Crankshafts: Std vs .010 under, etc

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The Artist formerly known as Turbo84
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Clinging to my guns and religion in KCMO.
There's something that's always had me wondering. I've been rounding up parts to build my next engine, and I looked long and hard to find a unused, standard journal size crank. I saw lots of .010 cranks, but I always wondered what the durability/wear resistance those cranks have, given that the thin layer of nitriding, etc, has been ground off. What's the real story here?

thanks.
 
Budget rebuilders use them. There are several types of steel used to make forged cranks and from mild to wild on prices. I broke a crank shaft in my 427 last year and it was the brandX 4340 forging. For what it cost to fix it, I bought the Callies so it would not happen again.
 
The wear rate is what I'm really curious about. I just can't believe Chevy would go to all the trouble and expense to do the surface hardening (which gets ground away when the journals are machined down) if the base crankshaft metal didn't need it to allow a decent mileage life in the engine.
 
anyone know the depth of that surface hardening??? figger it's gotta be much deeper than any 10 mills....

which is 5 mills in depth considering the diameter has two sides....

:eek:
 
The only book (Chevy BB V-8 Interchange Manual) I have that mentions any depth numbers says the range is .003 to .010. Taking .010 off the diameter (.005 on the radius) would remove it all from some cranks, and leave some on other cranks. In other words, it's a crap shoot what you have if you buy or use a machined crank. OTOH, there's no shortage of rebuilt engines running around with cleaned up cranks, and I don't hear any stories about noticably shorter engine life, so it doesn't seem to be an order of magnitude difference in longevity. That's why I'm curious about this metal treatment.
 
Quote from Smokey Yunick, if I could get a hardened crank, I would run it, if it wasn't hardened, I wouldn't pay a dime to have it done. I have run 0.020 cranks in race motors with no problems myself. I have had rod journals turned down to SJ sizes in LJ cranks to get the Ebay Carrillio rods in motors since most Sprint Cup teams have now gone to the 1.88 diamtere journals for their 800HP motors (although they run good dry sump set-ups.)
 
Eric, I'm interested in what you did. Do you know a 3.5 (or 3.48) stroke crank with small (2.000) rod journals?

The honda journal is done to reduce bearing speed, but the downside is reduced journal overlap.

I still have a whole bunch of 2.125 big end, .940 big end width, 6" long, .928 small end carillos.
 
Quote from Smokey Yunick, if I could get a hardened crank, I would run it, if it wasn't hardened, I wouldn't pay a dime to have it done. I have run 0.020 cranks in race motors with no problems myself. I have had rod journals turned down to SJ sizes in LJ cranks to get the Ebay Carrillio rods in motors since most Sprint Cup teams have now gone to the 1.88 diamtere journals for their 800HP motors (although they run good dry sump set-ups.)

Smokey Yunick is a GOD. Remember that.:beer:
 
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