1941 Buick Exhaust Manifold Temp

[Guest Earl]

I've been reading the discussion on cracked manifold problems for these old Buicks and I've been through that and am beginning to think I have another cracked manifold on my hands. It didn't look that way when I got it out of an ancient junk yard, but these things happen. My Century has the dual carbs on it and I find the rear manifold will get up to around 800 degrees in where everything is kind of tight. Most of the rest of the two manifolds will get around 5-6 hundred. Is this normal? I have both of the heat risers wired to the off position to keep as much heat as possible from the carburetors. I'm almost to the point with this one where I'll have a header made for the rear one if it really has or is cracked. Or go to a single carb manifold they are a lot easier to find. Boy that is a weakness with these things, that's for sure. Mine will go through a set of gaskets on the manifold about every year. I will need to take it off and have it checked again for being warped. I really do like driving the car though so I'll have to work with it and get it sorted out.

[Ben Bruce aka First Born]

Well, Earl, you just shot down one of my assumptions!! That the twin exhaust headers, due to the shorter lengths , did not have the problem of the long ones. I was at the NHRA show here Saturday. There was a '40 coupe with a '52 engine there. . I talked with the owner. He is running an Edmonds duel intake with the '41 duel exhaust manifolds. He said he drives it about 10,000 miles a year. Has done so for several years. NO EXHAUST LEAK.

A fellow forum user has a '37 with a '52, I believe, in it. He uses a high temp silicone with no gaskets. Swears by it. I will try that on mine and let ypu know how it works.

By the way, my '50 Super appears to have never had the manifold of, and by observation, has no gaskets. Does not leak!!

Ben

[Guest Earl]

I really don't understand it with these things. I know that Bob's is reproducing the manifold for the smaller engines and the rear and center sections for the larger engines with the single carb. I just don't think the iron they used years ago was a good as it might have been. I know when I got the '41 Buick I had 30 years ago those old Buick guys all said I was lucky it had the single carb as they did not like the dual carbs at all because of the trouble they had with them. But I thought that it was more of the carbs giving them fits with war time gas than anything to do with the exhaust manifolds. There must be a simple solution to this problem. I do drive my Buick almost every day. That's probably the problem. You do as well, and most don't. So they don't really get into some of these issues. I drove mine 250 miles yesterday down to Des Moines & back and it runs great, it's just this manifold issue. I put a new gasket in it on Friday after work and this time tried a fiber gasket instead of the copper one. I should post a picture of what that copper one looks like! It really shrank up. It makes me wonder if something else is going on in this engine, and the exhaust is running hot because the rear cylinders are being starved for fuel or something. I doesn't seem that way as the engine runs nice. But that dual carb thing is a bit bizarre and they maybe should have done it so both carbs worked alike.

[Mark Shaw]

Are you using the spring (Belleville) washers on the manifold fasteners?

They allow the manifold to expand and contract while maintaining enough clamping force to keep the gaskets from leaking.

They also help to keep the cast iron from cracking.

[Guest Earl]

I will take the manifold off next weekend and try that. I knew that I shouldn't tighten up the bolts so much that the manifold could move some, but it I didn't know anything about changing the washers out until last night when I was reading through the postings after this thing giving me trouble again. The last time I put a copper gasket in there and did put the copper anti seize compound on it and thought that was the reason the gasket worked out of there. So, then I thought maybe the thing is just running hotter than it should. I'm going to order a new set of those washers from Fastenal and they will be here in time next week to give that solution a try. At least it's not something that takes 2 or 3 days to do! Others seem to have solved the problem, so it must just be something that I'm not getting quite right.

[Guest Barneys_Bud]

I would like to know more about the manifolds that are being reproduced for the small engine. I have a spare dual carb setup but it has one that is cracked.

[Guest Barneys_Bud]

Yes they can be a problem. I have a number of these that are cracked and getting them to weld up properly is also a challenge. When I was working on Barney I found that the "Y" pipe had not been welded on correctly and there was quite a restriction at that point. I ran a hole saw down through there and removed the blockage, I only mention that because I believe that restrictions in the exhaust system can aggravate this problem even further. The style of muffler is also important. You do not want a baffle style muffler (if the inlet and outlet do not line up, you have a baffle style muffler) since they have a lot of back pressure. An old muffler that is coming apart inside can also be an issue. It is my opinion that wiring the heat risers closed and having a free flowing exhaust system are very important in keeping the manifold temperatures within reason. Your fuel mixture and ignition can also be a factor.

[Guest]

No one mentioned yet that the rear carb has an extra damper under it with no mechanical linkage to force it open. It's closed until engine RPM's overcome the weight of the round counterweight on the end of the shaft of the damper. If the shaft doesn't get rotated very often becuz your not driving fast enough for engine vacuum to demand it open the shaft can become frozen from corrosion and stick closed. Dual carbs have smaller venturi than singles, so as not to overfuel the engine. Great, until the damper sticks in the rear carb and your driving along at 60 mph with one smaller carb feeding only from the front of the engine. Now your running lean creating intense heat especially at the rear of the engine wich is not gettin enough fuell with the damper under the carb stuck or stick and not opening all the way. Moral, Check you damper under the rear carb and lube the shaft and move it, move it move it the damper counterbalance weight that is. I like the "kiss" principle. Keep it simple senior! Easy to get to and might save your manifold from overheating

Yes they can be a problem. I have a number of these that are cracked and getting them to weld up properly is also a challenge. When I was working on Barney I found that the "Y" pipe had not been welded on correctly and there was quite a restriction at that point. I ran a hole saw down through there and removed the blockage, I only mention that because I believe that restrictions in the exhaust system can aggravate this problem even further. The style of muffler is also important. You do not want a baffle style muffler (if the inlet and outlet do not line up, you have a baffle style muffler) since they have a lot of back pressure. An old muffler that is coming apart inside can also be an issue. It is my opinion that wiring the heat risers closed and having a free flowing exhaust system are very important in keeping the manifold temperatures within reason. Your fuel mixture and ignition can also be a factor.

[FLYER15015]

Were I to run a dual carb set up on my '40 (320cid), and considering the godawfull long distance to the rear cylinders from the front carb, I would surely set it up to run both carbs all the time, and rejet as required. And boy have I been tempted.......

If a little flat head Ford can run 3 Stromberg 94 / 97's, then surely a big honking Buick can stand 2 carbs.

And let the "purists" howl.........

Mike in Colorado