ok heres the deal, i just put a 350 me and my dad built in my car,weve built 100+ 350s, it has about 5psi of oil pressure in gear at 500 rpm, hot, when cold 60 psi, when you rev it 60 psi. and when your going down the road and you punch it the oil presure drops to about 20 when you let back off the gass it flys up to about 60 then drops. the crank was just done, new rod and main bearings, and it has a mechanicle gauge. and when its hot it has a electronic miss from idle - 1100 rpm and when you first punch it about 3000-450. i was thinking that was the distributor, i didnt have it hot tanked after the water in the oil thing, could it be a cam Bearing? or an oil passage, maybe something with the distributer(where it meets the oil pump) please help, thanks

 

I would replace the sending unit to the oil pressure guage and be sure the actual guage is accurate before doing anything drastic. If they both check out be sure that the pickup is still in the oil pump and that the distributor is fully enguaging the pump.

 

tomarrow ill probabl try and put my dads vette distribor in it, if that doesnt work, i dont know what to do to it

 

that would happen if the oil pump was sucking dry for a few seconds... are you sure there's enough oil in the pan and that the pickup wasn't mounted too high?.

 

well i have 5- 6 quarts in it, and thats the second pump, and thats how we usually do it so.. thats last resort, I would have to pick up the motor to drop the panoh and at 700 rpm in park its about 10 psi hot, very low, so i dont think its all the pump, it might be some of the problem however

 

Would these symptons becaused by to much clearance between the crank and the bearings?

 

Oil plug(s) in the front of the block behind the cam gear missing or a bad or mis-installed cam bearing, and oil pump pickup fell off...

 

cam bearings were my next thought, not the plugs however it had 80 psi 2 years ago when we took it out, we recently had the crank turned and new bearings for it. it could be the cam bearings, it sat in a moist dusty garage for 2 years and it had water in the oil last time we took it out (cracked center manifold) so that was my next thought, cam bearings, but would that effect oil pressure that much?, thanks again for everyones help and thoughts

 

Cam bearings will really affect oil pressure. I had a similar problem. I rebuilt my 327 and the heads were cleaned in a bead blaster. Well not all of the beads got washed out. Some made it in to the oil system and attacked the bearings and lifters. First I had low oil pressure, so I switched to a high volume pump. This helped but then I kept having lifters collapse. Seems that the beads were caught in the lifter oiling galleries. They ate the cam bearings then got caught in the lifters. After replacing a couple of lifters on 2 seperate occasions, I ended up pulling the motor. I then cleaned the oil galleries, replaced the crank and bearings(slight scratches). The cam bearings however were wasted. I replaced these too. Now its got 60psi on the road with a new stock oil pump, and 35 at hot idle. I dont think this is because of the crank bearings because the clearances were still tight, it just had a few heavy scratches from the beads.

Lesson learned clean everything 3 times!

 

yeah i hate to do it, but ill probably have to put $200 more into it, have it dipped and hot tanked and new cam bearings, and buy all the gaskets to put it back together, it was cold tonight so ill try the distributer tomarrow, oh well ill be careless for another 2 weeks, i think that miss is in the cap in rotor so hopefully ill get that fixed and run her for another week till i get the money for the internal work. thanks again

 

It wasnt the distributor, so me and my dad took out the motor and took it all apart (only took us 3 hours) and the cam bearings look fine, however, the first main bearing was missing about a 1/8 inch off the side, and some of the others were showing copper, so i am going to get new bearings and have it hot tanked and dipped, think that will fix the oil pressure??? thanks