I run small block V8 springs, retainers, and split locks on all the valves. The only place valve stem seals are really necessary is on the intake valve stems, since they're the ones with manifold vacuum against the bottom of the guides. I use positive stem seals, the ones that clamp onto the top of the valve guide, on intakes, and either umbrella type seals, or none at all on exhaust valves. The O rings that fit under the split keepers are an example of manufacturers' "baby chicken" approach to engine building "CHEEP- - -CHEEP- - - -CHEEP!" Use either O rings or positive seals- - - - -not both. It's possible to run too much valve guide sealing, and wear them out quickly from lack of lubrication. The positive seals below can be used on both intake and exhaust if you choose, but the only really necessary ones are the intakes.
www.ebay.com/itm/224857681590?Jerry
