Piston to head clearance

Bob F · Yesterday, 09:31 AM

Steel rod bbc street engine may see 6500rpm if the owner gets too happy some days.
How close have you ran this without tapping the head?
I usually shoot for .040 but this could run a bit closer.
Thank you

Mike Pearson · Yesterday, 01:01 PM

I run my race engine at .036. There would be no noticeable difference at .040. There is a lot of variables to this question. Bearing clearance, rod type, wrist pin stiffness, piston weight, piston to wall clearance. All have an effect on deck clearance.

GTX JOHN · Yesterday, 03:14 PM

In a street engine, I see no reason to
go any closer than 040. I run 050 due to
the fact that I will get carbon build up over
the miles of a street engine that I do not get
on the race cars.

Alan Roehrich · Yesterday, 07:23 PM

Easily runs at 0.042. Might get away with 0.038, but not worth it. You can buy a Cometic to get it exactly right.

Yesterday, 09:31 AM	#1
Bob F Junior Member Join Date: Sep 2007 Location: Bucks Co Pa Posts: 75 Likes: 17 Liked 16 Times in 11 Posts	Piston to head clearance Steel rod bbc street engine may see 6500rpm if the owner gets too happy some days. How close have you ran this without tapping the head? I usually shoot for .040 but this could run a bit closer. Thank you

Yesterday, 01:01 PM	#2
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,473 Likes: 632 Liked 1,987 Times in 599 Posts	Re: Piston to head clearance I run my race engine at .036. There would be no noticeable difference at .040. There is a lot of variables to this question. Bearing clearance, rod type, wrist pin stiffness, piston weight, piston to wall clearance. All have an effect on deck clearance. __________________ Mike Pearson 2485 SS

Yesterday, 03:14 PM	#3
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,742 Likes: 2,835 Liked 2,517 Times in 701 Posts	Re: Piston to head clearance In a street engine, I see no reason to go any closer than 040. I run 050 due to the fact that I will get carbon build up over the miles of a street engine that I do not get on the race cars. __________________ John Irving 741 Stock 741 Super Stock

Yesterday, 07:23 PM	#4
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,137 Likes: 1,617 Liked 1,927 Times in 433 Posts	Re: Piston to head clearance Easily runs at 0.042. Might get away with 0.038, but not worth it. You can buy a Cometic to get it exactly right. __________________ Alan Roehrich 212A G/S