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[Steve]

Here is what I wrote: "964 and 20/21 cams can be used without piston-to-valve contact, however anything with more lift/duration requires careful measurement and piston modification to work. We have used Mod S cams with these pistons, but we had to machine them to fit."

Note that I mentioned the need to machine them to fit.

I have used Mod-S cams with the wedge-dome pistons several times, however one needs to machine the intake side a little bit for valve clearance. The drop in CR is small and its well worth the effort.

Certainly, this requires the engine builder to measure piston-to-valve clearance and have access to a lathe, but none of these procedures are difficult to have done. I assume you have the ability (or have some assistance) to make those measurements and I'd assume you have a local machine shop that can machine the intake side of the pistons for additional clearance.

[Litle brother]

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[Litle brother]

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[Steve]