local- took this last night

[Guest outlaw car man]

Sandy, The throttle fly what is that anyway (I'll do a search) . No the car isn't mine it belongs to a friend. He has had a few other guys look at but it but they haven't solved the overheating issues when running a highway speeds (45 to 50 mph). I told him I would give it a try but I have to admit I'm getting an education. LOL....

You need to take it off- There are two ( flys in 1933) round flaps, as in a regular single bbl carb, that open and shut as the foot feed is engaged.

These are on the heat riser on the bottom, between the Marvel and the heat riser, called officially the Marvel Heat Riser System.

You hit the foot feed, these open as needed, the gas mixture comes up from the Marvel, into the two tubes and "rises" up into the intake manifold, then directed to the system.

The whole heat riser thingy is to pre warm the gas mixture before it hits the intake- It does this by passing heated exhaust gas and engine heat, through the double walled riser.

IF you have a hole of any sort in the tubes in the heat riser, the exhaust gases then mix with the gas/air mixture from the Marvel and you have a mixture of gas/air AND exhaust fumes going to the intake trying to produce power.

Don't work.

It's a common enough problem that Bob's Auto sells the replacement tubes, basically a couple SS tubes, 10 bucks each or something.

Sandy

[Branded]

Are the flys what look like what I would call throttle plates or butterflys?

[Guest outlaw car man]

Are the flys what look like what I would call throttle plates or butterflys?

Yes, I've always called them butterflys ( flys in the Marvel book) . Your PO or someone said they welded the " flappers " shut or something ?

That's why you need to take it off, see what's been done.

Since you are doing this as a favor, I assume, for your buddy, he should spring for a 1933 Shop manual. There will be more to come if you own a 1933 Buick or actually any car in 1932-1933.

OCM

[Branded]

Ok, heres where I'm at. I have a spare heat riser that I'm going to modify if needed. It is on my work bench and I have filled the exhaust side with water. I see no leakage into the air side. So that tells me I have no holes or cracks in the tubes. As far as the flys it looks like I can just remove the flys and leave the shaft. Is that correct ? I havent taken the carb or heat riser off the car yet to get a look at what been done to the flapper. I go back to work tomorrow, I work 7 / 12 hour days then off 7 so wont be much happening on the 33 for a week. I really appriciate the help your giving me on this heat riser modification Sandy.

Yes I will be having him get a manual for this car.

Edited June 12, 2012 by Branded (see edit history)

[Guest outlaw car man]

Never heard of the water trick, guess it will work-

If you remove the butterfly valves, the car will not run. These control the gas/air mixture into the intake manifold and are directly linked to the gas pedal.

You push on the foot feed, it opens the " flys" on the heat riser, and more gas/air comes in, car moves forward.

If it helps, think choke butterfly- pull it -air off, push it- air on. You adjust that manually.

[Branded]

Thats what I thought must have misread your previous post. So all I need to do is block off the heat riser from the exhaust manifold. Correct.......

[Bob Engle]

Don't reemove the butterfly's. Just make sure you aren't leaking vacuum at the shaftends. You need the throttle plate portion to control engine speed, just like the throttle plate in a modern carb.

A while back you talked about adjusting the idle valve. Marvel calls this an air valve. When you open the butterflys in the heat riser, The increased air flow pulls open the spring loaded butterflys in the carburetor. The air valve adjust changes the spring rate to modulate the air flow over the jets. There are tons of discussion about the correct spring in the air valve and how to adjust it. If it is set incorrectly, the engine rolls or stumbles as the air flow is not pickng up a uniform amount of fuel. There is s critical balance between airflow and the correct level of fuel in the carb. This is why there are so many discussions about the float level, and blocked jets ( there are 3, idle, intermediate and high speed) or splits in the jet tubes. As you can see, a loss of vacuum will upset the airflow and fuel feed. leaking tubes or a cracked heat riser casting will allow exhaust gas into the intake side, causing a loss of vacuum.

I hope this helps and does not get you confused.

Bob

By the way, you were correct on the stud at #8 cylinder. You may try double nuts to remove the stud. Many times the stud comes loose at the block when you try to remove the nut.

[Guest outlaw car man]

Thats what I thought must have misread your previous post. So all I need to do is block off the heat riser from the exhaust manifold. Correct.......

Yes, correct, if everything is working OK and no leaks-

Then you move to the 1933 Marvel if you still have problems. ( are you a praying man ?)

BTW, when the car is running, is the intake manifild hot, I mean like can't touch it hot ? Intake NOT exhaust. If it's HOT, can mean a leak in the heat riser tubes.

It will be warm, but not HOT.

I'm guessing if you have a hot intake, changing out heat risers will solve your problem. Don't mess with the Marvel to much or at all till the riser issue is confirmed. The air adjusting screw top should be even with the little thing called the ratchet spring that seems to hold it in place. If you've screwed with it thinking it was an idle adjustment, bring it back there.

OCM

[Branded]

I'm going to run a few more test before pulling the heat riser when I get back to the Buick. Last time I had it running I used a infered temperature gun and the intake was showing about 155 degrees. I'll keep you updated.

[Guest outlaw car man]

I'm going to run a few more test before pulling the heat riser when I get back to the Buick. Last time I had it running I used a infered temperature gun and the intake was showing about 155 degrees. I'll keep you updated.

infered temperature gun. HAAAA what the hell is that ?

I'm to poor for stuff like that, but I'm sure it works great.

OCM

[Branded]

Me too Sandy.It belongs to the owner of the car LOL.....

[Guest outlaw car man]

I just drove my black 90 up and around the area. Then took my wife to get her horses, another couple miles or so.

Got back and let it sit for 1/2 an hour. Took my right infered temperature gun out, AKA my right hand, and spit on my finger and touched the exhaust manifold, it was HOT. Touched the intake manifold and I could tell it was fairly warm, however I could wrap my hand around it for a couple seconds before it got to uncomfortable.

Temp gauge showed 150 ( sitting )

When I had an exhaust leak in the heat riser tubes, I couldn't even begin to think about touching the intake manifold after about 2 minutes of running. It would burn the hell outta ya. When corrected, it was as above- This was in the other 90.

I'm not a " natural mechanic " and have to work at it. I'm a classic , break it to fix it guy, so I ask a lot of questions, have no problem doing that. I do like to learn a lot and become my own personal expert on these minor things.

Ask away, I'll help all I can, but limited.

This forum is loaded with a lot of natural mechanics, free advice and good advice.

OCM

[Branded]

Ok.. this things about to kick my butt LOL... I'm thinking when this engine was put together that the cam and crank gears weren't aligned correctly. Engine revs like it has a govenor on it, just doesn't seem to come up to rpm correctly. Thinking thats why it has a low vac issue. Owner brought me a manual he bought thats on CD. Pictures aren't real clear. Whats the best/easiest way to tell if the crank and timing marks are correctly alignned with out pulling front cover off the engine?

[Bob Engle]

There are 54 teeth on the cam drive gear. 6.6 degrees per tooth on the cam. With theses straight 8's you can remove the #1 plug and see the top of the piston as it approaches top dead center. 32 engines have theintakevave opening 4 1/2 degrees before TDC. this is with the intake valve .004" off their seat with .008" lash on a cold engine. If you reach TDC without the intake beginning to open, you are off on the cam crank timing. One tooth off in the opposite direction would have the valve beginning to lift about 11 degrees before TDC. I hope this helps. I highly recommend that you get a specifications and adjustments manual reprinted reprduced copy. They sell for about $20.

Bob

[Branded]

Bob

What mark should I see on the flywheel and TDC. Is it marked TDC , I have seen a orange or faded red mark on the flywheel.

[Bob Engle]

I'm not sure I can help you on timing. 1931 and 1932 were unique with dual points. Timing on them was set at 7 degrees BTC as marked on the fly wheel. They also had a synchronizer mark on the flywheel for setting the second set of points. One set of points fired odd # cylinders and other set fired even # cylinders. 1933 changed to a single set of points so I am not familiar with their timing setup. Sandy may help here, although he is familiar with the 90 series engines.

Bob

[Branded]

Ok ... heres the latest. I did find a hole in one of the heat riser tubes big enough to put my thumb thru. The heat rise did have a block off plate installed by someone in the past. Thought i had found the problem (not). The fella that owns the car had another heat riser that was in good shape and I installed it. Put everything back together RPMs still didn't want to come up when given full throttle. Owner had another carb that a local fella the restores Model As rebuilt for him. I installed the rebuilt carb engine comes up to speed but will not idle down below about 2000 RPMs (guessing). I think the next step is to have the carb rebuilt by someone that knows these carbs. I read on here there a fella that is the guru at restoring these carbs the came on these Buicks. If anyone knows who he is or how to cantact hime that would be great.

Thanks for all the leads

[dibarlaw]

Sandy:

Just got around blocking off my heat riser on my 1925-25. Am trying everything possible to combat the overheating. I made a plug for the exhaust butterfly port, Bought a sheet of high temp metal composite gasket material from NAPA. $10.00. Made up gaskets for top of riser to intake manifold, which looked to be in bad shape. The exhaust port to heat riser without the hole. Also cut a copper plate to go on the heat riser side. Had some .032 copper around and was real easy to cut. As you can see from the photos the side riser to exhaust manifold gasket was leaking. The carb gasket was paper type instead of the high temp copper. After work today I reinstalled all. Tried to start but "Beuhla" was not cooperating. Found that the electric fuel pump not pumping!(I have to install that vacuum tank)! Replaced another leaking piece of hose to the regulator. Now she has fuel!! Started right up and she seems to be running smoother and will idle down better. The manifold to head nuts needed to be tightened also. After about 10 min of running the intake manifold was barely warm. Before, after less than several min you couldn't touch it. While all that structure was off I decided to scrub down that side of the engine and paint it Buick green. Much better than the Model"A" turquoise that was on it. I will try a drive tomorrow and see what happpens.

[dibarlaw]

After I replaced all of the carb/heat riser assembly and reconnected all the linkages it would not start! Removed the fuel line from the carb and checked the fuel pump. It sounded very noisey. I thought that the 3" length of hose connecting the metal line to the pressure regulator was leaking, replaced it again. When switching on the pump, it was quieter and began pumping. Reconnected to carb and she started right up! Idled much better and ran smoother than it ever had. The intake manifold was comfortable/warm to the touch after 10 min of running. Before, after several min it was too hot to touch! And the radiator did not belch water out of the overflow. The next day my wife and I decided to drive the 1925 to a local farmers market to test on the road. Since I only had a little over 1 gal of gas (2" on the dip stick) I added about 3 more gallons of fresh gas. Seemed to start normally, (of course with the sticking clutch I still have to start in gear) and we were off. For about 30 feet.... Then it starved and quit! Wish I had a photo of Joan my wife pushing the Buick back into the garage while I steered! I pulled the fuel line again, switched the pump on again (very noisey and no fuel). Then It quieted down and began pumping again steadilly. I reconnected to carb and tried to start again. Started and ran for several min then quit again. The 6 Volt pump looks fairly recient, within the last 5 years. I guess I will look for other leaks or blockages. I did drain the tank early in the spring. I still haven't gotten around to installing my rebuilt Vacuum tank.

Another beautiful late summer day not drivig my "Driver".

Larry