The Stovebolt Site Forums The Shop Area Engine Shop Chevy 235 Exhaust/ intake manifold

I have a 235 with the stock manifold that is an exhaust with the intake bolted to it. I have been told that it may be a good idea to not use a gasket and instead bolt these directly to the head, because the exhaust manifold expands faster than the head when it gets hot and a gasket disturbs that process and causes leaks. Also, does anyone here suggest using any type of sealant between the port and the head? I have previously had the intake milled flat and a new gasket, and it stilled developed a leak.

Mike, I'm not sure I understand your question. I've always used the metal type gasket between the exhaust manifold and the intake manifold and I've never had a problem. As for the intake manifold and exhaust manifold bolting to the head, I've never had a problem with leakage using that same style gasket, either...However the late Evan Ritter (Coilover here) showed me how he solved this problem for a straight 8 he owned. He took the high temp RTV gasket sealer (red) and made a ring about 1/8" in diameter about 1/8" from the inside edge of each hole of the gasket (on both sides of the gasket). He hung the gasket and let it sit undisturbed until it skinned over (can't remember but think it may have been 15 minutes). Then he set the gasket in place over the studs, installed the manifolds and tightened each one as the manual said...tighten the exhaust manifold to the intake manifold after both have been torqued to the head correctly. He said he let it skin over so it would compress and seal but not squish out and run all over the place and the manifold had been in use around 12 years when he showed it to me. Hope that helps.

I asked him about the Remflex gasket and he said they had tried them, had unexpected failures and had decided the product didn't live up to the claims.

Jon,

thanks for the advice, I wonder if copper spray gasket sealer would be good to use on these gaskets.

I have recorded exhaust port temperatures on some engines during dyno runs that approach 2K degrees F. during a hard pull. I can't imagine any type of sealer that will survive those kinds of temperatures!
Jerry

I don't know, Mike. Maybe. Honestly I was surprised Evan's RTV stuff worked but he took me out and showed me. As I recall it was a 1937 Buick and I think his problem was more intake manifold leaks than exhaust.

And along that same line, a friend of mine who runs the O'Reilly's in our area showed me some RTV material that had copper in it and the data said it was okay to use on both intake and exhaust manifolds...even if you didn't have a gasket. He did say you need to apply it differently and that it takes 24 hours to cure. So maybe that stuff is a possibility, also.

When you buy a new set of Sanderson headers, they specifically instruct you to use the bead of high temp RTV around each hole, let it sit for a day, then bolt it to the engine. Seems to work, although I wouldn't have believed it either if I hadn't seen it.