K cam angles

Production K Models

K cam angles

Postby John R » Thu May 06, 2021 7:38 am

On an earlier thread about cam shims I learned that the inlet cam faces are ground at an angle, not just the exhaust cam faces. Looking at inlet cams you'd be hard pressed to say, so decided to measure all four cams of my KHK - believed original, stamped 1 to 4.

Set each in turn in the lathe 3-jaw chuck, other end in a centre. With my best dial gauge (calibrated in half thou steps) checked the end running true. Then cleared the centre away so could use the saddle to mount dial gauge to track across the cam to measure the rise (or drop, whichever way you like to think of it). Then after measuring, finally checked that the end was still running true before measuring the next one.

Results, to nearest half thou measured across width of cam at peak, then at base.
1 (r.ex) .018 at peak, .016 at base
2 (r. inl) .003 at peak, .0025 at base
3 (f. inl) .0025 at peak, .0015 at base
4 (f.exh) .019 at peak, .017 at base

The cams all measured between .43 to .46" width. Using a good old on-line trig calculator (huh, takes me back to school days, sin, cos, tan), the greatest exhaust cam angle is 2.53deg, and the inlet, wait for it, all of 0.3deg - call that an angle?! Well it is (even though I've leaned far more, stone cold sober). Inlet cam angle cannot be manufacturing tolerance on 0deg as H-D's engineering was good. So H-D were so pernickety to design-in a tiny angle when a straight inlet cam face with vertical valve would probably have passed muster.

Something to think about - why slightly less at base? The geometry doesn't change whether on or off-cam. Or does it?
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John R
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Re: K cam angles

Postby panic » Thu May 06, 2021 10:12 am

a straight inlet cam face with vertical valve would probably have passed muster

All WLDR Special, WR, K, KH, & KR intake & exhaust cam lobes are angled because their valve stems, tappet blocks and tappets are.
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Re: K cam angles

Postby hugoct » Fri May 14, 2021 2:15 pm

On KR cylinders from the factory prints the Exhaust guides are installed at 5 degrees 16 minutes from vertical and the Intakes are installed at 0 degrees 35 minutes.
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Re: K cam angles

Postby wz507 » Fri May 14, 2021 3:55 pm

Just out of curiosity what is the date and revision number on the print you are looking at? Thank you.
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