Have just completed a total rebuild on a 1957 371 cu. in. motor. Problem that I have is low oil pressure.
Oil is getting to top end but not very well. I installed an oil pressure guage and was getting 20 lbs of pressure where it should be 35-45 lbs.

I had a kit put in the oil pump at time of rebuild so decided to get a new oil pump and try that. Result of that was even worse. I am now getting 16-17 lbs oil pressure.

Any ideas or suggestions to look for problem will be appreciated.

Thanks
Trainmaster

 

What RPM are you getting these readings at? If it's idle, then while not optimal, the pressure is not dangerously low.

 

The oil pressures quoted above are at idle and revved up. Just not enough oil getting to the hydraulic lifters and the rockers. After running for a while and turning off I can push down on some of the rockers without much resistance. I have oil on the top end but it should be coming out and spraying around a bit but that is not the case. I can run it with the valve covers off and see the oil flow but it isn't really spraying around.

 

I have quite a bit of lifter noise even with the valve covers on. Motor was professionaly cleaned and was just wondering if there is a plug they may have taken out that I have missed??

 

Welcome to C.O. That pressure seems very low, I know my '55 runs a steady 45 @ 50mph and up. Wish I could give you the probable reason, but I'm sure someone else will have good advice. Larry

 

Cleaned? You mean an exterior steam clean or pressure wash? How was the oil pressure before this was done?

 

There is a chance that a oil galley plug was left out during reassembly. The restriction plug that supplies oil to the distributor comes to mind, if left out it will cause a problem like mentioned.... Tedd

 

Can you tell me or send a diagram of where the oil restriction plug for the distributor is located on a 371 cu. inch.

 

Had a similar problem with my 59, the rear oil galley plug was not in place. Could be seen if you pull the distributer and use a inspection mirror. In my case though oil pressure was about 4psi, just enough to keep the oil pressure light off. The engine would barely run and lifters would not pump up.

 

These first generation Old's motors don't sling oil around the valve train area like a SBC but your oil pressure does appear low for a new re build. It's to bad that you didn't plastic gauge the rods and mains when you installed the new oil pump that would tell if you have a clearance problem.... Tedd

 

If you are indeed getting oil pressure at or near 20 lbs I would think that that would be enough to pump up the lifters.Are you sure what you are hearing is lifter clatter? Have you ran the engine long enough? Sometimes it takes quite a while for these engines on the first start up to get oil to the upper valve area.

Do you get very much fluctuation in oil pressure from Idle to say 2000 RPM. There may not be a problem here at all..... Tedd

 

Was finally able to get time to check on the oil galley plug behind the distributor, sure enough it is gone and there is a threaded hole there. When the block was cleaned, (Acid Bath) the company must have removed the plug and not replaced it back into the block. Gonna try to see if I can finagle a plug in there without tearing everything down again. With that in place I should resolve my issue. Thanks for all of the comments on what to look for because I was at a loss. Also will be talking to the professionals that cleaned the block as this was their mess up. Thanks again.

 

That Plug should have a 1/16 inch hole in the center of it, it's not just a smooth plug. It's purpose is to oil the distributor gear so it does need some oil to pass through it.

I don't remember it being threaded but it's been a while since I have been there so check with your builder or Tony at Ross Racing if someone here doesn't know.... Tedd

 

Pretty sure the plug is threaded, it was a long while since I did mine but I got the missing plug from my spare 394. Cant remember if it had a hole.

 

Looks like I may have to take the motor out to do this and tear down again. Son of a B. I never took that plug out so Company that did the bare block removed it and forgot about it. Of course now they deny that. I'll keep you posted. Really appreciate the help with this.

 

Got the plug installed without pulling the motor so when I get it all back togther hope that is it.

 

Best of luck!

 

let us know how it comes out. Glad you got that plug in without having to pull the engine, that had to be a tight job. Just for my own information and a memory check on my old brain did the plug have a small hole in it or am I thinking of a different engine altogether... Tedd

 

Plug had a small hole in it to allow oil to get to distributor gear. I have great oil pressure now. Purring like a kitten. Thanks for all of your help.

 

Hi , i was just checking my lifters, and i wonder if i can see this “plug” from the valley area.?
when i pulled the valve covers, i did not noticed a good oil flow. found one lifter clogged up, and wanting to make sure i have this plug installed.. thnks

 

Look down the distributor hole with a dental mirror I don't think you can see it from the valley area..... Tedd

 

I had to pull the distributor and then check with a mirror to see if the plug was there. In my case the oil restrictor plug was missing and was able to install it with out tearing down the motor.