Beemon

Me and my beautiful 1956 Buick

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Just looked at that kit again.. Yeah every photo shows it using a rag joint.. It does show a u joint as included but I could never figure out why it was needed.. Maybe if converting from manual steering??

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2 hours ago, carbking said:

Ben - the WOT from a stop sign was a minor issue from day 1. Remember there were many changes in engine size and carburetor design during this period. The modification of the idle tubes is a work-around, as is advancing the static timing a few degrees.

 

The actual problem is that the 1956 Rochester has no auxiliary air valve. For 1957, Rochester added the auxiliary valve to the secondary.

 

On the 1956 carb, WOT activates the secondary. On the 1957 carb, WOT opens the secondary throttle plates, but the auxiliary air valve prevents air from flowing in the secondary until a pre-determined vacuum is present in the intake. This solved the issue.

 

Opening the throttle maybe only half way for 1/2 a second and then flooring the throttle might also work, maybe worth a try.

 

Jon.

 

This hesitation issue has been widely reported. Since I had so much seat time with the 56 recently I noticed it was an intermittent thing.  Here's some points I noted from my experience:

1: it does not hesitate when the engine is still warming up.  Step on the gas and it just goes smoothly.

2: It does not hesitate if the car is on an angle foreward or reverse.  But it almost always happens when the car is level. 

3: It is intermittent hesitation if turning left from a stop, once warmed up it always hesitates when turning right, unless it's facing down hill.

4: It is intermittent if I accelerate lightly for the first brief second or two. 

5: It never hesitates, or at least I don't feel it,  while moving.

 

Sometimes I am tempted to adjust the choke so it is a little bit applied when the engine is warmed up, but right now it starts easily and we are headed into colder weather.  But now that Jon mentions the secondary air valve, and I noticed no hesitation when the engine is warming up, I wonder if it's possible to adjust the secondaries to open a few millimeters later  and if that would help the situation?

 

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Ben - the 1957 design has an internal auxiliary air valve that is spring-loaded; same general principal as the Q-Jet. One piece of trivia you are not apt to ever see in factory or aftermarket documentation, is that the 4-GC with the auxiliary air valve uses the same spring as the Q-Jet air valve; and the adjustment is 1/2 turn past "touching" at an ambient of 65~70 degrees F.

 

John D - your comments reinforce the idle tube increase work around.

 

When the engine is warming up, the choke is still partially engaged, thus the mixture is slightly richer. If the vehicle is on an incline, the fuel level in the bowl may be slightly higher, thus making the mixture slightly richer. Changing the adjustment of the secondary engagement would make no difference at WOT. The engine needs slightly more fuel to eliminate the hesitation.

 

The idle mixture control screws are greatly misunderstood; THEY DO NOT ADJUST THE MIXTURE! The idle mixture is adjusted internally by the orifices in the idle tubes, the idle air bleeds, and the idle bypass (also air). The mixture screws control the VOLUME of pre-determined mixture. Thus opening up the idle tubes actually DOES richen the mixture.

 

The hesitation when turning right is a different issue, and a factory fix was issued by Rochester. Those who had their vehicles serviced at the dealership had the factory fix applied. When we were still restoring carbs, about 1 out of 3 had the patch, even those that had been "rebuilt". Apparently, the commercial rebuilders did not read the Rochester bulletins. 

 

Jon.

Edited by carbking (see edit history)

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Thanks for the info John, I did not know that. Now i'm more inclined to play with an AFR gauge.  :P

 

It would honestly be interesting to see where the stock carb stacks on an AFR meter. It's not like they had the technology to measure lambda values in a shop in 56. I'm sure since 4 barrels were still new, it was probably looking at plugs and reading vacuum gauges on engine dynos after the what if math was done. 

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I've got three 56 4 barrel intakes lying around. This one had the brass T broken off, so I think I'll drill it out and cap with a pipe plug since the extractor isn't working... Anyways, I wanted to experiment on the shop mill. I think it turned out alright.

 

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The casting for the adapter really sucks, and I found out its pretty porous. Regardless, it's way big on the old pattern side. I don't think I'll bother port matching here, since it doesn't really matter at the carb mouth anyways. At least, in this application, it's pretty negligible with an open plenum.

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I gotta stop doing this to myself. You guys ever seen a slobbering 4GC before? The WCFB is back on... lol. For good... until I get my carb switch mocked up. 

20181005_211456.jpg

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7 hours ago, Beemon said:

You guys ever seen a slobbering 4GC before?

 

Once when I had a float that developed a leak and sank.

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7 minutes ago, JohnD1956 said:

 

Once when I had a float that developed a leak and sank.

This one is leaking from the passage plug and accelerator boot. 

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1 hour ago, Beemon said:

This one is leaking from the passage plug and accelerator boot. 

You will have a real good leak when that plug comes out (and a krispy kritter too).  It didn't do me any good, but if you whine and cry enough maybe Jon will rebuild it for you:D.

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I have two of them, it would be interesting to see how these carbs perform with all the little mods you need to make to have them actually work right. 

 

I'm going to have to pull the aluminum valve covers off, too. They have a lip that goes around the gasket and I think it's not letting the cork seal. It will most likely need to be planed because I don't think there are regular gaskets that don't have the fat edge. 

 

I'm not going to do that on the club mill by any means. When I did the intake, the chuck was out of plane 3 degrees somehow. It's since been zeroed, but I think I'd rather have it done professionally. I'd also need to make a jig and find some aluminum soft jaws. 

 

I can't wait to be done with school and have my own mill.

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Started blowing blue smoke. I know it was inevitable, but looks like I'm blowing out the worn bottom end with my tight top end. Compression readings seem to still be good, and I have seals on the valve guides.

 

Edit: Or black smoke, it's intermittent. Not like my first engine.

Edited by Beemon (see edit history)

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BLGiy.jpg

 

It doesn't cost much to use the 3D printer here, at least if you're certified. I've got some experimenting to do.

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Hopefully the carbs are screwing with the mixture and you're seeing black.. Or maybe a little blue from wash out?? I know you keep having issues with them 

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We'll see. I'm meeting with a local hot rodder soon to use their acid bath for my modified intake manifold. I also finalized my switch for 3D printing... I went through a painstaking process of modeling every component in the system to a degree of accuracy that makes sense to me.

 

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In the shop here on campus, it's about a $10 job since its relatively small and hollow. It shouldn't see any crazy stresses unless the switch bottoms out, which it shouldn't. I also need to refine the mounting arm strength and switch lever length. I'll most likely increase the radius of the fillet and add an additional rib to the mounting arm after an FEA study. The holes in the arm are not final, either. I don't have a modern carburetor on hand, but it should be arriving soon, or so I'm told. The switch lever has a hole on the other side that needs to be tapped for a machine screw and washer to hold it against that side of the housing, while the lever side will have a light spring between the main body and the lever. The dimensions for the switch are pretty close. I purposely made it a little short so I can shim the end if needed. Also, all clearances are within 5 thousandths, just like the original switch. The printers are campus are stupid accurate, and 5 thousandths isn't impossible. I'm excited to see how it turns out! Also, in case you were wondering, this will mount towards the front of the carb. This keeps it from cluttering the coil and makes for easy access. I'm thinking of using a clevis for both the carb and the switch lever.

 

Oh! A family member dredged through the family albums and is uploading them to the internet on a personal cloud. I'm not really a huge fan of that type of thing, but I did find one picture I believe is from before 1958. It's in the bottom right, with my grandparents and their Great Dane.

 

Edit: I'm sure it's going to come up at some point, but yes I am aware of the switch orientation pushing the bull upwards. 

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Edited by Beemon (see edit history)
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On 10/8/2018 at 5:17 PM, Beemon said:

I'd also need to make a jig and find some aluminum soft jaws. 

 

I can't wait to be done with school and have my own mill.

 

For a jig, how about a wood box built to be slightly oversize of the valve covers, filled with bondo.  Grease the valve covers or use plastic wrap on the top side of the valve cover, turn them over with the flange up and sink them into the bondo.

 

Maybe plaster instead of bondo, then just use the box to secure the valve cover for your work.

Edited by kgreen
more stuff (see edit history)

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I'd be hesitant using a wood box on the mill, but I'm sure with enough patience it could be leveled out.

 

BNok9.jpg

 

This is more or less the final iteration of the switch. Looks like its going to work. Right now it fails under 5lbs applied to the nose, so I'm trying to justify beefing up the mounting arm versus the real life application of 5lbs on the body. It kind of sucks because I wanted the switch to face the other way, but that's not how its going to work. I guess I could rotate the switch so it sits vertical almost, like the old Stromberg carbs.

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I assume the nipple on top is for a vacuum hose? Do you plan to keep the original generator for the electrical cutout part of have you reengineered that for an alternator?

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Yeah the top is will be an NPT tapped barb fitting. 

 

The alternator issue is relatively easy, but requires another relay in the circuit to ground the switch and open the circuit without grounding the alternator. The big thing to overcome is the fact that it's the motor mount that needs to be modified. 

 

I am keeping the generator, but if I were to switch to an alternator, I would either find the high mount off of a late 401 or cut the generator bracket off the motor mount.. or ideally go to a powergen, if needed. 

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Okay, I nailed it. Orienting the switch at an 85 degree angle is pretty stout. I applied 10 lbs of force to the outside edge and it has a factor of safety of 1.7. The program is pretty accurate so I believe it. That's good enough for what it will be doing, too. Now I just need to get it printed! 

 

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44519406_10157814678714115_5901419694748

 

Today my grandfather was found deceased in his home. I don't usually share these types of things, but without him I wouldn't be here with a beautiful 1956 Buick Century. He's with my grandmother now, in a better place. I just wish we could have gone to Thanksgiving, where I could have spent more time. 

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So very sorry to hear this sad news Ben.

You have my deepest sympathies.

Doug

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Oh no.  This is a sad turn of events.  You have included him in enough of your posts that I feel like I knew him!  I still recall that picture, that last photo you put up, with him inspecting the paint job!  I imagine he was very proud of all you accomplished putting his Buick back together!  And I imagine he will continue to send you his help in the future!  You may not see those events at the time, but in retrospect things sometimes seem clearer.  Meanwhile, my sincerest condolences on your loss  Ben! 

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