First off, I want to keep this on topic. Please no comments on anything other than valve stem seals.

I have recently picked up a set of '77 Z-28 882 heads that were 100% factory spec rebuilt (new valves, guides, seats, springs, etc) in that last few thousand miles. They only had umbrellas on all valves. I had them cleaned and magnafluxed, all good. I am going to put positive seals on all the intake valves.

Now comes the questions;

1. Should I install the o-rings on all valves?
2. What to the o-rings REALLY do? What's their functional purpose?
3. Should I install umbrellas on the exhaust valves?

I have no clue about the o-rings, and I'm leaning toward putting umbrellas on the exhaust valves to keep oil out of the exhaust when the engine isn't running, for start up.

Any advise is welcome, just please keep it on topic.

 

Just my opinion:

1. Yes, install the o-rings on all the valves.

2. The o-rings keep oil from traveling down the valve stem. They form a seal between the stem and the retainer.

3. Yes, install the umbrellas on the exhaust valves.

 

my opinion is the same as above-factory '83 heads i cleaned up/checked recently had positive stem seals on the intakes and hard plastic umbrellas on the exhaust.I kinda remember seeing heat resistant reddish silcone rubber positive seals on exhaust of a late-80s era chevy head,but can't remember if they were SBC heads or not...