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Perfect Circle 9010 valve seals


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In the Shade tree mechanic rebuild articles posted in the "M10 rebuild project" thread the section on heads mentions these Perfect Circle valve guide seals, #9010 (or VS-17-18 I found online as a cross reference). I have a head that was modified to use these seals many years ago - but they're leaking. The car ony has 39k miles on it, (I bought it from the original owner, reasonably confident of that mileage) which makes me wonder just how good of a solution those seals were. Of course it'd be easiest to just swap in new seals, but: #1 I can't find them, & #2, as mentioned, I have my doubts about how good they are. 

It's a 67 121ti head that's been modified to work with some 10.5:1 pistons and there are good reasons to do this right - is swapping in the newer style valve seals the way to go? 




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I’d probably consider swapping in new style seals, even if it meant I was replacing the valve guides.


While I agree that 39K miles is not a lot of mileage — and I certainly don’t dispute that number — those seals are 50+ years old and probably saw their share of “sporty” driving from Day One! 😳


Best regards,





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I remember those seals, were they not the teflon seals, white in color?    If so, I tried them on a couple of engines,   didn't like them, seemed way too hard, even when new and I think that I ended up replacing them fairly quickly.   Remember, if you do replace the guides, you will have to a touch up grind on the valves and seats as they won't match any more     I like the new guides with the new smaller seals much better


Thanks, Rick

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18 minutes ago, Son of Marty said:

You can cut your existing valve guides in place with a valve guide cutter like this.

PC Valve Guide Cutter, .494

That jibes with what the original owner told me about the process of adapting the original guides. Evidently the local NAPA auto parts would loan you that tool to cut the guides. I know that in some cases originality is important for preserving a car, my current plan is to follow Steve's advice and replace the guides with the newer design. 

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