460 King Cobra oil pump

[Trevthefox]

Hello everyone,

In a week or so I'm pulling the engine to replace a cam shaft in my '89 460 King cobra. While out in the water I noticed that my oil pressure would drop significantly at higher rpms. (sorry I don't have the specifics but I remember it was in the 40psi range at higher rpms). It worries me that I could ruin a brand new cam if I don't solve this oil pressure problem

1st step tonight was to run the engine and put a mechanical gauge on it. Per the manual the oil pressure should be at 40-60 psi at 800 rpm and 50 - 80 psi at 2000 rpm. My engine was at 53 psi at 800 rpm and 60 psi at 2000 rpm. I know the engine is falling within the the limits according to the book but should the psi be higher? One thing to note is that when doing this test we had to do it rather quickly so the engine hadn't fully heated up.

I just figured since the motor will be out we might as well replace the oil pump since it's pretty old. Will a standard pressure oil pump for a 460 suffice or does it call for a high volume/pressure oil pump?

 

[Scott Danforth]

unless you modified the motor for more RPM's or more power, a standard 460 truck oil pump is fine. I suggest a melling.

however the mechanical oil pumps them selves normally do not go bad. you may simply have a bad pickup or a stuck PRV

 

[kenny nunez]

It may be that the pieces of metal from the worn cam are stuck in the oil pump screen. Make sure to always add the zink additive supplement to the oil at every oil change or you will be getting real good at replacing the cam.

 

[racerone]

Well----If there are --" pieces of metal " ---on an oil pump screen there are more problems than a worn cam.

 

[Lou C]

Also if you can find it, Lucas Marine oil is a lot higher in Zinc than any of the other widely available marine oils. Might want to see if you can find it. With the roller cams on the newer GM based engines its not needed but with a flat tappet I'd probably use that.

TDS_Marine-Oil-SAE-20W-50.pdf (lucasoil.com)

Zinc_Values_MotorOil-MotorcycleOil_5-7-19 (lucasoil.com)

 

[Trevthefox]

unless you modified the motor for more RPM's or more power, a standard 460 truck oil pump is fine. I suggest a melling.

however the mechanical oil pumps them selves normally do not go bad. you may simply have a bad pickup or a stuck PRV

I read about having a stuck PRV and the book gives some specifics on spring tension but in the manual it didn't really go into detail on how to check it. Any tips?

 

[Trevthefox]

It may be that the pieces of metal from the worn cam are stuck in the oil pump screen. Make sure to always add the zink additive supplement to the oil at every oil change or you will be getting real good at replacing the cam.

Yes we made sure to use the zinc additive. I'll check the pan and the pickup screen when we swap the cam.

 

[Trevthefox]

Well----If there are --" pieces of metal " ---on an oil pump screen there are more problems than a worn cam.

fingers crossed

 

[Trevthefox]

Also if you can find it, Lucas Marine oil is a lot higher in Zinc than any of the other widely available marine oils. Might want to see if you can find it. With the roller cams on the newer GM based engines its not needed but with a flat tappet I'd probably use that.

TDS_Marine-Oil-SAE-20W-50.pdf (lucasoil.com)

Zinc_Values_MotorOil-MotorcycleOil_5-7-19 (lucasoil.com)

We've been using just regular sae 30 with a zinc additive bought from autozone

 

[Scott Danforth]

I read about having a stuck PRV and the book gives some specifics on spring tension but in the manual it didn't really go into detail on how to check it. Any tips?

pull threaded plug with spring and piston. piston should move freely.