oil pump question? stock 28 motor

[old ugly]

i am using the early style pump housing, i have undercut the new repo pump drive shaft to the same dimensions (0.0408) that the originals were. its ready to go together.

the new pump gears are about .003" longer than the originals that came out.
this means they touch the cap and the pump will not rotate freely.

question,
i see that some suppliers sell a gasket for the bottom plate and am wondering if this is why that gasket is available? and do you folks use this gasket when doing a pump rebuild?

when i take the pumps apart i don't find gaskets in them.

[Synchro909]

I've seen pumps with and without a gasket. My normal procedure is to use a flat surface and a sheet of wet and dry paper and run the pump complete with gears over it till I get a shiny surface on the gear and the pump body. That means the gears just touch the end plate. I expect some would assemble like that but I use a thin piece of paper to make a gasket about 0.0015" thick, just to allow a little clearance for the gears. If the end plate is worn on both sides, I buy a new one.

[Tom Endy]

Attached link may help.

Tom Endy

https://www.santaanitaas.org/wp-cont...-Repair-TE.pdf

[old ugly]

Originally Posted by Tom Endy

Attached link may help.

Tom Endy

https://www.santaanitaas.org/wp-cont...-Repair-TE.pdf

what book is that from? i must have that here somewhere.
thanks
ou

[old ugly]

Originally Posted by Synchro909

I've seen pumps with and without a gasket. My normal procedure is to use a flat surface and a sheet of wet and dry paper and run the pump complete with gears over it till I get a shiny surface on the gear and the pump body. That means the gears just touch the end plate. I expect some would assemble like that but I use a thin piece of paper to make a gasket about 0.0015" thick, just to allow a little clearance for the gears. If the end plate is worn on both sides, I buy a new one.

i worked on that a while now and it is very close. a lot of rubbing.
i have some real thin gasket material i think will work.

i searched to find new style shaft in old style pump body and found no one that sells or undercuts a new shaft for the old pump.
i have undercut on the lathe my new shaft.
do folks just put into the pump the fatter shaft and hope for the best?

thanks
ou

[johnneilson]

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While this will stir up come opinions, here goes.
The end play on the gears itself in relation to the housing and cover are not as critical in this application. The original Model A is just transferring oil at very low pressure if any at all. Leakage around the end of the gear is minimal. If you are trying to pump 50 psi, it may be a little different.

As for the shaft diameter/housing dia. The original housing was a .562~ diameter with a .500 shaft. that equates to .052 sq" area to transfer the oil. equiv to a 1/4" hole.
The service bulletin mentions reducing the shaft diam to increase this area in the original pump housing. Later housings had .625 diameter and the area is greatly increased. approx .110 sq" area. equiv to 3/8" hole. There are other factors such as the length of the housing and the surface finish to affect the actual transfer of the oil.

For example, the pumps I build for the Mod"A/B" are V8 pumps (larger gears) with the integral pressure relief, a billet alum housing into the block with reduced shaft. These are meant to be used in full pressure oiling systems and I limit the pressure to 30 psi.

Best, John

[old ugly]

Originally Posted by johnneilson

While this will stir up come opinions, here goes.
The end play on the gears itself in relation to the housing and cover are not as critical in this application. The original Model A is just transferring oil at very low pressure if any at all. Leakage around the end of the gear is minimal. If you are trying to pump 50 psi, it may be a little different.

As for the shaft diameter/housing dia. The original housing was a .562~ diameter with a .500 shaft. that equates to .052 sq" area to transfer the oil. equiv to a 1/4" hole.
The service bulletin mentions reducing the shaft diam to increase this area in the original pump housing. Later housings had .625 diameter and the area is greatly increased. approx .110 sq" area. equiv to 3/8" hole. There are other factors such as the length of the housing and the surface finish to affect the actual transfer of the oil.

For example, the pumps I build for the Mod"A/B" are V8 pumps (larger gears) with the integral pressure relief, a billet alum housing into the block with reduced shaft. These are meant to be used in full pressure oiling systems and I limit the pressure to 30 psi.

Best, John

so,,, with the new style shaft in the old pump housing there is enough sq " to transfer all the oil needed for the stock gravity fed oiling system which is final fed through a 1/4" tube in the oil gallery? is that correct?

thanks
ou

[johnneilson]

Originally Posted by old ugly

so,,, with the new style shaft in the old pump housing there is enough sq " to transfer all the oil needed for the stock gravity fed oiling system which is final fed through a 1/4" tube in the oil gallery? is that correct?

thanks
ou

The numbers would support that, with the assumption that the housing is not causing a blockage. I would think that if the motor ran for years, it should be fine.

John

[old ugly]

Originally Posted by johnneilson

The numbers would support that, with the assumption that the housing is not causing a blockage. I would think that if the motor ran for years, it should be fine.

John

the engine , i don't think, never saw a lot of use after its last rebuild. the rod bearing/babbit was like new but they are splash. the mains were starting to chip out, #1 piston carved and horizontal groove in the cylinder, the rear main thrust surfaces were excessively worn.

i don't know if any of that was caused from lack of oil. (maybe the rear main damage?). never the less i want to minimize the risk, im checking as much as possible.

thanks
ou

[rotorwrench]

If the pump is assembled with no gasket but still turns freely then it will work with no gasket. If it's making contact between gears & plate and has any resistance at all then the gasket will relieve the bind if it's thick enough. Most available gaskets are pretty thin.

Check for leakage of the plug for for the cross drilling. I recently found one leaking and will have to solder it with silver. Some may be welded but I don't know all the ways that Ford plugged the open end of that feed port.

[old ugly]

Originally Posted by rotorwrench

If the pump is assembled with no gasket but still turns freely then it will work with no gasket. Ir it's making contact between gears & plate a day has any resistance at all then the gasket will relive the bind if it's thick enough. Most available gaskets are pretty thin.

Check for leakage of the plug for for the cross drilling. I recently found one leaking and will have to solder it with silver. Some may be welded but I don't no all the ways that Ford plugged the open end of that feed port.

i have the early oil pump with the soldered on screen cover, its hard to see in there but it looks like my 4 year old grand daughter soldered it accualy both pumps look the same. (crappy looking solder jobs).
i am going to clean it dry it then fill that cavity with gas to see if any wet spots occur. if i get a leak i will have to remove and resolder on the cover.

thank you

[rotorwrench]

Thanks for explaining how those early ones are set up. I've heard of the soldered cover but wasn't sure what all was soldered without looking at one. Some had the clips to hold the cover but I've only seen the photos of those. If it leaks in there it would be difficult to see it with the screen cover on there. The pump I have is one of the late types from a 1931 engine so everything is held by screws. The plug is more like a rivet but it didn't cover the hole. If I shine a bright LED light up into the feed bore I can see the light coming around part of the edge of the plug that is open. A person could also put solvent in the feed hole while holding he pump on an angle toward the plug and see if it leaks out.

[old ugly]

Originally Posted by rotorwrench

Thanks for explaining how those early ones are set up. I've heard of the soldered cover but wasn't sure what all was soldered without looking at one. Some had the clips to hold the cover but I've only seen the photos of those. If it leaks in there it would be difficult to see it with the screen cover on there. The pump I have is one of the late types from a 1931 engine so everything is held by screws. The plug is more like a rivet but it didn't cover the hole. If I shine a bright LED light up into the feed bore I can see the light coming around part of the edge of the plug that is open. A person could also put solvent in the feed hole while holding he pump on an angle toward the plug and see if it leaks out.

thats what im going to try do, fill with gas or gunwash and see if it weeps

[old ugly]

[QUOTE= A person could also put solvent in the feed hole while holding he pump on an angle toward the plug and see if it leaks out.[/QUOTE]

i plugged the top holes turned the pump upside down and filled it with gunwash/lacquer thinner (which will find its way through the tiniest of holes). no leaks at the soldered up cross drilled hole.

i am glad you found this issue.
and i am glad i don't have to try to fix my pump there.

thank you

[rotorwrench]

Having all that soldered stuff would definitely complicate the process. I'm glad to hear it's OK.