400 Pontiac

I dis***embled the heads on my 400 Pontiac motor in my Hudson and found dual valve springs, one inside the other. Are these hi perf. or the norm for Pontiacs??? I'm wanting to install umbrella seals on the valves and they won't fit inside the springs???

 

Depends on the head casting and year. Some Pontiacs used short dual springs. The "O" ring on the valve stem groove is the seal.

The valve guide usually has to be cut to use aftermkt seals.

 

Motor is out of a 73 Firebird

 

All the Pontiac heads that I have run have stock dual springs and factory umbrella seals .

 

It should just be square cut o-rings, I bought my last set thru Napa.

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=FPGSS5112_0147578895

 

Are they duals or a single with a damper. GM used a lot of valve spring setups that were a single spring with a damper for a lot of years.

 

My 1973 heads have spring and dampener.

 

and we have a winner!!! ive been sittin here for 10 min. trying to remember what that inner thingy is called...a damper...lol

 

Depends on the heads, I have had both styles (dual spring and spring with dampner). What number is cast on the center exhaust port? To put umbrella seals on, the guides need to be cut down, I have done a couple of them with the guide cutter from summit, works pretty well.

 

This is normal from that era. All the Pontiac heads had dual valve springs.


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