Modified Cam Followers

[Alan]

I always meant to do a proper analysis of what happens, but essentially the flattened tappet causes the valve to open and close more rapidly and possible earlier and later, too. The acceleration forces are high and, yes, there will be an increase in noise and in wear rates. Mostly, with standard cams I use tappet blocks ground with a 2inch radius - it’s easy to produce that on a lathe but H&S might disagree.