PatriYacht

Anther idea, make sure they aren't overfilled with oil. Possible oil foaming. Does the pressure come back after sitting and cooling? Do the engines have windage trays? Air bubbles get beat into the oil while on plane and then slowly come out at idle. The problem is worse with high oil temps.

CIG3

Well he had the engine builder down there last night. They started the port motor and it idled at 45. Started the starboard and idled at 45. Idled to mouth of river about 3/4 mile and got on plane. With a 1/4 mile the port engine was a 0pressure and the starboard was at 25 at 2800rpm.

As Steve said the thing ran with the big blocks and the same cooler configuration. My thought is something is wrong with the mains (bad line bore) or the oiling system. The motors are coming out this weekend for as autopsy. We'll see what happens.

PatriYacht

Here's one to think about. I bought a Trans Am with a Pontiac 400 in it. It idled badly but oil pressure was normal at cold idle, about 65 lbs. I went for a short drive and it didn't run great, pretty rough. I went ahead an bought it because I wanted the car, WS6, and I figured I could fix it. The price was right. After I got it home I did all the normal tuneup stuff but I couldn't get rid of the miss. Also if I drove it very far and got it real warmed up the oil pressure would drop to about 20 psi. Continuing to dig, I decided to check the cam, see if it had a flat lobe. When I took off the valve covers, I could see a bent pushrod and looking lower I could see there was no lifter in the bore. It was sitting loose in the valley. The engine still had pretty good oil pressure with that big of an internal oil leak! It's a good possibility you'll find something like that if you tear your engines down. And since it's both engines, whatever mistake was made, it was made to both.

stevesxm

not a bad guess... but i don't think so... there is a guy on here named smitty who discovered an oil pressure problem that was related to where the oil groove in the lifter was relative to the gallery... a wonderful piece of deduction and effort... one of those horses not zebras things that really WAS zebras...

but i don't think this is one of those. this is going to be something really basic. the indicator is that it is both motors. thats is simply beyond the realm of statistical probability.

someone has done something wrong and its going to be the same on both motors.

and its may well be something weird... like not putting a plug back in the oil galley after cleaning which would leak like hell internally but w/ cold oil be ok... or a lifter deal like smitty had...

in a lot of years of doing this i can say one thing for certain... when this happened to me, i simply sat down and said to myself..." what is the LAST thing i did that was different from what i have done before...? " and thats where i would start looking. nothing happens for no reason. these motors ran before, they should run now. what specification has changed ?

Budz Motorsports

Well just a shot in the dark but it sounds like the oil plug under the rear main cap.

Budz Motorsports

Well this might make it easier for you. In the back of the block next to the dist. there is a oil fitting take it out and get a hanger or welding rod, measure 8 1/4 in. up and mark a line on it. Drop it in and it should stop at the line flush with the block. If it goes further then the line on the rod then the plug is not set in place!

stevesxm

that is very very good.

bwiencek

I'll vote for the pickup either being bottomed out on the oil pan or it has fallen off... the symptoms are dead on for an oil pickup that's off... when the pan is full the pump can suck the oil up - at speed the level in the pan starts dropping and the pressure drops as the pump sucks air - to do a quick and dirty test - add 1.5-2 more quarts of oil - take it out for a short run - if it holds better pressure - that's it... just DON'T run it a long time with this setup as it may cause oil foaming - of course foamed oil is better than air...