no4n4me

Hello guys!

Well I finally got my engine after 5 long months of waiting and now I am a bit concerned. I need opinions.

The picture shows one of the pistons at the top of it's stroke. Along the area where the red dots are it just sticks out of the hole. It looks worse in the picture then it really is. At the opposite side of the dots it is just in the hole.

The engine builder said to use a gasket with a compressed thickness of .039.

Does this look and sound right?

Thank you, Marty

zwede

You need t measure how far they stick out. Typically you'd want a quench around 0.040-0.050, so you will need a thicker gasket to get that. But many have gotten away with a tighter quench so if they don't stick out very much you could be OK. Be sure to check valve clearance.

Ben Lurkin

A quick way to measure this (if you don't have a depth mic) is to take a straight edge and place it along the same line as the pin. Using a feeler gauge, measure how much above, or below the piston is relative to the block. They can be out of the hole about 0.010" before you have to worry. If they are, you can buy thicker head gaskets.

Another thing to check is the clearance between the piston and the cylinder wall itsself. If you have your pistons supplier's installation sheet, it will be listed there.

427Hotrod

It's OK. You can measure the high side and then push down on the piston to rock it back down and split the difference. But the measurement in alignment with the wristpin is what you need.

JIM

hugie82

or measure it at the pin centerline. I wouldn't worry too much, you can get head gaskets up to .060 but its up to you to pull the play doe out and check. I'm usually comfortable with .030 clearance on a 6000rpm engine

larrywalk

The looser the piston-to-wall clearance, the greater the piston rock. If the piston is too loose, it might not be ok with a .039" gasket, so you really need to quantify the piston deck height. As for quench, I am very happy with .035".

MotorHead

Piston rock, push down on the high side of the piston and the other side will come up. Best to get an accurate measurement on the piston in the middle above the pin. But I think you will find out the block has be 0 decked and your mechanic is right with .039" gasket. But I do agree with checking how much piston rock (piston to wall clearance) you have, too much is not good and piston to head clearance etc

*I put this on all my posts: Please post back to those who helped you, the final outcome of your initial post

no4n4me

Thank you all very much. I did a much closer check and pushed the high side down, it sure never moved much but your right. It is a 0 deck.

When I checked it at the wristpin it was right there. Gawd I feel good now.

I have AFR heads. Am I correct in choosing a copper ring head gasket?

When I check with the clay method, do I set the head gasket on, or without?

Once again thanks, Marty

Solid LT1

I agree for a steel connecting rod motor I shoot for a minimum of 0.035" piston to combustion chamber clearance.