I run a 1000 HP cooler from CP performance that has a built in thermostat. At a normal cruise speed I see 200 in the pan and after a long pass at 6400 RPM the temp gets to 230. I would guess you are getting pretty high oil temps and that is causing the low pressure.

Craig

Don't change your clearances, I just went through that. My 540(600hp) was originally built with tight mains. I didn't build it so i'm not exactly sure what they were but my builder said they were in spec, but on the tight side.
It had great oil pressure, but only lasted one run before Mr. squeaky visited. After that he opened them up to .003 which drastically changed the oil pressure went from 80-90lbs to 50-60lbs.

I have a new sbc with a 7qt pan and and a hv/hp pump and I always see 80psi hot / cold / idle or 4500 rpms, three runs and sounds great....

I am running a 540 at 610 bhp with the Eddie Marine combo cooler as well. I don't know the clearances, but I run about 80-90 psi when oil temp is cold, and it drops to 50-60 when hot (SAE 40 wt). Oil temperature hangs out below 230 on hard runs, and will cool off to below 180 in the pan after maybe 5 minutes of idling in.

i ordered a eddie marine cooler and i am considering 50w mobile one sythetic cuz i now have about 15 hrs on it. is there a good source for 50W? I do not have a thermostat, I took it out yesterday and i was just cringing off of idle....... I ordered a NPT 22 inch cooler so i will have a few bucks in fittings and they said they cannot get it to me for a extra week. Dose NE1 have a link for decent straight 50 W syn oil, anyone?

Mobil-1 20W50 (V-twin) is in fact a straight weight 55 that performs like a 20w50.

Have you checked your oil temps yet?

A high flowing oil filter will give you a few pounds back at idle. A merc, K&N, or racing filter. The valovine sync oil treatment will give you a few lbs also.

I don't know about motorcycle oil. Most motorcycles have a wet clutch. To make the clutch work they have a different additive package than what is recommended for a boat motor. It is like putting airplane oil in a car. After a few thousand miles you cam is gone.

No i haven't checked temps yet. I was going to get a temp package and realized that i definitely need a bigger cooler. So i am patiently awaiting that. Until then i am just taking it easy. but am still nervous at idle. I just hope i can make it through the season and then look at mains and rods next winter. I have a hard time believing in can fry that much oil that quickly???!?!?! Even though it is not the best oil it can't be that bad.... ? What is the oil pathway in a gen 6 block for oiling? what is the last thing in line and that am i going to fry if i run it a little low on oil lbs? In theory every thing is still getting oil... the high volume part is pushing it somewhere....

I have been through a simular situation this year with high oil temps on a fresh rebiuld. I have a carberated 502 with 550 horse. Oil temp was between 260 and 270 at WOT. Installed a 3 x 22 hardin combo cooler and it dropped to 240 with the sender after the cooler. I was using valv 20/50 conventional oil. Switched to M1 15/50. M1 will handle temps past 300. Oil temp now is the same at 240 with pressure staying the same with both oils. 60 lbs at WOT and 20 on a hot idle. Water temp is 150 at WOT and 160 on a hot idle. Lake michigan is 60 degrees.

Was the oil pressure better before your first hard run? You may have heated the oil to much and broke it down. I would change it right away for some straight 40 and take it easy till you get some oil temp gauges in there. Trust me on this one I already wasted a motor this year from high oil temps.