Hey, finishing up my bottom end-- does anyone have the specs around for a 3.1's main/ rod bearing clearances? My 2.8 GM shop manual is showing .041mm -.081mm for the mains and .035mm - .095mm for the rods. I plastigaged around .025mm on the rods and mains as my tightest, and .038mm as my loosest...

I've seen specs down to .018mm? Does anyone have a better idea for a 3.1 iron head block? Thanks so much

Andy

For almost any engine rod and main clearances should run between .002 and .0025 " of an inch. A high volume oil pump can help if the clearances exceed the spec.s. Tighter clearances increase the chances of a spun bearing. Looser and the chances are greater of a rod knock. Just the way we used to build engines 30 years ago....

Sounds about like what I've been hearing. I've torqued everything to 46Nm on the Rods and 85Nm on the mains with assembly lube liberally applied, and I can't spin the motor with a half inch drive socket wrench... Is this just because the lube is so much heavier then oil, or is this a problem?