[leejoy]

Guys

need help again with my 72 Street car.

question about oil pressure. When I startup my freshly built (about 500 miles) 468 chevy, the oil pressure is high - around 50-70 PSI. It stays like that until the block and oil warm up at which time the pressure drops to about 30 psi. Even at like 2500 rpm - it's still like 25-30 PSI. Is that ok or not? Kind of worries me - I don't want to damage bearings and tear the whole fricking thing apart to repair it. I do notice that sometimes (during acceleration and braking) the oil pressure rises another 10-20 PSI for a few seconds and then drops again - kind of weird - havent established an exact patter on that yet.

Doesnt low oil pressure (assuming the oil pump is good and filter is clean) indicate excessive bearing clearances?

I think I'm running standard 10W-30 in that thing right now. Would a thicker oil help? Would Synthetic oil help? Are my bearings too loose?

thanks guys

Lee

 

[fabio]

What's your oil pressure around 5 grand? Generally they say for every 1k of rpms you need 10 psi of oil pressure. Some run even lower oil pressure that this # so you should be fine. Btw is this just a standard oil pump?

 

[leejoy]

What's your oil pressure around 5 grand? Generally they say for every 1k of rpms you need 10 psi of oil pressure. Some run even lower oil pressure that this # so you should be fine. Btw is this just a standard oil pump?

with regard to the type of oil pump, I'm embarassed to say " I don't know". I rebuilt the long block on this motor last year. I got the motor from some other guy 4 years ago. He rebuilt the short block. I never pulled the block from the car so I don't know about the oil pump - probably stock. I also don't know if this is a 2 or 4-bolt block (embarassing I know) however I do know the front main cap is a 2-bolt so I am guessing the block is a 2-bolt.

If 10 PSI per 1000 RPM is fine I might be ok. I'll take her out and run her again later this week and watch the OIL PSI at 3000-5000 rpm and see what she does.

Lee

 

[Billy177]

try some 15w40 oil and your pressure should go up

 

[fabio]

try some 15w40 oil and your pressure should go up

ya you should be running a good diesel oil like chevron delo, shell rotella, or mobil delvac. Also run a good oil filter like wix or napa gold(made by wix).

 

[fastyellowss]

Some motor oils dont keep there oil pressure as long as others. Use a good oil like Castrol 10/30. Ive used others and had the same prob, but not with the Castrol. Thats my preferance.

 

[gnicholson]

If I under stood you right I would be worried about the pressure going up during accel/decell.sounds like a cavitation problem.

 

[jloshotz]

I also don't know if this is a 2 or 4-bolt block (embarassing I know) however I do know the front main cap is a 2-bolt so I am guessing the block is a 2-bolt.
Lee

Don't go by that Lee, I'm fairly certain most if not all factory 4 bolt blocks have front and rear 2 bolt caps (Doesn't answer your question, just thought i'd toss that in)

 

[ironhead]

Don't go by that Lee, I'm fairly certain most if not all factory 4 bolt blocks have front and rear 2 bolt caps (Doesn't answer your question, just thought i'd toss that in)

That applys to the small block.Factory 4 bolt main big blocks have 4 bolts on all the mains.

 

[2cool]

Hope your pickup tube is not loose.

 

[leejoy]

Don't go by that Lee, I'm fairly certain most if not all factory 4 bolt blocks have front and rear 2 bolt caps (Doesn't answer your question, just thought i'd toss that in)

thanks for the optimistic opinion, but everytime somebody like yourself suggest that 4-bolt 454 blocks may have 2-bolt front and rear main caps, another guy chimes in and says that is not true. so let the debate begin again.

Lee

 

[leejoy]

Hope your pickup tube is not loose.

oh, no - please don't suggest that. Nothing could be worse. I'd have to basically pull the motor to repair that right? - I think I'd rather sell the car if I had to do that again. no thanks.

Lee

 

[2cool]

Did you seat it all the way in, can be hard to do sometimes?

 

[gnicholson]

with the oil pressure fluctation you mentioned i would look at a cavitation prob. like i mentioned earlier.pick up improperly located or air leak in the pickup. you can pull the pan without removing the engine

 

[2cool]

10lbs per 1000rpm is correct but it should it 40-50 just off idle if you used a screw driver to install the pickup you could have put a small hole in it.
I have no idea how you could test it other than to remove the distributor and install a primer pump and see how it feels.

 

[von]

Make sure your gauge is accurate. You might try another temporary gauge for a 2nd opinion.

 

[Chevelle 6-71]

Hope your pickup tube is not loose.

If all else fails in your attempt to find this problem, & I hope this is NOT it, the pick tube may be loose or destroyed in the bottom of the pan. My last 350 lost the tube, had the exact same pressure problem and shredded the parts in the bottom of the pan. I hope that is not it. Good Luck.

 

[leejoy]

If all else fails in your attempt to find this problem, & I hope this is NOT it, the pick tube may be loose or destroyed in the bottom of the pan. My last 350 lost the tube, had the exact same pressure problem and shredded the parts in the bottom of the pan. I hope that is not it. Good Luck.

Ok - I will keep an eye on it next time I drive it and watch for more clues and data. If it's the pickup tube I will just shoot myself and get it over with.

Lee

 

[Busted Knuckles]

ALL factory 4-bolt 454 blocks have 4-bolt main caps on all 5 positions, ALL factory 2-bolt blocks have 2-bolt main caps at all 5 positions. If a big block has 4-bolt caps in the center 3 positions only, it's a conversion.

 

[von]

If the pickup is too close to the pan bottom it can cause pressure fluctuations from oil starvation. You might be able to tell with a light through the drain plug hole or by jiggling a stiff wire between pickup and pan if nothing else.