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GM tolerance for valve stem tip height

Generation III Internal Engine 1997-2006 LS1 | LS6

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GM tolerance for valve stem tip height

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Nov 16, 2015 | 08:53 AM

#1

thunderstruck507

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GM tolerance for valve stem tip height

Working on a project that requires some precision in regards to valvetrain geometry down to the .001" range. Since my heads are worked including a valvejob on a head that had a couple pretty beat up seats I have a good bit of variance on a few.

Does anyone know how tight GM is on spec for valve tip height across a single head?

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Nov 16, 2015 | 09:02 AM

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I want to say it's +/- .010" or so. With higher lift cams, I don't think it would hurt to be taller.

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Nov 16, 2015 | 09:21 AM

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thunderstruck507

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Quote:

Originally Posted by KCS

I want to say it's +/- .010" or so. With higher lift cams, I don't think it would hurt to be taller.

That is along the lines of what I expected. Most of mine are within a single thousandth but a couple seats needed a deeper cut. I think .007" was the most variance I saw but don't have my notes handy.

Just curious how accurate GM is on uncut heads to determine if these results are going to be easily duplicated.

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Nov 17, 2015 | 07:46 AM

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Keeping all the valve faces the same depth makes a difference in performance for sure. I always cut everything to match the lowest seat.

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