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

[John Beasaw III]

Ok dumb question, how much power is there in having the crank machined +.015 on a sbc. Is it actually worth the expense? Is there another purpose for this other than added stroke?

Thanks,
John Beasaw

[Race Wife]

Yes.

[Dean Feiock]

If you are making 1.5 HP per cubic inch, in theory you add 1.5 HP for every cubic inch you add.

A correctly stroked crankshaft will also correct a poorly indexed crankshaft.

[Paul Precht]

Originally Posted by Dean Feiock

If you are making 1.5 HP per cubic inch, in theory you add 1.5 HP for every cubic inch you add.

A correctly stroked crankshaft will also correct a poorly indexed crankshaft.

I personally have found cubic inch to be worth nothing with induction, comp, and cam being the same in a modest bracket race situation.

[Jim Kaekel]

Originally Posted by Dean Feiock

If you are making 1.5 HP per cubic inch, in theory you add 1.5 HP for every cubic inch you add.

A correctly stroked crankshaft will also correct a poorly indexed crankshaft.

Dean is correct, you're effectively killing two birds with a single stone!

[Larry Hill]

Adjusting stroke will not correct index. To fix index try to find a grinder, machine, with new or rebuilt chucks that has index stops at 90*. After its index always check TDC and zero on damper. Rolling the crank to get it to "clean up" @ .020" under while stroking it .014" will some time change the relationship between the two. To check quick index #1 and #6 should arrive at TDC at the same time using two dial indicators.

We use to grind cranks for Kuntz & Craft years ago. In fact we have lost to a 428 heads up with a crank we stoked and indexed for Jim and Keith.

[John Beasaw III]

Thanks for the insight. I knew the rules allowed indexing/stroking, i just wasn't sure if there was a large enough advantage vs expense.

As for my combination i don't have a budget to run with the big dogs. Game plan is .40-.50 under in the heat just to play.

Thanks
John Beasaw

[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.

[MR DERBY CITY]

Originally Posted by John Beasaw III

Ok dumb question, how much power is there in having the crank machined +.015 on a sbc. Is it actually worth the expense? Is there another purpose for this other than added stroke?

Thanks,
John Beasaw

It depends, if you want to run with the BIG DOGS, ...you can’t leave ANYTHING on the table.....