Help with low oil pressure

[moparmike68]

It is weird to have to tell a seasoned shop "how to build", but they often have younger inexperienced guys doing much of the work now. In my case, I trusted the local builder to assemble my stroker. They did just that, assemble. My bearing clearance must be quite large due to the low oil pressure. The old saying of "trust and verify" applies here. I trusted but did not verify. They built engines for us in the past that were excellent.

Well this was an older guy that had an older shop with machines visible so I thought I was good. I thought”oh this guy is older and wiser and is probably good at rebuilding g engines over decades.Not too sure now🫩. You just never know

 

[Ricks72Chlgr440]

Well this was an older guy that had an older shop with machines visible so I thought I was good. I thought”oh this guy is older and wiser and is probably good at rebuilding g engines over decades.Not too sure now🫩. You just never know

Exactly. The shop I use is always really busy so thinking they just quickly built it and out the door. It takes a little longer to use plastigauge for bearing clearance but I doubt it was done. I know Mopar Joe said one time he sent back bearings in a stroker kit because they did not provide the correct clearance. It can happen, but machine shops should check for that.

 

[moparmike68]

Exactly. The shop I use is always really busy so thinking they just quickly built it and out the door. It takes a little longer to use plastigauge for bearing clearance but I doubt it was done. I know Mopar Joe said one time he sent back bearings in a stroker kit because they did not provide the correct clearance. It can happen, but machine shops should check for that.

No kidding

 

[rickseeman]

You said in your first post that you tried a high volume pump and it made no difference. I'm finding that hard to believe. I'm a B/RB oil pump guy. A HV pump is 1/4" thicker than a stock pump. Is that what you put on there? Last week I finished up a 383 rebuild. When I put it on the test stand it had low hot oil pressure idling. So I put a HV pump on and now it has 30-40. The engines in our classic Mopar muscle cars are over 50 years old. There are problems associated with this. One recurring theme you will hear about on the forums every month is “low hot oil pressure idling”. Yes it’s true, you have low hot oil pressure idling. Don’t panic. Your engine is not going to “blow up”. It will still make plenty of oil pressure when you are driving because the oil pump is turning more rpm’s. But when you are idling the engine might be turning as low as 700 rpm’s. That means your oil pump is turning 350 rpm’s. Engines wear. Even though your engine has been rebuilt, there are 16 lifter bores that are worn and there's a lot of oil passing each lifter. Factory rod and main bearing clearances were very tight. A rebuild today likely has more clearance. Your problem is very common. A M-63HV usually fixes the problem. If not you can go to thicker oil. (By the way, the stock spring is red or pink, usually will bypass around 55 psi. The black spring, sometimes called the hemi spring, bypasses around 75 psi. Use whichever spring you like.)

 

[AUSTA]

What is the idle speed how far does the pressure come up by increasing idle speed

 

[moparmike68]

You said in your first post that you tried a high volume pump and it made no difference. I'm finding that hard to believe. I'm a B/RB oil pump guy. A HV pump is 1/4" thicker than a stock pump. Is that what you put on there? Last week I finished up a 383 rebuild. When I put it on the test stand it had low hot oil pressure idling. So I put a HV pump on and now it has 30-40. The engines in our classic Mopar muscle cars are over 50 years old. There are problems associated with this. One recurring theme you will hear about on the forums every month is “low hot oil pressure idling”. Yes it’s true, you have low hot oil pressure idling. Don’t panic. Your engine is not going to “blow up”. It will still make plenty of oil pressure when you are driving because the oil pump is turning more rpm’s. But when you are idling the engine might be turning as low as 700 rpm’s. That means your oil pump is turning 350 rpm’s. Engines wear. Even though your engine has been rebuilt, there are 16 lifter bores that are worn and there's a lot of oil passing each lifter. Factory rod and main bearing clearances were very tight. A rebuild today likely has more clearance. Your problem is very common. A M-63HV usually fixes the problem. If not you can go to thicker oil. (By the way, the stock spring is red or pink, usually will bypass around 55 psi. The black spring, sometimes called the hemi spring, bypasses around 75 psi. Use whichever spring you like.)

Thanks for your info! To be honest , my memory may be a little fuzzy as it was about 10years ago that I had the rebuild done. I thought that I had tried both a high pressure, and a high volume pump, but looking at the two pumps I have, they look identical size(only difference is the springs. One is pink, the other possibly black or no color). One has the small tag “m63 hp” on the bolt. The other has no tag. I’m now thinking that I have a stock pump and and a high pressure pump. So I guess I did not try a high volume pump. . What is your opinion on the fears stated by people on the forums, that a HV pump could suck the stock pan dry? I have a stock pan with windage tray. I don’t race the car and will occasionally take it out on the road/highway for a blast or two to “blow the carbon out”. My next plan was to try my current pump and change from Brad Penn 10w30 to valvoline 10w40 racing oil and see if that helps the pressure. If not, then I may try the hv pump.
Thanks!

 

[moparmike68]

What is the idle speed how far does the pressure come up by increasing idle speed

I don”t remember, since it was last spring/summer when I last drove it. I believe it was around 700-800rpm and the pressure did increase with acceleration/increased rpm’s but I often wasn’t paying too much attention to the upper pressure , but instead the extremely low end pressure.

 

[Challenger RTA]

700-800rpm

Not that this is the problem but it's misunderstood. For one thing you not driving a Diesel. Diesel are built in a manner to idle for hours if need be. A car engine is built to start at high idle to warm up and run. Not to sit an idle. That is one of the hardest things on them. 700-800 rpms that just bothers me but it might be ok. The pump isn't spinning that fast. When I prime an engine I use a 3600 - 1600 rpm drill on the lower speed for toque. check out below. You can see how long it takes to get the oil there. You can her the Milwaukee drill zinging away. Made in the USA.
By the way and it still runs since 85.

 

[moparmike68]

Not that this is the problem but it's misunderstood. For one thing you not driving a Diesel. Diesel are built in a manner to idle for hours if need be. A car engine is built to start at high idle to warm up and run. Not to sit an idle. That is one of the hardest things on them. 700-800 rpms that just bothers me but it might be ok. The pump isn't spinning that fast. When I prime an engine I use a 3600 - 1600 rpm drill on the lower speed for toque. check out below. You can see how long it takes to get the oil there. You can her the Milwaukee drill zinging away. Made in the USA.
By the way and it still runs since 85.

Thanks

 

[rickseeman]

Thanks for your info! To be honest , my memory may be a little fuzzy as it was about 10years ago that I had the rebuild done. I thought that I had tried both a high pressure, and a high volume pump, but looking at the two pumps I have, they look identical size(only difference is the springs. One is pink, the other possibly black or no color). One has the small tag “m63 hp” on the bolt. The other has no tag. I’m now thinking that I have a stock pump and and a high pressure pump. So I guess I did not try a high volume pump. . What is your opinion on the fears stated by people on the forums, that a HV pump could suck the stock pan dry? I have a stock pan with windage tray. I don’t race the car and will occasionally take it out on the road/highway for a blast or two to “blow the carbon out”. My next plan was to try my current pump and change from Brad Penn 10w30 to valvoline 10w40 racing oil and see if that helps the pressure. If not, then I may try the hv pump.
Thanks!

I wouldn't worry about "sucking the pan dry". Get a M-63HV pump and put your pink spring in it. This should bypass around 55 psi and give you better hot oil pressure idling. If the 10-40 oil doesn't work you can try 20-50. We know your engine has a lot of clearance.

 

[moparmike68]

I wouldn't worry about "sucking the pan dry". Get a M-63HV pump and put your pink spring in it. This should bypass around 55 psi and give you better hot oil pressure idling. If the 10-40 oil doesn't work you can try 20-50. We know your engine has a lot of clearance.

Thanks