Stock guides were iron (part of the head I know) Most head rebuilders install bronze guides. I’m sure the iron wears better, but the bronze imparts a bit of its own “forgiveness” so to speak if the valve wants to rub against it from time to time. So, iron guides or the “go to” bronze?? My heads have bronze now, and I want to replace with new guides before reassembly. Also is this something that should be done before I start porting them??
Cast iron can be used except if using stainless stems. Bronze are more malleable. Cast iron can fracture. I would go with bronze, as you very unlikely to wear them out before the life of the engine in either heavy duty (race) applications, or just normal driving with the amount of miles most people owning a classic will ever see.
Any stainless steel valve that you should at all consider using in any guide should have a good chrome plating on the stem, then they can go in a cast iron guide which is the way the factory did it.
They’re TA stainless valves, I doubt they have chrome stems. I know Buick used nickel plated exhaust valves, least that what they said in their literature
