[BRUCEBLAKE66]

Does anyone know if a set of 093 heads work on a 71 400 motor. Thanks

[Satyr1966]

093 heads were the '66 GTO 389 & high performance '66 421 heads. They will work on a later model 400, I have just recently done this myself. The problems with doing this is that you should have the type of pistons that have valve reliefs cut into them for either the '65 / '66 heads or the later heads. The earlier year heads had a different valve arrangement & if the lift was sufficient, they could come into contact with the top of the pistons if used on a '67 or later block. That being said, 093 heads also have a lot of shortcomings (most of which can be overcome if you are willing to spend the money on them). They have push in rocker studs & require a lot of machining to accept screw in studs. They don't have pushrod guideplates like the later heads do (although these can be added). They don't have hardened exhaust valve seats & this is an expensive addition to have done at the machine shop. They do have a goofy air injection reactor passageway on the exhaust side that hampers flow. They also have small valves. I am a '66 GTO nut & so on my stock car I am running 093 heads. I spent a small fortune on upgrades on them & they are still no better than the stock heads from the '67 to 70 GTOs.

[moegoat]

They will work in two situations, very small close to stock lift cam in the 410 lift range (I would still check piston to valve clearance) or with the generic cast eight valve relief pistons with a higher lift cam, convert to screw in stud or pin the stock ones. I would sell the small valve closed chamber 093 heads & use a 68-70 large valve open chamber 400 head (16, 62, 48, 13, 12 or even the 70 455 #64) with screw in studs if you are trying to raise the compression. Are you trying to use this combo in a 1966 car? Or is it just for anything where numbers are not a concern?