Valve Guide Seals

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brindo
Posts: 199
Joined: Mon Jun 29, 2009 9:43 am
Location: Western Queensland

Re: Valve Guide Seals

Post by brindo »

Ok so have gone with the umbrella seals and how well they work is yet to be seen but here is what I have found.

From what I read regarding SBCs, if they use umbrella seals they usually run with the small o’ring as well – not sure why though as the o’ring is there to stop oil running down through the collets and down the stem and the umbrella takes care of this also. So if installing higher rate springs without the shields at the top, the umbrella seals will fit, but this is dependent on cam lift and the retainer height.

With a 0.050” raised retainer, there should be around 0.750” between the bottom of the retainer and the top of the guide boss. If you have over 0.500” lift at the valve, you can only run with the umbrella seals and not the small o’ring as well. I think you would need less than 0.480” or maybe even 0.460” cam lift to run with both seal types.
If your running 0.550” lift or more you will go close to squashing the umbrella seal at peak lift. But you would generally have to get the heads machined for a better spring anyway so would also convert to a positive seal at the same time.

For me this was a budget operation and the heads didn’t come off for the cam or spring change. If I was doing this again, I would have ordered a better material umbrella seal. Or found a spring that can still run with the shields.
If anyone is interested, I got my springs from Alex’s Parts and he has been very helpful. http://www.alexsparts.com/
User avatar
REV
Posts: 18
Joined: Wed Mar 08, 2017 9:11 pm
cars: VT V6 L67 Wagon , Corvettes, C10 Truck VT V6 Sedan
Location: Oberon NSW

Re: Valve Guide Seals

Post by REV »

If your guides are in good order there should not be a problem, I rebuild engines and most of the tear downs have the seal cracked or missing and the motor does not use oil or smoke so should be ok. The ford umbrella seal will help just wont sit on the guide boss to well.

Cheers Richards Engine Room
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