valve stem oil seals

Ed · Post by Ed » Tue Feb 17, 15 1:39 pm

i have 2 types of seal in my gasket kit , which sort goes on which valve?
the guides are the same.
What is the reason behind the 2 types? cheers

Dave-R · Post by **Dave-R** » Tue Feb 17, 15 1:53 pm

One valve stem has pressure on it and the other has vacuum.

Carl · Post by **Carl** » Tue Feb 17, 15 3:39 pm

Both seals are umbrella seals old technology the domed ones or deflector seals usually go on the exhaust whilst the cylindrical seals go on the inlet, but can go on either. To be honest the umbrella/deflector seals are crap as they attach to the valve stem and ride up and down with the valve and just deflect the oil as their name suggests.
Get a good set of positive seals that attach to the valve guide they scrape the valve stem and are held in place by metal retainers or a spring, get Viton if you can they are rated up to 450°

Ed · Post by Ed » Tue Feb 17, 15 10:16 pm

Thanks guys

bratfink · Post by **bratfink** » Wed Feb 18, 15 8:01 pm

Aside question to this:

On other modern engines, with stem seals that work well, I see a machined groove in the top of the step and the stem seal snaps into this to be held in position. Is that worth doing on old engines?