Inliners International Forums General Discussion Engines GMC SBC valve swap

I think you may be right on the valve seat depth being too deep although I have measured the installed height with the 1.94" valve in the existing unrelieved port and it is still long. To compound things the spring seat pockets in the head are spec'd different with the exhaust being 0.070" deeper in the head without any change in the corresponding installed height. Unfortunate I haven't found a machinist here in S FL who even recognizes a Jummy when he see's one. The last one I showed it to thought it was a MBZ diesel! Needless to say I packed it up and took it back home.