Valve Stem Seal Question.....

Hello HAMB world!
The engine I have in my Model T is out of 1980 AMC Spirit. I'm in the process of replacing the cam, so a had to get the Felpro head gasket kit and it came with only 4 valve stem seal #70817B (these are the good ones). There are also 8 get by ones. The intake valves are supposed to get the good ones, why not the exhaust vales too? So this is my question...will it harm the value stems to put the seals on the exhaust valve as well?

Thank you!
Jenny

 

If vavle guides are not worn theres no need to have them on the exh. valve. I don't put them. Remember that valve is blow and not sucking. And it's a hotter valve than the intake and its said that it goes a lil tighter when at temp.

 

Jenny,

There are different schools of thought on this.

As Johnny pointed out, exhaust valves do tend to run tighter due to expansion- how much depends a lot on what the engine is doing, the material of the valve, and the material of the guides, as well as the original clearance set by the machinist.

Therefore, a lot of builders will use "good" seals, like the PC seals or Teflon or Viton seals, on the intakes, and plain old "umbrella" seals on the exhausts. This all assumes that the work has been done to fit the good seals, and that the umbrella seals will fit inside the springs.

As Johnny further noted, some people will run intake seals only.

With my builds, which aren't even remotely close to stock as a rule, I use Viton seals on both sides- but in those cases we are using performance guides and valves, made of various semi-exotic materials, and they don't need much oil.

The bottom line is this: if you had the heads properly rebuilt, with good valves, a new valve job, and tight stem clearances, I'd consider using the "lesser" seals on the exhaust. Ask your machinist what he/she thinks.

If the heads weren't touched, and the engine has some miles on it, I'd probably use the better seals on both intake & exhaust...and to directly answer your question, no, it shouldn't harm them. I would, however, check a shop manual to verify that nothing weird seal-or-clearance-wise was specified from AMC- doubtful, but you never know.