I have a 1970 El Camino SS 396 and noticed that I had an exhaust leak when it was cold. I pulled the stock exhaust manifolds off and noticed there was a crack on each side on the exhaust port for the front cylinders on driver and pass sides. Mainly close to where the bolt attaches the manifold to the head. The passenger side seemed to have been welded once before. Is this a common problem? These are the original manifolds that were installed at the factory and I would hate to toss them since they are correctly dated for my elky. In the mean time, I ordered a new matched pair from Ground Up, just to keep the elky running and in service for the up and coming ACES show in Maryland. If any one has had similar problems, let me know.

Thanks,

Brian

Exhaust manifolds need to expand and contract with temperature to not crack. If they are over tightened or if the holes at the ends are too small, they will crack. Exhaust manifolds are one of the things that yield in compression and fail in tension,for those of you that are into engineering speak.

See http://www.chevelles.com/forums/showthread.php?t=93261