The Excelsior Project, 32: Camshafts

This is the mockup camshaft. The five pieces are held together by the 6mm allen screw on the right. It allows the individual lobes to be "tuned" to the correct opening and closing specs.  The lobes are copied from an early Sportster motor with roller rockers. Nothing super radical.

This is the fixture that allows one lobe to be moved at a time, independently of the other lobe and shaft .

I setup a bicycle chain and sprocket on the mockup head and barrel, and used a degree wheel and dial indicator to check settings.  It was a brain teaser, partly because one cam turned clockwise and the other was anti-clockwise, plus the rocker arms were reversed because of the V-twin configuration. Here I'm using carb slide springs in place of the regular valve springs.

Four camshaft blanks were machined manually from 4130, to be sent out for heat treating and then grinding at Colt Cams.

These are the upper bevel drive housings in their raw state, fresh from Globe Foundry.

In all, five fixtures were needed to fully machine these housings. Notice the counterweight used to keep the lathe spinning freely at about 700 rpm.


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