I just put a new high volume oil pump on my SBC from Advance Auto Parts with a new Milodon Stroker 7 quart low profile pan and the proper Milodon pickup tube and my oil pressure changed bigtime from my old oil pump. My old oil pressure was 60-70psi cruising and about 40 at idle or no lower than 30psi and after putting the new oil pump and pan on it was about 40 cruising and dropped below 20psi at idle which scared me! And when I accelerated hard, the oil pressure would drop below 20!!!! So I was told I could have the pickup too close to the pan so I pulled it all off again and ordered a Melling high volume pump to put on and an ARP shaft. I could see in the pan where the bottom of the Milodon pickup was rubbing up against the bottom of the pan so I figured that was my problem because it was too close to the pan. But the thing is with the Milodon pickup, it has a bar that runs underneath the screen 1/4'' from the screen I guess so you can't have the tub too close to the pan. So I thought well maybe that wasn't my problem because of the way they designed it and the guy from Milodon said I only need 1/4'' clearance from pan to pickup. So I put the new pump on anyway and the same pickup but this time tried bending it up a little and put it all back together and now the oil pressure is better. Cold, oil pressure is 70 at idle and cruising but still when warm drops to about 18psi. Now when accelerating hard, the pressure fluctuates but doesn't go below 30.

I was wondering what are the oil pressures of you guys with SBC's out there? Is this normal? Does anybody else's oil pressure fluctuate at full throttle accelerating? And is there such a thing as having the pickup too far from the pan? Would this cause this? Or do I just need to take it off again and bend the pickup up more? How exactly would I check the clearance. I know its suppose to be 3/8''-1/2''. I need some help, I'd really appreciate it a lot. Any ideas would be great. Thanks

Ryan Washington
www.RyansCustoms.com (http://www.RyansCustoms.com)

What weight of oil are you using?

10W-30 Castrol GTX

Ryan,
Nothing wrong with 18 at idle it's just the change that would concern me.
It is most likely that the new pump has too much clearance between the gears & bottom of the pump which will cause lower pressure at idle & lower rpm's.
Also too much bearing clearance, lifter clearance etc. will cause it but if all you did was change the pumps it is more likely it is the pump.
1/4 inch is too close especially with a high volume pump which you don't really need anyway.
You measure it by putting a straight edge across the pan & measuring the depth & then putting it across your pickup & measuring to the pan rails.
It will probably sit crooked so set the straight edge so you get the same reading at both pan rails. Don't forget about your gasket thickness.

10 psi for every grand is sufficient.
thats just my understanding

If I understand your post correctly you just changed the pan and pump. The rest stayed the same. I really doubt that you got that bad a new pump but it could happen. My experience with trick pans has not been very good. Is there a reason you changed from what you had? I would really be tempted to go back to your old combo before you hurt something.

If you want more oil pressure, drop in some 20W50 and it should bring it up 10lbs or so..

Is 20w-50 ok to run? Its not going to hurt anything right? I guess it should be fine, especially in the summer, right? Thanks

Ryan Washington
www.RyansCustoms.com (http://www.RyansCustoms.com)

Actually here's an update, since my oil pan is leaking anyways, I think enough leaked out and the oil pressure doesn't fluctuate anymore. Took the car out tonight, stomped it from a dead stop and a rolling start and wound out to about 5 grand and no fluctuation! I heard people only running 6 quarts in their 7 quart pan. Could this be true? Is my problem fixed? My oil pressure is still 18psi while hot. I'll probably run 20w-50 this summer. Thanks for all the help guys, keep it rollin

Ryan Washington
www.RyansCustoms.com (http://www.RyansCustoms.com)

Same situation here. I had direct lube liftets and my hot oil pressure was BAD!!!! I had no response on the gauge when i reved it up. And i had 30 lbs @ 3,000 RPM. I changed to a HV pump Problem solved...sort of. I still had crappy response on the gauge and it just wasnt right. So i changed to standard solid lifters. Now i have 15-20 lbs @ hot idle and as soon as RPM's hit 1500 i have 40 lbs. Then it goes to around 50 lbs when i smash on it and thats it. So im going to try an M55A pump now with the new lifters and hope for the best. If it dosent work i may be looking at tearing it all down. BUT ive heard with the HV pump, it will cause a cavitation, wich will in turn cause oil pressure to be erratic, wich is exactly what mine does. So lets cross our fingers.

This is odd though, like I said, my oil pressure doesn't fluctuate anymore but when its cold and about 3k RPMs, my oil pressure is really high at 90psi! but when it gets hot, it goes to about 20. Now I'm afraid if I run 20w-50 and when the motor is cold, the oil pressure will be way too high which could be bad for the motor, right? 90psi and 20psi is a big diff, why is this, anyone know?

Thanks again all,

Ryan Washington

my 327 has about five pounds of pressure at hot idle, and 40 at 7800 RPM. This engine sees VERY hard street duty and has never had any problems(knock on wood!).