Crank being turned 10/10---do I need to get it nitrided

[Chatt69chgr]

I was reading Larry Shepards new book on rebuilding and upgrading 340 and 440 6-pack engines.  He says that if you turn the crank that you need to have the journal surfaces nitrided.  Does anyone know if Mopar cranks were nitrided from the factory?  My understanding from a little surfing of the net is that when you nitride the crank (several methods can be used) you are, in effect, case hardening the surface increasing the surface hardness from around 30-35 rockwell to around 55-60 rockwell.  The hardened layer is pretty thin.  I can see why this would be desirable for a real high horsepower build or for racing.  I am more or less just building a little hotter than stock engine that will not turn over 6000 rpm.  My crank needs to be turned 10 thousands on both the rod and main surfaces to clean up.    By the way, I have no idea whether this service is available in my area or what it costs.  One article I read on the net said $200.
I just wondered what is commonly done as far as this is concerned.

I've done some more surfing on the net today.  Found out that most stock cranks are induction hardened which yields a hardened thickness of 60 to 80 thousands.  Also found articles that say that nitrided hardness layer is from 10 thou to 30 thou thick typically.  The following articles are interesting:
http://www.carcraft.com/techarticles/116_0308_crankshafts_how_to/index2.html
http://chevytrucks.org/tech/cranks.htm
http://www.crankshaftco.com/steel-crankshaft-hardening.html

Does anyone know what Chrysler did in the late 60's and early 70's as far as hardening the journals on their cranks.  If they induction hardened, then turning a crank 10, 20, or even 30 thousands would not cut through the hardened surface and render this whole issue moot in my case.  I'am betting this is the case since nobody seems to be talking about this very much.

[Challenger340]

IMO,
Negative on the Nitriding for what you're doing, not required.

I've havd it done before on sereverely modified stock Forged Cranks, in equally severe Race applications, but for what you're doing, it's a waste of time and money.
Just grind it .010/.010 and don't worry about it.

[firefighter3931]

IMO,
Negative on the Nitriding for what you're doing, not required.

I've havd it done before on sereverely modified stock Forged Cranks, in equally severe Race applications, but for what you're doing, it's a waste of time and money.
Just grind it .010/.010 and don't worry about it.

I have to agree with Bob here.....on a mild build nitriding is unnecessary. Think of all the old 440 cranks that are offset ground for lowdeck strokers that are running around on the streets and some at the track. Guaranteed that you're waaaay past the factory nitride treatment with a 2.20 rod journal. 


Ron