chev manifold

[Phil Waterman]

This issue of cracked manifolds on Chevy straight 6 (stovebolt) is a very common one that seems only to get worse as time goes on. I think that the new gasoline and the asbestos-less exhaust gaskets only exacerbating the problems. New gas burns hotter so that the manifolds are subjected to greater expansion and contraction. The new gaskets are compounded with less or no asbestos so they don’t seem to seal as well or last as long. Another problem seems to be that the manifold gaskets available now are cut to fit all Chevy six cylinders which means they really fit none of them well.

I have found only one solution that really seems to work well and that is a two piece exhaust manifold like the ones made by Fenton. When I first put my C60S on the road with the original 216 exhaust gaskets would only last about a year, part of the problem there is that with radio box the truck is always pulling around 10,000 to 11,000 pounds and has the aerodynamics of a brick, so the engine is always running full bore. Anyway after replacing the gaskets once a year I decided to try the Fenton two piece cast iron exhaust manifold, put the unit on and that was the end of exhaust leaks and it has been in the truck now for more than 15 years. This approach does require a tube Y pipe but that was not much of a problem. The split header seems to be able to take the heat much better, though not a cheep fix at about $350 when you include fabricating the Y pipe it does have the advantage of being a relatively permanent fix. I have not done this fix on my HUP and it is still going through exhaust gaskets about every 18 months, even with replacing the entire manifold with a rare find of a good NOS intake and exhaust manifold. Sorry could not find a good picture of the Fenton Manifold but do a Google Search on “Fenton Exhaust Manifold Chevy” and you will find lots of sources.