In case you don’t know Valve stem seals keep oil from dripping down the valve and burning in the engine which creates a blue smoke at startup.


As of right now I am building a 355. The 350 That this head is off had probably less then 100k miles. The bearings show no wear on this block so this is a well maintained and well running engine. The spring that is taken off is the first time it has been taken off and Reveals the valve stem seal (what’s left of it). This was an average seal that was on both heads. I watch a lot of camaros/firebird on youtube and Notice that they all smoke. This may provide some incite as to why.

 

Yup, they always look like that. Using just the O ring seals is a waste of time anyway. If you're doing to do the job, you may as well install positive seals.

 

There are positive seals already in place for many of them. What is the answer to this problem of smoking on start up?

 

move the valve down about a 3/8 and grab the base of the valve and wiggle

no matter what seal you put on them if the guide needs to be knurlled

you know what!!!!!

take them to the machine shop

 

I like the way this man thinks

 

I wouldnt knurl the guides unless the motor is simply going to be a runner.

If any type of performance and a long life is expected from this motor then new guides are a must.

 

Knurling is a bad idea.

 

Use aftermarket replacement seals and it'll be fine. It's not likely the guides are worn, considering that with bad seals they've had too much lubrication.

 

LOL good point^

This is somthing I need to get around to.

 

This is what I was thinking. What aftermarket would you prefer?

 

If you're keeping the valve guide bosses the same diameter as stock, Fel-Pro SS72527. They're listed as intake valve stem seals, but get 2 sets and use them on the exhaust, too.

 

A well-done knurling job has advantages over guide replacement.

 

what are umbrella style valve stem seals? and are they better or worse than OEM?

 

An umbrella seal is a little plastic cup that rides up and down on the valvestem and keeps oil from dripping on the valve guide boss like an umbrella. They're not as good as positive seals that fit tightly on the valveguide boss.

 

I would like to know what they are, please.

 

I just bought new heads like a couple weeks ago, and they have umbrella style, can I swap to the ones you suggested?

 

Knurling work-hardens the guide.

Knurling reduces the surface area the valve stem is rubbing against (roller tip rockers are of benefit here to reduce the side-load on the valve stem).

Knurling improves the oiling of the guides/stems (for the little bit of oil that you want to let down there).

 

You should be able to easily.

 

I never thought of it that way. I was always under the impression that knurling was what you had done when too cheap to do it the right way...but the things you listed there all make sense.

 

I wouldn't want to knurl the guides on a head that's going to see street mileage with stock rockers, but on a racing head it's fine.

 

So, then for a regular, street driven engine, my original impression would be correct? That is, to say that it is done when one is too cheap to do it the right?

 

I don't know that you'd find knurling to be that much less expensive than new valveguides.

 

https://www.thirdgen.org/forums/engi...need-some.html

Last post.

 

everyone that is interested in knurling

go to your machine shop and talk to them

its like asking your mom how to scratch your *****

 

That might have some truth to it.

That also increases the load on the remaining area causing accelerated wear.
Roller rockers are a bandaid solution and an expensive one at that since cheap roller rockers typicaly dont roll under significant load.

High quality valve guids will do all the above better and more reliably. Oiling isnt a problem so saying knurling improves it is bull. Thats just what your corner cutting shop tells you to convince you to pay to much for a job they can do faster and cheaper with a better profit margin.