Jump to content

IGNORED

Piston to head clearance?


mbarjbar

Recommended Posts

I just got my short block back from the machine shop. He installed flat top pistons that have valve reliefs. At TDC, the piston top is 0.009" higher than the block deck. Is this acceptable on an early L24. He took 0.005" off of the deck and the head. :paranoid:

Thanks,

Mike:ermm:

Link to comment
Share on other sites

Flat tops with valve reliefs (73 pistons)come out of the block .030 inches. Gasket crush is .060 inches. Dave Rebello told me that they like .060 inch clearance between the piston and head. The way I understand it is that people install them all the time with no problem, but I shaved .020 inches off of my pistons just to be sure. The amount shaved off the head has no effect. The .005 inches off the block is no help. Are you sure you only came out .009 inches? Lay a feeler gauge on the block to measure the distance. Let me know what you come up with.

Link to comment
Share on other sites

How do we know he installed 73 pistons?Did your machinist cut some small reliefs in your pistons?

From what I read, with a stock Nissan gasket( .047 or 1.25mm) he would be around .035 head to piston clearance, which is good for squish.

That is what I am running. I had .005 taken off the deck and stock piston height--no problems.

Link to comment
Share on other sites

Steve......The pistons that were fly cut from the factory......They are 73 pistons......they come out of an uncut block by .030 inches which is OK if you have the open chamber E 88 head. If you are running the early E 88 or E 31 head, you are within .030 inches of contacting the head. Any rod stretch could cause contact (maybe). But many people are running them with no problem. If you are racing and down shifting to 7 or 8 thousand rpm, it could be a problem. Street use....shouldn't be a problem.

Link to comment
Share on other sites

I measured by laying a straight edge on top of the pistion and with a feeler gauge, measured the gap between the bottom of the straight edge and the deck. The 0.009 blade just fits in the gap. It sounds like I won't have any issue with piston to valve or head contact.

The pistons came with the reliefs already cut.

Mike

Edited by mbarjbar
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Who's Online   1 Member, 0 Anonymous, 154 Guests (See full list)

×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.