After a complete engine rebuild I am fighting what I believe is an intake manifold leak. Car starts right up cold with full choke but will not idle when the choke is all the way in. The idle picks up when I spray WD 40 around it which I assume suggests that it is a vacuum leak that I am trying to chase down. The problem is that I have had the manifold on and off twice using a new gasket each time both on the block and the intake manifold and the problem still exists. The carburetor (Carter BB-1) was never an issue before the engine rebuild but I did get back into it to make sure the float level was correct and it was. I even swapped out another intake manifold I had with no change. The gaskets for the exhaust manifold I have been using are a one piece affair that includes the intake manifold gasket and I am wondering if that is the problem. It's been a long time since I took the engine apart for the rebuild and even longer getting it done but I vaguely remember that there was a gasket on each side of the intake manifold and that there were individual glands and rings on the exhaust ports. The rebuilder reassembled everything using a new gasket set he ordered and discarded the old stuff.
Has anyone else dealt with this issue and managed to deal with it successfully? Is my recollection correct and if so can you still get the glands and rings? Car runs great with the choke half way out, go figure!
You know, I had this exact same problem, but I don't remember exactly what caused it. You are correct it is vacuum. I think it had something to do with the acceleration pump on the carburetor. Mine is a RT-08 Carter. Do you have another carburetor to troubleshoot with? I'll look back on my adventures and see if it will jog my memory, but I believe something loose on the carb caused more air to mix with the gas. I keep thinking the acceleration pump was loose and sucking air.
Chet...
Thanks Chet but I am running a Carter BB-1 carburetor and I tried swapping it for one from one of my other cars that ran fine when I first had the problem with no change so I don't think the issue is with the carburetor.
Those gland rings can be a problem. If the new gasket is thinner than the designed one the rings can keep it from being compressed and cause leaks. They don't seal anything they just help line up the manifold & the block. When you have it apart again put it together with no gasket and see how much gap between them and your problem night be easier to spot.
The gasket I am using does not require the glands or rings as it is located by the studs. I assume the engine rebuilder tossed the glands and rings as there were none when I took the manifolds off. I am familiar with the issue you are describing as Model T Ford manifolds use them and at one time a parts supplier was reproducing them incorrectly so they were too proud and the glands could not be compressed. First question, Is my recollection that Plymouth used glands and rings correct and if so is there a source for them? I can make up the rings but not the glands. I can't believe I can't remember if there were any when I took the engine apart and brought it to the rebuilder. But, then again, these days there are times when I can't remember what I had for breakfast!