How much is too much to turn a steel crank?

Have a couple of cranks at the machine shop and one cleaned up at .020/.030 Would this hold up on the strip? Not a cast crank, forged steel sj 327.

 

I'd run it...the rods should let go before the crank causes problems.

 

I wouldn't be afraid to flog a steel crank.At 30 under, it's still way stronger than a cast crank.Just use Good quality rod bolts.

 

Run it Root............
If nothing else,the crank is LIGHTER
Make it REV quicker
It'll be just fine.

 

I'd run it. Some of my circle track friends are running them that way and getting by with no problems.

 

I dunno........030" is a lot of material.

 

THat's on the diameter, it's only .015 on the surface.

 

redline;9,000.don't be a candyass, run it!

 

.030, no problem. I've had racers tell me they've run 8K RPM without trouble with .030 cranks.

 

Biggest problem is the depth of case or how far into the surface the was crank hardened. Generally, the case depth is around .030", under which the material is soft. The surface is hardened for wear and the body is left "soft" for strength - otherwise it would be brittle.

In any event, if the depth of case is .030", you should be OK. Turning the crank journal -.030" is only .015" on a side, still leaving .015" depth of case. If you're concerned, find a heat treating facility and have the check it, which is easy to do.

 

We used to cut the 400 cid crank to fit 350 blocks for the 383 cid engines.

you have to cut the 400 crank quite a bit.

Seems like years ago .040 under cranks were used

 

Shouldn't be a problem. just make sure your clearances are on the money, you've got the proper side clearance, use a GOOD oil pump that will put out a lot of volume, use good rod bolts, and make sure the rods are reconditioned. I've seen the sizes you talk about survive in racing applications that are far more severe than any street engine will ever encounter.

Frank

 

Thanks, that's food for thought.

I may run it on the street instead. I have plans for both.

 

in 2002 I bought a reman CAST crank and it was .040 under.

when I went into my local speed shop to buy bearings for it they laughed at me though..

I had no idea though when I put it on order they were going ot give me something that bastardized... As far as I know the chevy 350 it's in still runs though.