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TerroRx7 05-04-2006 02:54 AM

SBC heads with weird valve seals
hello all

I bought a 1986 GMC K15 which has a mexican reproduction 350 which was rebuild recently

after inspecting the heads I found no valve seals and they won't accept regular 350 valve seals

I've tried many types and I found a set of stock 454 Umbrella style seals that fits perfictly

but after mounting the springs I found that they touch the seals even when uncompressed

what should I do ?
Replace the springs with something bigger ( wider ) ? stock? aftermarket?
try other seals ?


302 Z28 05-04-2006 05:47 AM

Regular 350 SBC valve seals are just "O" rings. The umbrella type seal you show usually requies the valve stem boss to be machined.


TerroRx7 05-04-2006 03:39 PM

most 350s I have seen have both O-rings + umbrellas

this engine only have the O-rings but it is burning some oil

so is it enough to use the O-rings only ?

302 Z28 05-04-2006 03:56 PM


Originally Posted by TerroRx7

so is it enough to use the O-rings only ?

GM has been doing it for 50+ years.


GoneNova/406 05-04-2006 06:13 PM

positive stop viton seals is what most engine builders recommend,
summit has them and shows a picture of them.

RPM 05-04-2006 07:40 PM

The stock o rings will work fine if the stock oil sheild is there. You have to compress the spring then install the o'ring then the locks. If you put the o'rings on first they won't work.

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