J2Davis

First time build. 2002 LQ4, iron block. Very mild cam, stock pistons. Machine shop line bored/honed mains using ARP bolts. I'm now assembling. Used plastigage to measure crank bearing clearances and the figures didn't turn out to what I expected. I measure 4 times. Below is the results. I became more specific with my measurement process and description after the first two tries. I measured each side of the plastigage squashed line on the bearing and the journal.

Attempt 1 Installed side bolts
Bearing Journal
1 .002 .002
2 .002 .002
3 .002 to .003 .002 to .003
4 .0002 .002+/-
5 .003 to .002 .003 t0 .002

Attempt 2 Did not install side bolts

Bearing Journal
1. .002 .0015 to .002
2 .002 to .0019 .0019
3 .002 to .003 .002 to .003
4 .002 .002 to .0019
5 .002 to .0019 .002 to .0019

Attempt 3 Here I measured the front and rear of the plastigage squashed line. Did not install side bolts
Bearing Journal
1 Front .002 rear .0019 front .0019 rear .0019
2 .002 .0019 .002 .0018
3 .003 .0019 .003 .0019
4 .002 .002 .0019 .0019
5 .0019 .002 .0018 .0022

Attempt 4. I turned the crank a little and again measure the front and rear of the squashed plastigage remnants. Did not install side bolts

Bearing Journal
1 Front .002 Rear .002 Front .0019 Rear .002
2 .002 .0019 .0019 .0019
3 .003 .002 .002 .002
4 .002 .002 ???? .002
5 .0019 .002 .002 .002

I know that plastigage is not accurate but it is what I have! My concern is the .003 readings, and the remnants of the plastigate lines were not as uniform as I thought they would be. The surfaces were dry. I thought I would generally have measurements around .0015 especially since I used ARP bolts.

I am thinking of having the machine shop measure the crank shaft bearing clearance to verify acceptable or not tolerances.

Am I worrying too much about this?

Thanks,
Jerry

RB04Av

Short answer:

Yes.

"Measure with micrometer, mark with chalk, cut with axe".

You're in the reciprocal situation. Something like, measure with footsteps, mark with spray paint, cut with laser. The results are equally worthless if not comical. Certainly not "repeatable", which is the very definition of a good measurement.

Send it.

BigBlackCamaro

Stock or ARP bolts aren't going to make much of a difference in bearing clearance.

My question is: Was the crank turned or polished?
If it was I'd stop playing with the plastigage and assemble it.

If it wasn't maybe have someone look at it or just assemble it.

Your readings would be more accurate if you could pull the cap straight off. The moving of removing it is probably making the plastigage inconsistent.

01CamaroSSTx

iTrader: (3)

Plastigauge reading to .0005 ???

.002-.003 is ideal..Being less than that would be more of a concern IMO.