Leathl_WS6

I spun a beering on no. 7 cyl. It's not bad but I would need to grind it .010 under. I have heard the GM's new Nitrate Hardening on the 502 cranks is actually only between .0003 to .003 thick. Instead of the old method which would make it .030 to .040 thick. Is this true?

If I have it repaired around here there is no one around that does harnening. So I would have to use like that. Not to mention that most likely it is now bent a little and would need to be straightned.

The question is will this shaft be ok fixed or should I just bite the bullet and buy a new GM crank. It will be going in a 502 at the 500hp level.

Thanks ROb

PatriYacht

It's true that nitriding is a thin film that gets taken off when you grind a crank. However, people do it all the time with good results. How much does it cost to grind a crank these days? I've seen new cranks for less than 500.00.

Leathl_WS6

I can have it turned for 125.00. But I would replace with a GM crank. closer to 800.00

blue thunder

Put in a new Scat nodular steel cast crank for $275 and be done with it. You will never break this crank at 500hp. It is rated for 600hp and there is a service factor after that. Anything else is wasting money, other than turning the one you have. That is good too. I have turned many a crank and never had a problem. Nitriding is for surface wear more than anything, not structural strength. The quality of the machine work is way more important that surface hardness.

BT

robyw1

If you just grind one you usually limit the horsepower that it can handle. Mainly higher RPMs 5000 or more. Get a new one.

Roby

ratman

heads up! scott at intense marine has a krytonite billet 4.00 stroke crank, these sell for 3k he'll probably take 700.00 i think he's aking 800 its in the classified section. i was there last week so he still probably has it. thats the hot set up. but if you have a steel crank i'd turn it .010 and run it, Note: bbc cranks bring good money on ebay all day long you can probably get 200.00 for your old one if its a steel crank as it is. if its cast it might bring 150.00... ratman

fountain333

the crank in the 502 was a forged piece and it will be fine if you get it turned .010 it might actually be a little bit stronger because most of the time the small crankgrinders have semi worn out grinding wheels and it puts a larger philit on the journal and i think clevite makes .010 bearings in x and 1s so that is great dont spend the money on a new crank. that crank after it has been turned will still handle 700 hp easy !!

Reed Jensen

Is the journal just "scored"?... or did the crank get melted in that area?... If there is no evidence of "blueing" from excess heat... Just turn it. If it was way overheated and blued, check it for straightness and then grind it. If as you described that it will clean up with just turning .010, you should be ok.

rmbuilder

Rob,
If you do decide to have the crank turned examine closely the work of the shop you hire to do the machining. The journal fillets must have a rounded, smooth radius transitioning the journal to the counter or you run a high risk of a crack developing.
Bob

Infomaniac

Just grind that journal and polish the others. Look at the work carefully as recommended above.

Make sure it is plainly identified.

Give me the casting number. I can get great deals on GM stuff.

Do not buy a cast steel crank.