Well, I have gone and done it! What everybody fears will happen, happened. I finished my H/C install complete with new intake, throttle body, and new ported TSP oil pump/with double roller timing chain set. And when I cranked it up-----no oil pressure. Then after 10 seconds it finally comes up, but only 20 pounds at idle & 40 to 50 at 3000. I shut it off because I had to run an errand for my wife in HER car. When I got back and started it up again-------again no oil pressure, but only 5 seconds this time. But when the idle got low the oil pressure went to O. It would come back up, but now I knew what I had to do, Dratt, tear it back down and double check the o-ring and pump spacers.

I hope that is all. Don't you think for it to lose the prime like it did, that it almost has to be the o-ring. Either way it has been a frustrsing afternoon!!

That's almost exactly what mine did. I had also reused the stock o-ring being the lazy b*&^%$& that I am. I bought a new one and also put a little rtv on the spacer with the oil hole in it. I don't know if it was in correctly in the first place because it fell out when I took the bolts out. Anyway, I found out that you could put it on upside down and the hole wouldn't line up. Just make sure you use a new o-ring, that it doesn't get pinched and that your spacer with the oil hole is on right side up. At least you don't have to take the valve covers off again and do springs! Good luck.

gettin ready to put a cam in,my oil pump didnt come with an o-ring,is that a separate pc. or was it suppose to come with one?

It's on the pick up tube - not on the pump itself. I'd pick up a new one before you start.

What is the GM part number for the O-ring?

this is what my 395 is doing, but i didnt notice loss of prime when shut off.
20 psi @ idle 30-35 all he way to 6800. i'm pulling the front cover tonight to see if that is the problem.

I want to say the part number is 12771252. Scratch that I was wrong.

The part number is:12557752. You can by a packof 5 from www.gmpartsdirect.com for $3.94, but it would take acouple of days to get them

I ordered two O-rings from Pace, because several Local dealers said they would have to order them also. When I got off work today I went by another dealer and he told me he would have me one in the morning. So I will be tearing the front end down tonight

the shim on the right side has an up and down???? if it's not right is it obvious,i sure hope so!!!!

Yep, that o-ring is a bitch. Took me all of two hours to get the pick-up tubed bolted to the oil pump, made absolutely sure that it was in perfect. Even did it wrong a couple times to know what I would look for if it wasnt seated correctly. Patience is all you need.

when it's wrong how do you know????

Guys it would be nice to have more room, but it just ain't there. I found that using a Pen Magnet to hold the bolt works for me. This is only my second time, but the magnet really does work!

If your still having trouble with that dreaded "O" ring you should pull the pump cover and remove the DRIVE and DRIVEN gears before installation. You install the pump body without the gears. This allows you to wriggle the pump around enough to get the input port pickup tube into the pump without as much trouble and without pinching the "O" ring. Get the pickup tube flange screw started. You then install the shims making sure that the shim on the output port side is oriented properly. Get the pump mounting screws started and replace the pump gears making sure the "DOT" on the gear faces outward and replace the pump cover. Tiighten everything down. This method cuts down that 2 hours installation time that was mentioned quite a bit. The Rollmaster installation instructions don't mention this procedure, but then they're written in a little know language know as Australian and something always seems to get lost in the translation.

A small peice of the o-ring will kinda bulge out from around where the pick-up tube and oil pump come together. It's kinda hard to explain if you haven't seen it first hand. It's hard to see if the o-ring is not seating propery, but a good flashlight will really help. I also used a dentist type mirror to look around the back to make sure it wasn't pinching where i couldn't see.

took everythng apart last night and that was not the problem.

looks like the whole thing is gonna have to come out.

When I took mine apart I didn't notice anything wrong either. Though I am sure that the seal (original) has probably stretched a little, and it had a very slight ridge on one side. There was no sealer on the block side of the oil pump spacer, and I could have sworn that I put some there!?! I don't know if that is it, but I am going to put the new o-ring on tonight and make sure there is some gasket sealer applied to both sides of the spacer.

I think I will try "eallanboggs" method. That should let me get some rtv on the pump and spacer without smearing it everywhere.

ttt ttt

Had this problem doing the install the first time and was having trouble with the spacers and when we fired it up only 20 psi and @ 45 at cruising speeds. Took off the front cover to dicover the spacer was on upsidedown and it blocks about 1/3 or so of the hole after getting it right it was fine. other than that its the O ring.

When I got the new O-ring from dealer and compared the two, it was like night and day. The new one was 1/3 bigger than the old one and that explains why the pump wasn't pulling oil. It was sucking air, because the original O-ring had shrunken!
Put in new o-ring and some flange sealer on the pump spacers. Cranked it up and the oil pressure immediately went to 60 lbs.

Motto of this story. Never use a used O-ring!