I got my lme 347 in and running. On cold startups I have over 40 psi oil pressure at idle. But when my car is warm and the idle lowers to 750rpm, oil pressure drops to 20-25 psi. I think it's mostly because of my low idle rpm that it drops so low because when i get moving at over 1000rpm my oil pressure is right back up at 40 psi. My build sheet says .0025" main clearance and .0024" rod. Is everything normal here? Should I think about running thicker oil (german castrol 0w30 synthetic now), raise my idle rpm, or just leave everything the way it is?

 

0W40 0r 5W40

 

your main clearance is a little large. should be .018 to .020. Maybe heavier oil as predator suggested. Too many builders forget the aluminum block expands and they clearance the mains as though it is an iron block.

 

Hmm, LME built my engine, I wouldn't expect that they'd forget something like that. I guess I will try the thicker oil.

 

My clearance is just about the same...38psi idle warm...I use 20W50 Mobil 1...little less with 10W30.

 

I also have had this same issue, although I idle @ 1000 rpms all the time. Anything ever come of this?

 

Nothing's changed since I posted. But at my next oil change I'm gonna try 10w40 or something to see if i makes a difference.

 

Did you ever talk to the guys at LME about this? I never got a build sheet...

 

Whoops, forgot about this thread. Going from 0w30 to 5w50 made no noticeable difference in oil pressure. After talking to a few people, I'm not concerned about this at all. Any time the engine the engine is under load the rpms are high enough to bring the oil pressure to >40.

 

I have a LME block as well, with ported pump. It has the same symptoms 28psi at idle but goes up to 50 at WOT. The crank bearing tolerances have to do with that effect.
Ring seal is super, no oil burning (1qt every 2000 miles). Also ported oil pumps with aftermarket blocks tend to do that as well.