Aaron,

Having read your post on the XR head porting thread. Can't you just notch the cam lobes as you suggest in your cam installation article on the NRHS tech section?

I would think that would be a better solution as you suggest in your article rather than trying to modify the pinion race. Or, is there something different about the early iron cases?

I am also sure you have to grind the bottom of the lifter bores as well as shown in your article. I am installing the Andrews XR-1000-1 cams (.560 lift)in the bike and want to make sure all goes ok.

Great article on installing the cams by the way.



Thanks,

Jesse, ironheads just don't have much room there at all. You have to do both, heavily clearance the race and chamfer the back of the lobe.

I installed a set of those Andrews 560's once and I seem to remember that they were small base circle. So they didn't need nearly as much clearancing work. Later I swapped'em out for Red Shift 570XR's and I had to do a whole bunch more clearancing. So you might be alright.

HOWEVER ... the Andrews grind, if I remember right, had a ton of TDC lift, and to get them to fit I had to sink the bejeezus out of the valves to have any valve to valve clearance at all. That's one of the reasons I went to the Red Shifts. I made more power with the Red Shifts, despite not having all the specs I wanted, because I didn't have to molest the heads so bad to get them in. YMMV.