Dumb question... +/- .015 on crankshaft

[Tom Meyer]

Stock or super stock? A lot of builders are grinding the rods journals to a smaller size say 2.100 down to a honda rod 1.88, less bearing speed and lighter. Tom

[Cotten]

I put that in the category of 20 things that add up to make a difference.

If your goal is 5 to 6 under, at this time, it's not worth the effort or cost.

[Larry Hill]

As my friend George would say “ if it can’t hurt it helps”

[Larry Hill]

Tom stock has an undersized limit on how far under a crank pin or main can be turned. I think it’s.070”, unless it’s a FE Ford crank pin of 2.438” it can go to 2.200”. “If can’t hurt it helps”. That is almost 10% reduction in surface area. And so it goes

[Dean Feiock]

When I built my last engine, I had the crank work done by Bullet. They stroked, indexed, added a large radius in the corners, and treated the crank for around $300 if I remember correctly. I'm not sure if they do this any more or their current cost if they do. I think they will even balance in you have the bobweight.

I do know that my local machine shop charges over $100 to turn a crank. I don't see how having a local shop turn your used piece or buying a ready to go out of the box stock crank is saving that much money.

Add to that, I've used some ready to go cranks by companies like Crankshaft supply in my day job. To pull an already prepared crankshaft out of the box to find it's had the journals welded up and then turned....well it's a sickening feeling.

[Race Clean]

I remember when I was doing my first "Stocker Crank" in 82 or 83 that I had to bring in 3 or 4 Cranks (std size) to the machine shop before we found one they could use to get it both indexed and stroked for me at .010 and .020,I dont remember what max undersize was back then but you didn't wanna go to .030 and dont have another shot at grinding it, if someone already had turned a crank .010 at the rod for some reason it most certainly was waste for a serious Stocker engine,since those days they allowed more and more undersize and also aftermarket parts that was nowhere on anyones horizon.

p.s. I personally think it was a good move for the FE Fords to get the Chevy Rod,they messed up the tracks pretty bad before that

[Larry Hill]

I don't understand how turning a cast crank pin down .238'' to 2.200 would make the engines self destruct less.

[Race Clean]

Originally Posted by Larry Hill

I don't understand how turning a cast crank pin down .238'' to 2.200 would make the engines self destruct less.

No...ofcourse they should have gotten a Rod that fit the engines as they where approved instead of what they submitted..I said it before, it must have been some real Ford lovers in power there at NHRA for a while
But they needed a better rod for sure to able to be in the mix at the time.
I remember talking to Aldon Miller some 20 years ago or more when he was one of the top dogs, he said when they got to 500+ hp they started becoming hard to keep inside the block.

[Rich Biebel]

I worked in an engine/machine shop back in the 1980-1990 era

That's about when the .015" added crank stroke spec came along.

We used a real popular crank shop about an hour away and the guy who did the cranks was very well known and had a ton of experience going all the way to famous shops in California.

We did a ton of work for a real well known shop in NJ.....we also picked up cranks from them and they went to the same crank grinder.
We were just passing them along....

A 454 crank was done for a SS car and it got DQ'ed at Indy for being over the .015" limit after a class win.....

The engine builder never caught it.....he was not happy....the car owner was really not happy.....

I remember the flack after that one......

Stuff happens.....

[Tom Meyer]

Larry what about the guys that put those big old big block cranks in a lathe and take a bunch of weight off? Mostly chevys. Tom