Too much oil pressure

Posted By: '72CudaRacer

Too much oil pressure - 02/01/15 04:03 AM

I built a 500" RB for a customer, (stock block) and used the oil pump that was on the old engine. It's a Melling HV oil pump with a Milodon cover, single external line from a Milodon static pick up. When I primed the engine new, it had over 100 lbs of oil pressure. I replaced the oil pump regulator and spring with a new one from a Milodon overhaul kit. That brought the oil pressure down to about 85-88 lbs with a drill and priming shaft. I'd like it around 70-75 lbs idling. Whats the best way to bring this down?

Thanks,
Brian

Posted By: astjp2

Re: Too much oil pressure - 02/01/15 04:25 AM

non-HV pump

Posted By: old_racer

Re: Too much oil pressure - 02/01/15 05:27 AM

how about a spring from a stock pump? why would you want 70-75 lbs idling?

Posted By: 67DodgeCharger

Re: Too much oil pressure - 02/01/15 06:40 AM

Hot Rod has an article that covers the issue of too much oil pressure, except it being a chevy engine. The owner was breaking distributor gears from too much pressure from the oil pump and a very aggressive cam. The mechanic changed out the cam, lifters and I think the rockers, I have an old brain that works really good for an hour or less. The owner had a miss match of parts to compensate for problems of parts breaking, I would look at your setup and see if you are going to cause some problems with too much oil pressure.

Posted By: Cab_Burge

Re: Too much oil pressure - 02/01/15 08:26 AM

Quote:

I built a 500" RB for a customer, (stock block) and used the oil pump that was on the old engine. It's a Melling HV oil pump with a Milodon cover, single external line from a Milodon static pick up. When I primed the engine new, it had over 100 lbs of oil pressure. I replaced the oil pump regulator and spring with a new one from a Milodon overhaul kit. That brought the oil pressure down to about 85-88 lbs with a drill and priming shaft. I'd like it around 70-75 lbs idling. Whats the best way to bring this down?

Thanks,
Brian

I have cut and ground one to two coils off the high pressure springs in those pumps(mellings high volume) to get 60 to 70 lbs at or above 6500 RPM with hot thin (5W20WT) oil

Cut twice to avoid cutting to much the first time

Most BB Mopars will idle at or below 30 lbs less than when above 6000 RPM with hot oil

I like and use the old school rule of using 10 lbs. per thousand RPM with hot oil

Most of those high volume and high pressure pumps use the same bypass springs so they will usually bypass at or close to 80 lbs cold. Let us know what you end up doing and the resultant pressure

Posted By: BSB67

Re: Too much oil pressure - 02/01/15 02:31 PM

Quote:

I built a 500" RB for a customer, (stock block) and used the oil pump that was on the old engine. It's a Melling HV oil pump with a Milodon cover, single external line from a Milodon static pick up. When I primed the engine new, it had over 100 lbs of oil pressure. I replaced the oil pump regulator and spring with a new one from a Milodon overhaul kit. That brought the oil pressure down to about 85-88 lbs with a drill and priming shaft. I'd like it around 70-75 lbs idling. Whats the best way to bring this down?

Thanks,
Brian

Is it idling at 85 psi now, or priming at 85 now?

Posted By: dvw

Re: Too much oil pressure - 02/01/15 02:58 PM

What oil? What temp? Mine has over 100 psi cold with 5w30. Warm 25@1300, 65@7000. The drill won't tell you much.
Doug

Posted By: sr4440

Re: Too much oil pressure - 02/01/15 05:16 PM

On the dyno the priming pressure is always higher then what the running pressure is. Before i would "fix" it, I would start the engine and see where your at.

Joe

Posted By: Twostick

Re: Too much oil pressure - 02/01/15 06:09 PM

Quote:

I built a 500" RB for a customer, (stock block) and used the oil pump that was on the old engine. It's a Melling HV oil pump with a Milodon cover, single external line from a Milodon static pick up. When I primed the engine new, it had over 100 lbs of oil pressure. I replaced the oil pump regulator and spring with a new one from a Milodon overhaul kit. That brought the oil pressure down to about 85-88 lbs with a drill and priming shaft. I'd like it around 70-75 lbs idling. Whats the best way to bring this down?

Thanks,
Brian

That pressure will be considerably less once the oil is up to operating temp. Let it warm up and see where you're at.

75 PSI seems like a lot of pressure to me but if that is where you want it at hot idle, depending on how fast it idles, you may be putting the other spring back in.

Kevin

Posted By: Dodgem

Re: Too much oil pressure - 02/01/15 06:09 PM

This is what I use. Be forewarned back it off a bit when installing it mine went to 150LB on a milidon pump now maxes at 65 to 70 cold hot.
You want volume a small pump can't supply if it needs it hot under power so HV pump with right spring is just the ticket. On a HV pump in the old days I used to have 110 going out the end for 25 years don't hurt anything but using more power than needed.

http://www.manciniracing.com/milbrbadregk.html

http://www.summitracing.com/int/parts/mil-21550

Posted By: rickseeman

Re: Too much oil pressure - 02/01/15 11:53 PM

I agree or 440 Source sells theirs for $24.95.

http://store.440source.com/Adjustable-Oil-Pressure-Regulator/productinfo/200-1093/

Posted By: dart4forte

Re: Too much oil pressure - 02/03/15 05:53 AM

Too much oil pressure equals bad things

Filter could blow off or burst at the seams

Wash the bearings

Overcome the rear main seal

Is this a street motor?

Posted By: gregsdart

Re: Too much oil pressure - 02/03/15 03:35 PM

Stick with the original spring the pump came with, but like Cab said, shorten it a little at a time. It doesn't take much and is very easy to do. If you over shoot the mark, very thin shims behind the spring will bring it back up. I don't like the stock spring idea because someone else can come along and shim it, not knowing it is easy to put the spring into coil bind if you go too far. Then disaster strikes when the pressure goes off the chart.