So Matt, how hard do these EN16 cranks get when you nitride them? Or do they just finish up nice and black looking?
It is generally accepted that you need `nitriding' steels (eg EN40B, EN41) for this to work.
Also, nitriding is always done AFTER hardening.. not just applied to a soft forging (like a 1275 crank is)
Tufftriding is the recommended process for EN16, but nobody here in Oz does it now, the EPA has canned it, it is a hot arsenic salt bath. Not nice for the workers...

heat treatment ref (1 of many I have read):
http://7faq.com/owbase/ow.asp?SurfaceHardeningOfSteel

read the bits on Nitriding and Tufftriding.

Also see http://steel.keytometals.com/Articles/Art132.htm

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Well that's one down. I'll be looking for another one if my second crank is cactus too (dropped it off to get tested when I picked up my new door stop).

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina