Story is i bought the engine used with low miles. I pulled the pan to check the bearings before putting it in. I found the mains and rods had more wear then i would to have liked to see for a engine with less then 10,000 miles. The pickup was bent way up and not aliened properly. So i purchased a new melling select 10445 oil pump and pick up get the pickup set to specs, new clevite main and rod bearings and new arp rod bolts. All torqued to spec using the moly lube ect. Got the pickup welded and put it in the car. The engine runs fine has 70-80psi cold idle. After warming it up it has around 40psi hot and 70psi at the touch of the gas. Now making a wot pull 1-4th oil pressure will go to 70-80psi quickly drop to 40psi around 5000 rpm's then climb back up to 70psi by 5300-5400 and hold to the gear change. It will do this in every gear except fourth where it does not drop at all. So i verified it with a mechanical gauge same thing my stock gauge is dead on. The windage tray is in place and in the right direction and torqued to 25 ft/lb's. That was the first thing that came up in a search. Then i contacted a local engine shop and they said it sounds like the relief in the pump is getting caught up so i ordered a pump through them brought them my pan and had them set the pickup clearance and weld it. While i had it off i pulled a main to check one the bearings (looked new) and two that little ball thats supposed t be in there. I also went ahead and put a new filter adapter in from Gm. I get it all back together and it does the same damn thing. Any ideas? Everyone i talk to is astonished. Another thing to add is it does leak a couple drops of oil thats by the rear of the motor when i park it over night but im pretty sure its coming from the intake gasket. Any help at all. I had some pretty big plans for this engine but with a oil pressure issue im not about to dump money into if its going to take out my high dollar parts (ex heads cam)

Any ideas?

Engine has
Stock crank chamfered
Eagle forged I beam rods
Trw pistons
Clevite H series rod and mains stock sized
Bearing clearances are 3-4 thousandths

 

well what are they?

is that a high volume pump? it sounds odd, I'm interested in what you find

 

Some mains are 3 some were 4 I forgot if the rods had a variation. Neither pump was a hv.

 

what ones? the front 4 should not be more than 3 imo...

thrust does not matter too much, mine has 5 and seen 8500 a few times and has alot of runs on it

 

That was it the front four were 3 and the last one the one the oil pump bolts to was 4. I did not check thrust or rod side bearing clearance as it was supposed to be all good. But we all know how that goes.

 

.003" - .004" are mighty big bearing clearances. What equipment did you use to get these measurements?

 

plastic gauge.

 

Javier, i think is the guys name had an old thread that just got bumped. He ended up taking 2.5 quarts out of his pan and it solved his problems. It is a long thread with some great information.

 

Im the one that bumped the thread. He was running a 7.5 quart pan i am running a stock pan.

 

thats not accurate at all FYI.

 

Since it doesn't do it in 4th gear, to me it sounds like there's not enough oil in it? Add some and see what happens.

 

It was all i can afford at the time I didn't want go go out and buy mics. I do realize its not the best ways but it better then not checking at all. They should have all been fine anyways as the only reason i replaced the bearings in the first place was because the pickup was not installed correctly from the previous owner causing oil starvation. Now say the bearing clearances are off wouldn't that cause a oil pressure issue all the time and not just under load sometimes but not in fourth gear? It has great pressure at idle and anywhere in part throttle. Someone on another site suggested that it could be the oil drive gear at the top, but i think i would have saw teeth in my pan on one of the three times i pulled it off. Regardless i will check it anyways.

 

just pulled the intake off, and checked the drive. Its got all its teeth on it so thats fine. on to the next.

 

Try a primer

I was just statin g that plasti gauge is not accurate, did you do anything to the bearing? if not then I would say its probly closer to .0025 from what I ahve seen on bearing out of the box

 

What is a primer? I did not touch the bearings i put them on with assembly lube right out of the box. I appreciate the help guys