Shelf cams typically have 4 degrees advance built in so no need for timing gears with extra keyways in most cases. Degree it of course to verify where its at. But I’ll go out on a limb here, “most”........ that use an off the shelf cam likely will just stick em in and call it a day and will never need the additional keyways as they’ll never mess with advancing or retarding a cam. Me, with custom grinds (no advance) I’d go with something like this here Rollmaster with keyways in two degree increments. Put it where you want.
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