OIL PUMP PRESSURE

[CarMan35]

Has anyone out there ever determined the actual flow rate and pressure created by the 1500 oil pump, before regulation? Has anyone seen the specifications for the pump's output in writing in a factory manual?
Thanks,
John Slusar

[mikeyr]

I have never seen anything beyond 30psi at 30MPH, I can peg my gauge when the motor is cold but not after it warms up, as expected.

Sorry, I know you asked about flow, that pressure is the only thing I have ever read about it...others can chime in anytime with more info

[CarMan35]

Just before the oil flows into the gallery, it hits a pressure setting relief valve, controlled by a spring. That valve limits the pressure of the oil that enters the gallery on its way to the bearings, etc. It is correctly set when the thinned-out hot oil leaves a residual pressure (after completing its duties) of 30-35 psi while running at 35 mph in top gear. However, the raw pressure available from the unregulated pump can be much higher. Some pumps, such as those used in flathead Fords, have a built-in pressure limiting relief valve, but there appears to be none in the Singer pump. With this new full-flow oiling system that I am trying to perfect, I need every fact I can collect. I am concerned about this, mainly because factory literature describing a modification to the rocker arms by drilling a hole to spray oil onto the cam lobes, carries a caution that the hole diameters are critical, and will result in a 10psi drop in residual oil pressure. This leads me to think that the delivery rate of the pump may be marginal. Since my full-flow system will not dump oil back to the sump, as in the original bypass design, I should have a surplus of pressure available, which is a great safety factor.

By the way, this project is very do-able, but not as easy as I had been hoping. I have been trying to keep my modifications simple and inexpensive, so that others might do the same to their engines. However, yesterday I made the most compact assembly as possible, using the original internal oil pump tube, but could not make it fit in the tight confines of the engine block. One has to avoid contact with a lot of spinning pieces in there! I have confirmed now that a very carefully bent internal oil tube will need to be made, and custom-fitted...not an easy trick to duplicate.
John Slusar

[Richard Clark]

Hi carman35

Did you get this mod up and running?

Richard

[indian301]

John,
You state below that you will have a surplus of pressure because all of the oil will not be returning to the sump. Whether the oil pan is 1/4 full or overflowing the pressure is going to remain constant as long as the sump is submerged in oil. The way to increase the oil pressure would be first to measures the clearances between the gears and the housing. If they are too loose you could have the gears/ rotor hard chromed to bring them back into specs. The second way would be to experiment with the spring pressures on the relief valve or by decreasing the orifice size in the oil galleys. Drilling too large of a hole to add extra oil to the camshaft will reduce your oil pressure. I would be more worried about the cam bearings not getting enough oil. When I was drag racing we used a dry sump system. This system consists of an external oil pump, belt driven, mounted on the front of the engine. The advantages are very little oil in the oil pan; this would be good for road racing where the oil would be sloshing around through the turns. Increased horsepower because the crankshaft is not being sprayed with oil as the RPMs increase and create drag. The pumps are adjustable. We had 8-10 pounds of pressure for every 1,000 rpms, but drag races are only 1/4 mile long. Looking through some of my old automotive books. A 1972 4 cylinder Chevy engine calls for 30-50psi at 2000 RPMs.

Dave V-6 4AD

[CarMan35]

"You state below that you will have a surplus of pressure because all of the oil will not be returning to the sump. Whether the oil pan is 1/4 full or overflowing the pressure is going to remain constant as long as the sump is submerged in oil. " Dave, you missed my point. The factory system had to provide a wasteful direct dump to atmosphere to encourage any oil to flow through the bypass filter. When the oil had a choice of going through tight bearing clearances or directly to the open sump, some of it took the path through the filter. This "hole" in the system has been plugged in my new design, which allows the full pressure potential of the stock pump to be developed. Of course, that is limited by the adjustable relief valve spring, which will dump residual pressure (beyond the spring setting) to the sump.

As you know from my latest post this evening, I decided not to drill the rocker arms to spray oil onto the cam lobes, but resorted to a second auxiliary oiling system, affording direct oil spray onto the lobes. Therefore, the entire potential delivery of the stock engine oil pump, as controlled by the pressure relief valve spring setting, is available for main, rod and cam bearings, with a little splash onto the cam lobes, as per the original factory design, but without the wasted delivery to the bypass return bore. I was able to locate NOS pump gears, and my pump housing showed little wear, so I have a good basic system, but as the pump wears, the elimination of that open bypass filter return to sump will have the effect of keeping additional delivery volume and pressure in reserve.

I had looked into a dry sump system, but I felt that it would not be appropriate in the historic sports car class that my car will be entered. It is more of a high-speed touring class than a true racing class, so my emphasis has been on longevity through improved oiling.

John Slusar

[CarMan35]

Oh, No! I spent nearly an hour describing all aspects of my oiling system modifications, along with the big failure, but it does not appear in this thread. Mikey, was it lost?
John Slusar

[mikeyr]

terrified Mike here...

yes, its lost, now I want to know why and how !

What did you do ? Can you spend another hour and e-mail it to me ? did you put pictures in ? did you do anything odd ?

[CarMan35]

Mike: No photos, just text...lots of it. Just when I gave the Submit command, I noticed a new posting to this thread (Indian301), and I clicked on it to read it. I then answered that post, as a sort of continuation. When I made the second submit command, I noticed that there were two copies of that intermediate posting by Indian 301 displayed, but nothing of my first posting. I refreshed the screen, and saw what you see now...Everything is there, except my first post of the day.

I suspect that my viewing of the Indian 301 post and subsequent reply somehow wiped out my long letter, but I can definitely say that I did not click on Preview when I sent it, and that my long letter was definitely displayed before I clicked on the new Indian 301 posting. I didn't notice, but I am suspicious that the result of my Submit command was actually a Preview, OR I may have clicked on the Edit command when I didn't see my long letter after writing the second reply. Obviously, there was some confusion on my part, and the situation of a second posting by another member in the midst of my submission led me to give an errant command, or one out of sequence. Since my long letter was on the screen when I accessed the Indian301 letter, I must have inadvertently written over it, thus resulting in that double showing of his letter. Unless you are able to somehow view my submitted long letter in its form before I clicked Edit, I guess it is lost in the "bit bucket". Just a dumb and unusual circumstance of timing. I will be more careful in the future, as I must have missed a significant button or option after my long letter submission. As the old saying goes, "When you ASSUME something, you make an ASS out of U, and an ASS out of ME!" John Slusar

[CarMan35]

Okay, here is a second shot at my long letter…
A lot has happened since I made my original post a year ago. My early experiences showed that there was too little space within the engine block to contain all of my tubing, without risking destruction against a spinning crankshaft counterweight. As a result, I came up with a different design. I rebuilt the oil pump with NOS gears. I made an adapter plate that mounted to the original Singer bypass filter mounting pad, on the side of the block. It was designed to hold a remote mount spin-on oil filter adapter, and to take the filter’s output and direct it into the passage leading to the main oil gallery. It also completely blocked off the original passage from the bypass filter to the oil pan, so that the entire delivery was available to the oil gallery. I made a new series of pipes that took the entire oil pump delivery through a hole that I drilled in the side of the block, then into the spin-on filter adapter inlet. This gave me a full flow oiling system with a modern Ford FL1 spin-on filter. The filter incorporates its own bypass, to protect the filter from over-pressurization at start-up with cold, heavy racing oil. I also plugged the original connection from the pump output tube into the oiling system, so that the oil would not simply go back to the sump.

I decided not to modify my rocker arms to spray oil onto the cam lobes, as I wanted to guarantee the full oiling capability for the mains, rods, rockers and cam bearings. I came up with an auxiliary oiling system, supplied by a 12-volt, 1-1/2 gpm pump, with a 65 psi pressure limit. To accommodate this, I modified the Singer oil pan to add a VW Beetle cast finned aluminum racing sump, which adds an extra 1-1/2 quarts of oil capacity. I drilled two holes in the side of the original Singer oil pan. The first allows the external connection of a hose to a steel tube that goes down into the screen filter pickup at the bottom of the VW sump. The second allows the external connection of a hose to a second steel tube that dumps oil into the Singer pan, below the baffle plate.

The valve cover has been modified by the addition of a full-length copper tube having eight “fingers” with aimable brass nozzles, each pointed directly at the eight cam lobes. These nozzles are calibrated to deliver just under one quart of oil per minute, at 140 degrees F. To guarantee this flow rate, I installed an engine block heater (110 volt) made for the Canadian market, which fits the bottom of a VW sump. For my purpose, the engine oil is heated to 140 degrees before the pump is turned on and the engine started.

I also installed a second spin-on oil filter to the right side of the block. The system has been tested to prove that continuous use of the electric pump never steals a drop of oil from the main sump, as the new sump, the associated hoses and the extra filter increase the total oil capacity by an additional 2-1/2 quarts. The combination of the under one quart per minute flow rate plus the spent oil in the head and its quick return to the main sump never approaches the extra capacity available.

The electric pump draws oil from the VW sump, then runs it to a volume/pressure control valve, then on to the valve cover oiling manifold. The manifold “strips off” one quart of oil, then sends the excess flow down to the second oil filter, then directly back to the sump. So, the second system re-filters and cools 5 quarts per minute, as well as affording continuous oiling directly to the cam lobes and rocker arm pads.

Now, for the bad news…the engine is still not running. Faced with high pricing for unknown-source stock pistons from England, I decided to have custom forged aluminum pistons of modern design made for my engine, at nearly the same price. They do not have full cylindrical skirts like the originals, and are of the “slipper” design, for less weight, and have modern rings. Pin placement upped the compression ratio by a point above the stock single carb engine specs. I am using a dual carb head and my own tubular intake and exhaust manifolds, with HS4 SU side draft carbs, as used on the early MGB, and similar to those used on the HRG 1500 cars.

Sounds good, but that’s only on paper. After installation, I determined that the short pistons would have a real problem in the Singer block. To accommodate piston pin installation, the Singer cylinder bores are notched at their bottoms, so that the big ends of the rods can be pushed up into them. This created a conflict with the slipper pistons, as the notches left only 5/8-inch high full bore support for the new pistons when at the bottom of their stroke. I realized that this would result in piston rock and would lead to premature wear and piston slap. In fact, a look at used original pistons will show the scars of the slots, as even they will rock somewhat. So, we decided to fit sleeves without notches to all four bores. This lead to the big problem.

When the sleeves were pressed into the bores, the outward pressure compromised the strength of the engine block transverse bulkheads between cylinder pairs 1-2 and 3-4. Everything is tight there, and water jacket openings run from the block to the head between the centers of the bores and the head bolt securing threads. When the heads were torqued down, the upward pull caused cracks in the block deck, between the water openings and the sleeves, and an actual eruption of the deck allowed a direct leak under the head gasket, into the cylinder bores. We are currently attempting to repair the weakened areas by installing pipe plugs that obscure the cracks and beef up the entire area, but admit a probable 50-50 chance of success.

If that does not work, I will be faced with the daunting task of finding another perfect block, which will be assembled using original full-skirt cylindrical pistons and stock bores with slots. I will install my new oiling systems, so the only net loss will be the modern pistons and rings. All other changes are bolt-ons to the block.

So, that is the good, bad and ugly of this long journey.

John Slusar