Oil pressure

I continue to slowly work toward getting my 73 back on the street. I recently replaced the 429 with a 460 stroked to 528. I initially had cooling and timing problems that are mostly sorted out thanks to the help of members on this forum. I have driven it a few times around the block, but mostly still started and run at idle. My current conundrum is low oil pressure at operating temperature ( 190-205) I generally have low Oil pressure with it being about 15 at idle on startup and it drops to 3-5 PSI at hot idle ( 850 RPM) . I am using 20-50 and that helps ( was zero with 10-30). As RPMs go up oil pressure goes up as well but not as much As I am used to seeing. about 15 PSI at 2000 RPM and maxes out at 50psi at 6500 RPM. I am using a mechanical oil pressure gage and the mechanical gage on the dash is in agreement with a hand held gage attached in the factory location, so unfortunately it is not a bad sending unit. The oil pump is new OEM Ford pump for 429 front sump 8.5" deep Pan. dipstick reads full at 7 Qts with filter ( I think it is supposed to be 6.8Qt). pressure increase with RPM so not starved, new pan new pickup clean engine . I guess there could be a bad relief valve or other internal leak / manufacturing defect in the pump but I think that it is mostly just a loose engine-- Long story --The engine was purchased from a local shop and was built in the 90s for use in a tube chassis Fairlane dragster I changed the CAM to it to make it more street-able ( but still solid roller cam -- I did not want to get new valve train) , but at that time race engines were built looser than they are today The actual builder has since passed away, but I am told he typically built with .003 on the rods and .004 on the mains. Finally even when the oil pressure is reading 3psi-- There is good flow to the rockers and pushrods - I put an inspection camera through the vent holes in the valve covers.

My question is should I replace the pump with a normal pressure high volume pump -assuming that the oil is just returning to the pan faster than the pump can keep up or should I use I high pressure pump with the goal of increasing pressure but not changing volume ( or Both high pressure and high Volume) this is an overpowered street car so loosing a few HP to the oil pump is not a big concern). Or should I just keep it the way it is?

As you stated .003 rod clearance is definitely on the very high side for a street engine but not extreme for your big engine. However your .004" mains are really going to gush oil. Your 20-50 oil is certainly a good choice with the engine clearances. I personally would not be concerned at all with your 50psi hot oil pressure at 6000 RPM's. Additionally, while 5-10 psi idle pressure is frightening to some classic car owners, many "Modern" cars run single digit oil pressure at idle because thats really all you need at low idle RPM's.
My opinion is run a HV pump for sure and in the near future drop the oil pan and pull a couple main and rod caps to check to bearings for wear. If all looks good, have fun with it!

Thanks for the reply. I was tending think HV pump was best way to go, but there is so much controversy on the best solution to this problem.

Doc302 said:

Thanks for the reply. I was tending think HV pump was best way to go, but there is so much controversy on the best solution to this problem.

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I'll agree with Cleveland Crush here. With those bearing clearances, you'll need the extra volume.

The controversy tends to center around people wanting to run an HV pump with factory bearing clearances. All that does is chew up a bunch of power since anything that can't make it to the galleys gets dumped out the bypass.

If the bearing clearances are indeed too loose for your application, sufficient volume is a bigger concern that the pressure. However the pressure readings you stated would still be of significant concern, especially since you are using solid roller lifters on the street. Given their age, they are likely needle bearings and no direct oiling, so a lot of oil should be delivered to them, even at idle and cruising RPM. A lifter needle bearing failure can cause a lot of damage. Chuck

Just so I could sleep at night, I would consider dropping the pan and pump and inspecting the by-pass piston in your pump. That poppet can stick, sometimes in a partially open/closed position, bleeding off pressure. It's been known to happen, and worth checking. if it is stuck, or has some foreign grit in it, simply clean your pump, kiss the by-pass bore with some scotchbrite on a flapper stick. Whether or not that's the issue, it should only cost you some oil and a pan gasket,....oh, and a few curse words.

you might try to add an external oil line ,like 3/8" tube from the oil filter area back to the oil pressure port at the back of the motor. this will give higher pressure at the rear end of the crankshaft and a higher reading on your gauge so you wont worry so much.

I got one of these for my 351c

I would do it again as they take a stock pump and smooth/blueprint it before they add their oarts

I have an idle of 80 cold and 30-40 hot with 20/50. I have the external oil line added to mine also

They build to order so expect some delays.

I definitely would buy again.

https://www.schumannoilpumps.com/Fo...il-Pump-BBFPXVGPB-Schumann-Oil-Pumps_8293.prt

This is another source of blueprinted oil pumps. I got one for my Cleveland a few months ago.
However, I would look into your bearing clearances first.

https://stores.precisionoilpumps.com/ford-429-460/

c9zx said:

If the bearing clearances are indeed too loose for your application, sufficient volume is a bigger concern that the pressure. However the pressure readings you stated would still be of significant concern, especially since you are using solid roller lifters on the street. Given their age, they are likely needle bearings and no direct oiling, so a lot of oil should be delivered to them, even at idle and cruising RPM. A lifter needle bearing failure can cause a lot of damage. Chuck

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Thank you I think I will plan to replace the pump with High Volume -- If I can find one- they all seem to be for trucks with rear sump.

rcadd1ct said:

I got one of these for my 351c

I would do it again as they take a stock pump and smooth/blueprint it before they add their oarts

I have an idle of 80 cold and 30-40 hot with 20/50. I have the external oil line added to mine also

They build to order so expect some delays.

I definitely would buy again.

https://www.schumannoilpumps.com/Fo...il-Pump-BBFPXVGPB-Schumann-Oil-Pumps_8293.prt

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Thank you I will check them out,

If you are going to go to the trouble of removing the engine to change the oil pump why not just address the root cause and correct the clearances?

There are three pump styles made for the 385 series engines

M84D - rear facing bolt on pickup - used for mid and rear sump applications

M84 - vertical hole for press in pickup - used for passenger car applications

M84B - 45° downward facing bolt on pickup - used for 429CJ and 429/460 Police Interceptor applications - you must check pickup to pan clearance

https://www.rockauto.com/en/catalog/ford,1971,mustang,7.0l+429cid+v8,1132715,engine,oil+pump,5564

Hemikiller said:

There are three pump styles made for the 385 series engines

M84D - rear facing bolt on pickup - used for mid and rear sump applications

M84 - vertical hole for press in pickup - used for passenger car applications

M84B - 45° downward facing bolt on pickup - used for 429CJ and 429/460 Police Interceptor applications - you must check pickup to pan clearance

https://www.rockauto.com/en/catalog/ford,1971,mustang,7.0l+429cid+v8,1132715,engine,oil+pump,5564

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If you have the pan off why not change the rod and main bearings to improve the clearances? My machine shop set my established clearances as I mentioned that the car was a street driven Mustang. I went around and around and insisted to to fellow who assembled the short block that the engine was for the street and leave it alone. He is used to assembling race motors which are all blown up sitting in his shop that I noticed. He was a real bone head. We butted heads for 5 months before I decided to bring the engine home to finish assembly. This is the first Ford engine that I have worked on and wanted to spend the time on body work. Thx, Bill