I have built a 1986 chevy 350 with 327 heads circle track oil pan new pick up tube ( oil pump is stock and was in good condition so reused) edelbrock rpm airgap 670 holley. all bearings looked great and clearances were good. Here is the problem. i started the motor last night for the first time. i did the norm double checked everything primed the motor before starting. i proceeded to break in the cam 2000 rpm for 45 min to a hour at first oil press was great bout 40 psi. As time went by it dropped some (to be expected. but after break in lowered the rpm and snapped the throttle a few times. and held rpms at about 2500 for a few seconds. the oil pressure was slow to rise it did not snap with the the rise of oil pressure? any suggestions or ideas???? im totally confused i have never ran into this situation.

 

Oil pump, main and cam bearings. Looks are deceiving. These are the usual culprits for low oil pressure.

 

i was afraid of that i didn't want to pull the engine again. and to fix a error in my origanal post. the oil pressure rises slow with the rise of rpm's it didn't snap up in oil pressure with the snap up in engine rpms like is should. it did increase just slowly.

 

could a clogged or semi clogged oil filter from the breakin cause this to happen? just curious

 

check cam bearing's and main's but if i were you from experience, i would have put high volume oilpump in it, cant hurt spending an extra 50 buck's. if its going to see high rpm's or allot of abuse, i would never put a stock pump in my mud motor. just tear it down throw osme bearing in it and a pump and see whats up,

 

In the old days we used to put some STP in the oil to thicken it to get the pressure up. You can try this to see if it helps, but this is not a permanent solution.

 

1. try an external oil pressure gauge.
2. absolute minimum 1psi for every 100 rpms is sufficient.
3. stock pump could be doo-doo, if you have a rebuilt motor why use a used pump???<--Learned this one 2nd hand. I worked at a Chrysler dealer and the tech on the other side of the building was replacing the motor in a Dodge Charger with the 3.5 V6. He put the new motor in, REUSED THE ORIGINAL OIL PUMP FROM THE BAD MOTOR. 3 minutes later, new motor seized! The pump didnt work. So now a warranty job had to be done again as soon as the next engine came in. $50 and you can get a NEW Melling hi-volume pump.

 

thanks guys, i went and replaced the pump with a high volume pump the pressure did come up. about 65 psi when cold and about 30 after its warm and the idle about 750 rpms. when i turn the old pump by hand it felt stiff. then turned the new high volume pump from orielly's was easier to turn. only thing is i am runnin 15/40 diesel oil in my gas motor ( just cause of it's properties compared to regular car oil. cheaper then racing oil) i figured the oil pressure be higher after it warmed up. but thats ok. 30 pounds at idle i can live with that. atleast till i can build a way better motor

 

ur right racerx i should of replaced it right off the bat when building this motor. i knew better. but i figured i would give it try and save a few bucks. man what was i thinkin...lol

 

same thing the dealer I worked at thought. trying to save $50 cost them $2000.