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

John Beasaw III · 02-09-2021, 06:19 PM

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 · 02-09-2021, 06:28 PM

Yes.

Dean Feiock · 02-09-2021, 06:37 PM

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 · 02-09-2021, 07:24 PM

Quote:

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.

MR DERBY CITY · 02-09-2021, 09:01 PM

Quote:

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.....

GUMP · 02-09-2021, 09:34 PM

It's the thing you do when you want that "LAST" little bit......

GTX JOHN · 02-09-2021, 11:06 PM

On a Stock or SS we always run .013 stroked crank.
Has to be indexed anyway at least with all our Mopars
I have seen 10 stockers in class within less than a Tenth
of a second

One year in Class in Denver Natl's = we had a race decided
by .0001

Plenty of Class racing with an hundred or two!

Jim Kaekel · 02-10-2021, 04:25 PM

Quote:

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 · 02-10-2021, 08:18 PM

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 · 02-10-2021, 08:51 PM

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

02-09-2021, 06:28 PM	#2
Race Wife Junior Member Join Date: Mar 2020 Posts: 11 Likes: 27 Liked 13 Times in 2 Posts	Re: Dumb question... +/- .015 on crankshaft Yes.

02-09-2021, 06:37 PM	#3
Dean Feiock Member Join Date: Aug 2002 Location: Pierre, SD Posts: 204 Likes: 0 Liked 49 Times in 15 Posts	Re: Dumb question... +/- .015 on crankshaft 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 Feiock -- Stock 5002

02-09-2021, 11:06 PM	#7
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,736 Likes: 2,808 Liked 2,488 Times in 698 Posts	Re: Dumb question... +/- .015 on crankshaft On a Stock or SS we always run .013 stroked crank. Has to be indexed anyway at least with all our Mopars I have seen 10 stockers in class within less than a Tenth of a second One year in Class in Denver Natl's = we had a race decided by .0001 Plenty of Class racing with an hundred or two! __________________ John Irving 741 Stock 741 Super Stock

02-10-2021, 08:18 PM	#9
Larry Hill Live Reporter Join Date: Oct 2004 Location: Hickory, Ky Posts: 10,658 Likes: 1,949 Liked 10,804 Times in 2,245 Posts	Re: Dumb question... +/- .015 on crankshaft 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. __________________ IHM Used Parts https://ihmusedparts.com 888-821-1817*

02-10-2021, 08:51 PM	#10
John Beasaw III Member Join Date: Jan 2002 Location: Marion, N.Y. Posts: 126 Likes: 0 Liked 2 Times in 2 Posts	Re: Dumb question... +/- .015 on crankshaft 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

02-09-2021, 06:19 PM	#1
John Beasaw III Member Join Date: Jan 2002 Location: Marion, N.Y. Posts: 126 Likes: 0 Liked 2 Times in 2 Posts	Dumb question... +/- .015 on crankshaft 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

02-09-2021, 09:34 PM	#6
GUMP VIP Member Join Date: May 2002 Location: Shelby, NC Posts: 1,823 Likes: 2,174 Liked 2,354 Times in 554 Posts	Re: Dumb question... +/- .015 on crankshaft It's the thing you do when you want that "LAST" little bit......