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By dennis22 - 5 Years Ago
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Hi Guys,
I want to replace the umbrella valves seals with positive seals and trim the valve guide down for future possibility of a higher lift cam. Just wondering if anyone knows a source to buy valve guide cutter, what size is required and also what positive seals I can use?
(It more hassle than its worth at the local machine shop- if you know what I mean)
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By Ted - 5 Years Ago
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While I prefer to machine the existing guides for a 0.562” positive type seal, not all Y heads will machine cleanly at their tops for that particular size as the original guide hole itself may be off center with the external dimension of the guide. In those cases, the guides are machined for a 0.530” seal and in a worst case scenario, a 0.500” seal. I prefer not to use the 0.500” seals unless absolutely necessary as it does minimize the amount of material at the top of the guide in which to hold the seal. Guide breakage at the tops of those iron guides can also happen when machining for the smaller seals. Where triple springs are being used, then the 0.500” seals are sometimes the only option.
For a one time use, the investment in tooling to accomplish this is going to be steep. Goodson comes to mind for most of the tooling while U.S. Seal Inc. is a good source for the seals themselves. Some of the camshaft companies also offer the various cutters in their catalogues. From a cost standpoint, any competent machine shop should be able to accomplish what you need at a fraction of the cost compared to what it will take to get both the appropriate tools and seals in your hands. But if simply wanting the satisfaction of doing this yourself, then the cost is just another consideration and not the major factor. Regardless of who is doing this, insure that the retainer to seal clearance is adequate for the valve lift you plan on running.
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By dennis22 - 5 Years Ago
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Thanks Ted!
It’s part satisfaction of doing them myself and part avoiding the hassle of waiting for the machine shop to get them done. I know if I spend the money I can do it myself in my own time and learn a thing or two along the way.
I’ll try the Manley .530 from summit. I have a few sets of heads that I might use at some point, so that’s enough justification.
Thanks again for the thorough explanation!
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