Re: valve stem seals

Posted by Jack Vines On 2010/3/23 21:56:00

Your engine, your money, your decision.

As for me, I install the positive seals which require machining the valve guide bosses on all my Studebaker and Packard V8s. These type seals are used on most modern engines and were developed because the umbrella seals are old technology which didn't last and don't work very well.

Just so we're all referencing the same parts, umbrella seals are shaped like an umbrella and are a slide fit onto the valve stem and are not a drive fit onto the guide. Those which are driven onto a machined surface on the guide are called positive seals.

I'm also not sure I can agree the Packard V8 valve train is poorly oiled. Many other OHV8s show more rocker, valve stem and guide wear than does the Packard V8. Using today's much better oils, the rebuilt valve train rarely shows any wear after several thousand miles.

thnx, jack vines