Piston to head clearance

How much piston to head clearance is the minumum? I'm close about the 3 and 9 o'clock area. I have plenty of Valve to piston clearance. BAE block with fatheads
Thanks

 

clearance

how close is close, With or without gasket? That is the normal area of contact I consider rod stretch around .010 I don't know how anyone else does it, but I check it without a gasket. If it pushes the head up, I use washers + feeler gauges to find out clearance. Then figure out rod length, gasket thickness, + compression . It may seen alot, but it is really easy that way for me. But I have different length rods I use for fitting. Since there is a common length you can start with. I order my own pistons + rod length. Hope it helps. Maybe someone else can jump in + help you out. Good luck don.

 

Seams like some where I read you want .150 min. I just did my fathead motor and from about 10:00 to 2:00 I had at least .200 But at 9:00 and 3:00 I had around.125. In a high compression combination it is not uncommon for pistons to hit or "kiss" the heads in those locations. I don't know why but the contours on a piston dome are not the same as the contours in the combustion chamber.

 

Piston to head

I usually shoot for .080" total


Corey

 

min .065 ...

 

I agree with John. I have actually run .060 before, but the pistons shines the head up pretty good. With a fat head, we run between .080 and .100 (with the gasket installed), depending on the compression needed.

 

clearance

compression depends on dome hgt. vale relief , + flat on top. Just remember the flat! Closed up spark plugs on a run + thought I had enough clearance. The learning years. Now I just keep learning alot more things that I thought were there. Don

 

I agree with both John and Ken on this one

What I do to verify clearance is turn the engine over lossen both rod bolts and with a dial gauge on one of the rod bolts just push on the piston until it touches the head .

I also made an adjustable lenght connecting rod out of 2 old rods to get everything right before ordering the rods...

 

Thanks for you input. Had a K-B 10 block (now windowed), new crank, new rods and new pistons. Went about ten feet and broke four rods. All the pistons hit the heads. The motor had .045 clearance with gaskets, apprently not enough.

The BAE block has .045 without gaskets (different pistons) and has .060 gaskets for a total of .105. Should be enough?

Anybody else running around .105 with gaskets?

 

I understand all clearances posted above where WITH GASKETS .

Anyway we run at least .070 with .040 gaskets that way we can put 50,60,70 thick as a tuning aid

So if your compression ratio is fine at .105 run it...