Hardened Cranks

["Bruce Hevner" <scramblr@xxxxxxxxxxx>]

We re-grind our own cranks and I'll have to tell you I have not noticed any
difference in "hardness" of AMC cranks compared to other stock cranks. If
you are referring to "Nitriding" or "TuffTriding" I certainly haven't seen
ANY AMC cranks like that. Not that there AREN'T any (never say never),,, but
I haven't seen them.  Could you please give us specific part numbers of
these "hardened" cranks? What numbers are they when you start and what are
you "hardening" them to?
 We tried sending Chebby cranks out to be Nitrided ( thinking it was better)
back in the 70's. They were straight to start but the process warped them
several thousandth's making them unusable. Maybe the process is better now,
I haven't had one done in years. It's not really a "strength" process any
way. It is a surface hardness process meant to reduce wear.
 I ran into it again in the late 70's when I started doing a lot of Honda
work. All their cranks were Nitrided. But the bearings had worn through the
treatment (it's only a few thousandth's thick at most) and needed to be
reground. We were told they could NOT be reground and reused unless they
were also Nitrided. This is MUCH to expensive a process to use on a stock
rebuild like a Honda so we reground them and used them untreated. It was
several years before we saw one come back for a rebuild with an untreated
crank. Although there WAS more wear to the crank than an untreated one, it
HAD worked. In fact MOST stock cranks are NOT Nitrided and work just fine
that way.
Is Nitriding better? YES it does reduce wear on the crank. I don't believe
it's necessary for the average street engine though. It can't be done
cheaply enough to justify the cost in my opinion. 
But hey,,,, that's just me!!
Bruce Hevner