A friend of mine built a 56 235. Had the guides replaced with new cast iron guides and PC seals. Over heated the valves and broke a guide.
I myself do not like replacing the guides. So for 46 years, I have always used bronze liners and PC seals. Not one single failure, and I run my 235 and 261 motors up to the 5500-5800 rpm range. But you have to be careful when using PC seals. They can be very efficient. That is why they entered the market. They were way better at oil control then the o-rings and umbrella seals, and they lasted way longer. There is a feel to the valves when they are just a bit too tight with the PC seals. A good machinist has that feel. If its a speck to tight, you polish the valve stems to get a tiny bit more clearance. You need a little oil, but not a lot of oil.
So frankly, if the guides themselves are not damaged beyond use, I would have them machined for bronze liners. Get some new valves, and a new machinist. Today's Serdi machines do a three angle valve job in one single cut. Get the new valves faced to match the seats, seats cut, and new PC seals with the caveat that the machinist has to check to make sure the seals are not to tight, not too loose but like Goldilocks, just right.
Last edited by Dragsix; 06/01/2023 3:33 PM.
