oil pump help

[Ed Wright]

If Adger says differently, I will defer to Adger. But, why would anybody think they need a high volume oil pump? I never understood why they are even made & offered.
I took a break from drag racing for a couple of years about 1972, to build my business. I was closed too many week days for travel. I had helped a couple of local dirt track guys, and decided to try that, because it was just Saturday nights right here in town. At the time they weren't allowed dry sumps. 310" limit, wet sumps & carbs. Most were using high volume pumps just because after 25 to 50 laps oil pressure at idle dropped to 15 or 20 psi. Big deal. They wore brass dist gears & camshaft oil pump drive gears like crazy.
Oil filters always full of that that crap as well. I just used the std volume Moroso blueprinted pump from my last C/SM engine, same short block I started with. Zero problems. Just changed the heads, Carillo rods, cam & oil pan. Won some A features the first year.
I changed the pumps in the engines I helped guys with. Had a sharp local machinist cut the gears old camshafts, and put them on the cams they had killed, press fitted with a dowel pin. Stopped all those issues. Bearings stayed nicer without that crap going through them.
I, and a LOT of us, use Larry Stewart LOW volume pumps now. My second choice would be the Moroso blueprinted pump.

[Ron Gusack]

Please help me understanding the whole volume issue. I've always thought this:
Pressure is what determines how much power is required to turn the pump.

Pressure is determined by excess volume and the bypass spring.

If you have a HV pump with the same pressure under the same conditions as a SV pump, the same amount of power will be required to operate the pump. No???

If I put a lower pressure spring in my HV pump, wouldn't I pick up some power??

I just tested my M77HV vs the 22150 Moroso race SV pump. The HV pressure was 70 and quickly dropped to 65, then 60. The Moroso was bouncing between 55 and 50. The HV has the bypass oil returning to the pan and the Moroso doesn't. I'm assuming the bouncing is because of the return differences in the caps. I need to figure out how to drill the cap on the Moroso SV and retest. This was with 10-30 oil at 46 degrees.

[Ed Wright]

Ron, from what I saw with the local circle track cars, I would say you are mistaken. I posted what I observed. More power required to run the big pump is the only thing I know of that would wear gears like that. Old as I am, I haven't seen everything yet.

From your description of the oil pressure you are seeing, I would say you problems other than the pumps. I just put a new Moroso std volume pump in my spare engine, which I recently sold. Oil pressure was solid at 60 psi all the time. Hot or cold (5W20) idle or WOT. You have something wrong somewhere.

I have an old rear main cap, with a gauge on it. I bolt my pumps on it, drop it in my parts washer, and spin it with a 1/2" drill to see where the relief valve is set. Whatever it shows there, is what it shows in the car. My thinking is solvent, being thin, would be similar to hot, thin weight oil.
I noticed solvent spraying out from the area where the pump mounts. The machine marks was the culprit. Also, some do it where the end plate mates to the main housing. I have a surface ground plate I use with wet-or-dry sand paper in the parts washer for sanding piston tops to correct the deck. I started lapping the oil pump mount, end of the housing, end plate, and pull the dowel pins from the rear main cap. I lap all the machine marks from those four surfaces. Stopped the leakage. I prefer my oil going into the oil galley. I don't see how excessive leakage those two places could help anything. Some machine marks are worse than others. Hope this gives somebody something to look at.

[Ron Gusack]

Originally Posted by Ed Wright

Ron, from what I saw with the local circle track cars, I would say you are mistaken. I posted what I observed. More power required to run the big pump is the only thing I know of that would wear gears like that. Old as I am, I haven't seen everything yet.

From your description of the oil pressure you are seeing, I would say you problems other than the pumps. I just put a new Moroso std volume pump in my spare engine, which I recently sold. Oil pressure was solid at 60 psi all the time. Hot or cold (5W20) idle or WOT. You have something wrong somewhere.

I have an old rear main cap, with a gauge on it. I bolt my pumps on it, drop it in my parts washer, and spin it with a 1/2" drill to see where the relief valve is set. Whatever it shows there, is what it shows in the car. My thinking is solvent, being thin, would be similar to hot, thin weight oil.
I noticed solvent spraying out from the area where the pump mounts. The machine marks was the culprit. Also, some do it where the end plate mates to the main housing. I have a surface ground plate I use with wet-or-dry sand paper in the parts washer for sanding piston tops to correct the deck. I started lapping the oil pump mount, end of the housing, end plate, and pull the dowel pins from the rear main cap. I lap all the machine marks from those four surfaces. Stopped the leakage. I prefer my oil going into the oil galley. I don't see how excessive leakage those two places could help anything. Some machine marks are worse than others. Hope this gives somebody something to look at.

Thanks Ed. The test results I posted was for pumps mounted to a rear cap and in a pan with 46 degree, super thick 10-30 oil. I like the idea of using the parts washer fluid to closer replicate hot oil and I would not have thought of that. I have thought about the various mating surfaces leaking, but didn't really know a good way to fix the problem. Do the pins just pull out of the rear main and press back in? Could I use a piece of glass to wet sand on?

[Ed Wright]

Originally Posted by Ron Gusack

Thanks Ed. The test results I posted was for pumps mounted to a rear cap and in a pan with 46 degree, super thick 10-30 oil. I like the idea of using the parts washer fluid to closer replicate hot oil and I would not have thought of that. I have thought about the various mating surfaces leaking, but didn't really know a good way to fix the problem. Do the pins just pull out of the rear main and press back in? Could I use a piece of glass to wet sand on?

They make a slid hammer style tool for pulling dowel pins. Snap-On makes one.
The dowel pins do go back in. Never used glass. May be fine. I used 280 grit paper, then 400.
I think you have something screwy going on to have oil pressure like you discribed. I've never had one do that.

[Dwight Southerland]

Originally Posted by Ed Wright

I think you have something screwy going on to have oil pressure like you discribed. I've never had one do that.

You need to look at the block carefully. You could have an internal crack in an oil gallery that expands with heat. I have seen that on two big blocks that exhibited similar characteristics. It can make you crazy chasing pumps, pickups to solve the problem.

[Ron Gusack]

Originally Posted by Dwight Southerland

You need to look at the block carefully. You could have an internal crack in an oil gallery that expands with heat. I have seen that on two big blocks that exhibited similar characteristics. It can make you crazy chasing pumps, pickups to solve the problem.

Just to be clear, the pressure fluctuation was on this test apparatus not in the car's engine.
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[Ron Gusack]

Originally Posted by Ed Wright

Ron, from what I saw with the local circle track cars, I would say you are mistaken. I posted what I observed. More power required to run the big pump is the only thing I know of that would wear gears like that. Old as I am, I haven't seen everything yet.

From your description of the oil pressure you are seeing, I would say you problems other than the pumps. I just put a new Moroso std volume pump in my spare engine, which I recently sold. Oil pressure was solid at 60 psi all the time. Hot or cold (5W20) idle or WOT. You have something wrong somewhere.

I have an old rear main cap, with a gauge on it. I bolt my pumps on it, drop it in my parts washer, and spin it with a 1/2" drill to see where the relief valve is set. Whatever it shows there, is what it shows in the car. My thinking is solvent, being thin, would be similar to hot, thin weight oil.
I noticed solvent spraying out from the area where the pump mounts. The machine marks was the culprit. Also, some do it where the end plate mates to the main housing. I have a surface ground plate I use with wet-or-dry sand paper in the parts washer for sanding piston tops to correct the deck. I started lapping the oil pump mount, end of the housing, end plate, and pull the dowel pins from the rear main cap. I lap all the machine marks from those four surfaces. Stopped the leakage. I prefer my oil going into the oil galley. I don't see how excessive leakage those two places could help anything. Some machine marks are worse than others. Hope this gives somebody something to look at.

So you tap the rear main cap that's actually going on the race engine? How else could you determine that there was a mating surface leak. Do you leave the threads in the cap when it goes on the race motor?

[Ed Wright]

Originally Posted by Ron Gusack

So you tap the rear main cap that's actually going on the race engine? How else could you determine that there was a mating surface leak. Do you leave the threads in the cap when it goes on the race motor?

Ron, I think I said I used an old main cap. If I had a piece of aluminium plate on hand at the time, I would have made a test fixture from that. The cap is tapped for a pipe thread, with a hose and oil pressure gauge screwed into the oil passage. It ain't purty, jut a quickie with what I could find at the time, about twenty years ago. Works, so I still use it. I just don't get it out and show it off. :-)

I am not a professional engine builder. I just cobble my own crap together, and have helpped a couple of other guys in the past. Someone like Adger differs, I defer to them.

[Ron Gusack]

Originally Posted by Ed Wright

Ron, I think I said I used an old main cap. If I had a piece of aluminium plate on hand at the time, I would have made a test fixture from that. The cap is tapped for a pipe thread, with a hose and oil pressure gauge screwed into the oil passage. It ain't purty, jut a quickie with what I could find at the time, about twenty years ago. Works, so I still use it. I just don't get it out and show it off. :-)

I am not a professional engine builder. I just cobble my own crap together, and have helpped a couple of other guys in the past. Someone like Adger differs, I defer to them.

You've certainly helped me a ton over the years. I appreciate the guys that help us littles and I understand those that don't want to share info. You did say "old cap", but I thought you found fitment issues with your race stuff that you found by testing the race stuff. Here are pics of the cap I modified. I'll try to test tomorrow. I was thinking about using ATF for test fluid. What do you think?