Modifying oil pump.

You cant increase the flow of the A pump just by opening up the holes or reducing the shaft diameter.
If you could we would only need one size of pumps, but with different size holes
Lawrie
 
on an original engine. i am wondering why the need to modify the pump for higher flow? if the original pump with the narrower shaft is use it will fill/overfill the oil gallery which is all that is needed to oil the engine. this is why there is a oil drainback tube to take care of excess oil.
on a pressure fed engine different story.

i am wonder why the need? i see lots of discussion on oil pumps.
 
For grins and giggles I built a test fixture and tested three pump configurations. At 660 rpm i measured the time it took to pump 1 gallon of 15/30 oil at room temp; I obtained the following results:
Stock Model A Pump with 1/2” shaft - 84 seconds
Model A Pump with shaft turned to 3/8 dia - 60 seconds
59a V8 Pump modified for Model A - 38 seconds.

Albeit I’m not a NASA sanctioned test facility I resolved the debate in my mind as to the direction I was following. The pressure produced by either pump is quite worthy, the v8 pump can be easily regulated to 30 pounds. A thanks to Jim Brierley for the wealth of information in his book and taking time to answer my questions.
 
No problem for a stock Model A but this thread started as a question of
modifying a stock oil pump for use in the new Burtz engine.
 
You cant increase the flow of the A pump just by opening up the holes or reducing the shaft diameter.
If you could we would only need one size of pumps, but with different size holes
Lawrie

Stock Model A oil pumps have a small inlet window to the gears. When the intake window is enlarged to expose more gear area, the output volume increases. Larger passages have nothing to do with volume, but they will provide less friction.




on an original engine. i am wondering why the need to modify the pump for higher flow? if the original pump with the narrower shaft is use it will fill/overfill the oil gallery which is all that is needed to oil the engine. this is why there is a oil drainback tube to take care of excess oil.
on a pressure fed engine different story.

i am wonder why the need? i see lots of discussion on oil pumps.
__________________
old ugly

but for a stock engine they must supply enough oil

or is there a problem?
__________________
old ugly

A stock Model A engine does not need a modified oil pump.
People posting on this thread are not discussing a stock Model A engine.
 
I was taught a few things years ago I would like to throw out here and see what you think. The study of fluid flow in physics, or hydro dynamics, has some basic rules when a positive placement pump is used. The volume of the fluid flow is determined by rpm and is fixed. You can change the speed of the flow, and the fluid pressure, by the size of the openings it flows through. A small opening and the fluid flows faster to maintain the fixed volume. A wider opening will cause the fluid to flow slower. Think of a river, the volume is the river is the same even though it goes faster where the river is narrow and slower where it is wider, but the gallons per minute remains the same. The gear pump delivers a constant volume because it is a positive displacement pump and fluids are not compressable. By changing the openings in the pump you are changing the speed of flow and the pressure but not the total volume. If you want more volume you need to speed up the pump or get a pump with biggger gears. My two cents.
 
Chris Haynes said:
I have read the instructions on how to increase the flow of a stock oil pump. I am limited of doing this myself because I don't have a milling machine. Is there anyone who does the work on these pumps?
Click to expand...

Bob C said:
No problem for a stock Model A but this thread started as a question of
modifying a stock oil pump for use in the new Burtz engine.
Click to expand...



i don't see a Burtz engine being mentioned here by the OP.

is he building a pressured oiling system? i guess i am not reading between the lines.
 
Russ/40 said:
Not shure, but I suspect Chris is trying to perform the modification recommended for use in the new Burtz block for pressurizing the oil flow to all bearing surfaces, thus the desire for more flow.

I too, would like to make that modification with hand tools if someone has proved it can be safely executed
Click to expand...

I spoke with Specialty Motor Cams this morning. There is a lighter spring that can be inserted in place of the internal "green" spring that will reduce oil pressure from a max of 50psi to approximate 8psi at idle and 18psi at 2200rpm: McMaster-Carr spring #9657K153. This is a 2" compression spring with a .313OD. Cost for a pk of 12 is $9.31. Much cheaper and easier to install than a pressure relief valve -- and for those ordering a Stipe pump for your Burtz engine, request the lighter spring for lower pressure, and this is what they will install in their oil pump.
 
If anyone is using the oil pump from Specialty Motor Cams and want to reduce the pressure by installing a lighter spring for the pressure relief valve, I have a bunch and will send you one, no charge. I bought some from McMaster Carr on advice from Stripe Machine Company. The minimum order is 12. I will use one and maybe one for a spare. The part number from McMaster Carr is 9657K153, Compression Spring 2" long by 0.313 OD. If you want one send me a PM with your mailing address.
 
You must log in or register to reply here.
Back
Top