410 Stoker help!!!! LOW OIL PRESSURE!!

[Mooch42]

• Did they put a new intermediate shaft at the distributor/pump gear to drive the oil pump?
• Was any info provided on how large they set the main and rod bearing clearances?
• PN's on main, rod and cam bearings?
• What are the idle RPM's and the actual RPM at which the oils pressure gets up to 40-50 psi when revved?

I believe they reused the oil pump shaft/distributor gear. As for the PN I don't have the paperwork the problem is this engine sat for 10yts after being built all I remember is its a eagle forged rotating assembly W/H-rods. The can is a Isky 292 mega can. It idles in park around 1200 rpm in gear just under 1000 rpm. If I hit the throttle rpm around 2g oil pressure is back up over 40psi. The problem is while it idles iiin gear the pressure starts to dip below 10psi

 

[mbaird]

its excessive bearing clearances is my guess. 20/50 is really heavy for this kind of motor. The heavy oil is patching things until it gets hot (thinner).

I hope I am wrong....
What did the machine shop say?

 

[j par]

I believe they reused the oil pump shaft/distributor gear. As for the PN I don't have the paperwork the problem is this engine sat for 10yts after being built all I remember is its a eagle forged rotating assembly W/H-rods. The can is a Isky 292 mega can. It idles in park around 1200 rpm in gear just under 1000 rpm. If I hit the throttle rpm around 2g oil pressure is back up over 40psi. The problem is while it idles iiin gear the pressure starts to dip below 10psi

Does the dip happen at 1200 RPM or at 1000? Is the idle extremely choppy?

 

[Mooch42]

its excessive bearing clearances is my guess. 20/50 is really heavy for this kind of motor. The heavy oil is patching things until it gets hot (thinner).

I hope I am wrong....
What did the machine shop say?

I was running a 10/30 same oil pressure numbers I switched to 20/50 to see if it would help. All the shop said is they build street engines with a tighter clearance.

 

[Mooch42]

Does the dip happen at 1200 RPM or at 1000? Is the idle extremely choppy?

It holds about 15psi in park (1200rpm). Yes it has a rough idle but oil pressure should never be this low it hasn't even loosened up yet

 

[nm9stheham]

If the change in the viscosity truly did not change the pressures, and this is reaching 40 psi back pressure in the system at 2k RPM, then this sounds more like a low flow/oil supply problem out of the pump. I would be looking at the pump, pickup and/or pump drive.

 

[Mooch42]

If the change in the viscosity truly did not change the pressures, and this is reaching 40 psi back pressure in the system at 2k RPM, then this sounds more like a low flow/oil supply problem out of the pump. I would be looking at the pump, pickup and/or pump drive.

I think I'm going to pull the front of the motor apart and make sure the galley plugs are under the cam plate if they are maybe change the oil pump

 

[j par]

Thinking out loud I just keep thinking the pump. That keeps leading back to their. For curiosity sake I would like to hear an argument against it being the pump?

 

[Mooch42]

Thinking out loud I just keep thinking the pump. That keeps leading back to their. For curiosity sake I would like to hear an argument against it being the pump?

I was also thinking the pump but I talked to another very reputable shop. He says if the pressure spring in the pump was bad/stuck open I wouldn't have any oil pressure

 

[j par]

I was also thinking the pump but I talked to another very reputable shop. He says if the pressure spring in the pump was bad/stuck open I wouldn't have any oil pressure

Thinking Out Loud again maybe a blockage to the pump....

 

[PRH]

I like the “pull the intake and run the oil pump” plan.

With a HV pump it should have tons of pressure.

I had a HV pump with a piece of debris in the pressure relief valve, not allowing to open.
You’d be shocked at how much pressure those things will generate.

 

[PRH]

You say it’s 40psi@2k.

What is it at 5 and 6k?

15-20 years ago when I was doing circle track small blocks, I stopped using the HV pumps.
The motors had well over 100psi with them.
At the time, a regular M72 would provide 70-80psi at high rpm.

 

[Mooch42]

I like the “pull the intake and run the oil pump” plan.

With a HV pump it should have tons of pressure.

I had a HV pump with a piece of debris in the pressure relief valve, not allowing to open.
You’d be shocked at how much pressure those things will generate.

I am going to start with the intake the I think the galley plugs in the front of the engine under the thrust plate.

You say it’s 40psi@2k.

What is it at 5 and 6k?

15-20 years ago when I was doing circle track small blocks, I stopped using the HV pumps.
The motors had well over 100psi with them.
At the time, a regular M72 would provide 70-80psi at high rpm.

I haven't spun this engine to 5k yet. As soon as I let it idle after the cam breakin a noticed the low oil pressure

 

[fishmens67]

You say it’s 40psi@2k.

What is it at 5 and 6k?

15-20 years ago when I was doing circle track small blocks, I stopped using the HV pumps.
The motors had well over 100psi with them.
At the time, a regular M72 would provide 70-80psi at high rpm.

This is what I have witnessed. almost enough to blow the oil filter.

 

[j par]

This is what I have witnessed. almost enough to blow the oil filter.

I don't know I think the oil filter that I use is rated up to like 200 PSI...

 

[furrystump]

Is it a roller cam? I know you said Isky, but not if it is a roller. It could be uncovering the oil hole on a roller lifter.

 

[Mooch42]

Is it a roller cam? I know you said Isky, but not if it is a roller. It could be uncovering the oil hole on a roller lifter.

Flat tappet cam

 

[doogievlg]

Make sure the oil isn’t fuel diluted. I had the same problem on the 390 stroker and that was my issue. Carb would drip out of the secondary boosters when engine was off. Exact same pressure as described.

This happened to me and I didn’t catch it in time.

 

[Mooch42]

This happened to me and I didn’t catch it in time.

View attachment 1715270331

I checked the oil it isn't over full. How did you figure out it was deluted so bad

 

[PRH]

This happened to me and I didn’t catch it in time.

View attachment 1715270331

Good reminder........ pull the oil filter and cut it open.
See if there’s any bearing material in it.

 

[superchargeddrt]

I think I am gonna pull the intake tomorrow and run the oil pump with a drill to see if I see anything like that

Oil will only come out at the lifters when the camshaft is in a certain position. You will be have to SLOWLY rotate the engine until you see oil.

 

[Mooch42]

Good reminder........ pull the oil filter and cut it open.
See if there’s any bearing material in it.

No bearing material in the filter

 

[PRH]

When you’re priming it, make sure the oil appears air bubble free.

I put a SB together once where the oil had tiny air bubbles in it while priming.
The cap retaining the spring in the oil pump had a leak and was introducing air into the pump.
I caught it before running the motor, but I have to believe that would have impacted the hot pressure.

 

[fishmens67]

I don't know I think the oil filter that I use is rated up to like 200 PSI...

LMAO it was just a statement. Too many times these oil pressure threads don't make sense as to what pressure in engines using various pumps has been.

 

[nm9stheham]

I like the “pull the intake and run the oil pump” plan.

With a HV pump it should have tons of pressure.

I had a HV pump with a piece of debris in the pressure relief valve, not allowing to open.
You’d be shocked at how much pressure those things will generate.

Yes, it SHOULD have tons of pressure....(And yes, I have indeed pumped a pan dry in racing, and blown a filter gasket off the seat, with a too high a pressure relief valve setting.)

At the lower RPM's the oil flow from the pump drops and drops, and, in the OP's case, the pump flow is dropping a level where the back pressure with that specific pump's flow capacity at that RPM and into that particular engine is dropping sharply. If the OP has a 'loose' engine for clearances, then how the pump and system interact at low RPM's will depend on the specific pump flow.

My thought is that he just may have a particular pump with some clearances that are not tight, and/or a poor pickup situation, either of which is compromising low RPM flow. A loose clearanced or worn pump will seriously drop some % of its flow; I used to change pump covers and aluminum pump housings on a particular engine regularly, and bingo, the tight clearances would really boost flow and pressures particularly at low RPM's.

Oil will only come out at the lifters when the camshaft is in a certain position. You will be have to SLOWLY rotate the engine until you see oil.

I believe you meant to say 'at the rockers'; the lifters get pressure around them all the time.