Rockwell Hardness of cam bucket tappets
Rockwell Hardness of cam bucket tappets
(OP)
What should be the Rockwell hardness of shim under cam bucket tappets on an overhead valve engine. I had mine checked and they went from the Rockwell C scale at 40 to 50.





RE: Rockwell Hardness of cam bucket tappets
HRc is pretty heavy load for normal shim material, you may have bad results, usually shims are best tested with one of the superficail tests, or something similar to A-Scale (100kg-Load).
RE: Rockwell Hardness of cam bucket tappets
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RE: Rockwell Hardness of cam bucket tappets
RE: Rockwell Hardness of cam bucket tappets
Close, but the Rockwell A scale uses a 60 kg max. load.
No big deal, just gotta keep on yer toes around here. <g>
"When the eagles are silent, the parrots begin to jabber."
Winston Churchill
RE: Rockwell Hardness of cam bucket tappets
RE: Rockwell Hardness of cam bucket tappets
Finally I found some at $7 each. BUT, through an accident in my shop I bent 4 valves and replaced them. But the shims were wrong. I had read about this so I did it. I just ground about the .005 off the top of the valve. finished.
RE: Rockwell Hardness of cam bucket tappets
RE: Rockwell Hardness of cam bucket tappets
Unless your grinder was very careful, he likely ground through much of the existing case. And by the way, did he grind the contact surface with the proper crown/profile? If your buckets needed to be re-case hardened, it should have been done prior to finish grinding.
Commercial nitride cases are usually quite thin, maybe .015" before grinding, and maybe .010 to .012" after grinding. The reason being, case depth is a function of time in the furnace. And of course, time is money.
You should not use a Rockwell C test setup to check a nitride case. It's too thin. You should use a superficial hardness test scale, like the Rockwell 15-N.
Finally, if you're going to perform a proper heat treatment, you need to know exactly what type of material you're heat treating or case hardening. If, for example, you're performing a nitride process, some metals do not respond what so ever to nitriding. So it's a waste of time. And if you're trying to carburize a part, you will not have any success unless the alloy has sufficient carbon present in it's surface.
If all else fails, get some new ones made: h