Back in the dark ages when leaded gasoline was available, the tetraethyl lead anti-knock additives had the added benefit of leaving deposits on the valve seats that minimized valve and seat wear. As the lead compounds were gradually reduced, and finally eliminated altogether, valve seats began to wear, and the valves slowly sunk themselves into the cylinder head. The fix was to install Stellite valve seats that didn't wear as quickly. That practice these days is about as obsolete as starting engines with a hand crank. It's much more effective (and less expensive) to simply install stainless steel exhaust valves. Fortunately, the same exhaust valves that fit small block Chevy V8s are a drop-in fit for stovebolt sixes. Nothing needs to be done to the intakes, as they're constantly being cooled by the incoming fuel/air mixture, and there's no need to use hard seats, or special alloy valves. I just fitted a set of new valves to a 261 head yesterday, using the commonly available stainless V8 exhausts. Instead of the original O ring seals on the valve stems below the split locks, I use positive stem seals that clamp onto the top of the valve guides on the intakes, and "umbrella" seals on the exhaust valves. DO NOT double up on stem seals- - - -use either the O rings, or the positive seals, not both. Running the valves with too much sealing causes rapid valve guide wear. They need a tiny bit of leakage to stay lubricated.
www.ebay.com/itm/156769335932www.ebay.com/itm/122009255781Don't get robbed on the cost of the guides- - - - -I use these frequently:
www.ebay.com/itm/153212646674?Jerry
