You will need a "button", unless the cam is machined for a roller type thrust bearing on the plate to hold it in.
You WILL need a bronze gear for the distributor, unless you enjoy
getting stuck in the middle of BFE with a stripped cam and dist. gear.
Roller cams are made from a much harder metal than a normal cast cam. If
you run a machined cast iron dist. gear on a roller cam, it WILL self
destruct both gears...
The bronze gear is much more forgiving, and
will survive without damaging the cam.
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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"