SRM Replacement Oil Pump

[A10 JWO]

My 1954 still wet sumped after fitting the new pump from SRM, BUT I am pleased I bought it; quality : )

[chaterlea25]

Hi All,
There are several leakage paths that cause wet sumping on A10's

Did ask SRM about wet sumping they said it still would the pump would not correct it,
They told me the truth impressed,

A new pump will only solve some of the leakage path's
1, through the pump drive spindle and porosity /leakage between the pump parts,
2, through the pump gears and into the oil feed system when the anti sumping anti drain ball does not seal as it should
No 2  can be resolved by either an engine strip or modifying to the A65 position of placing the ball against the rear delivery port of the pump

It takes some extra work and £$€'s to reduce the wet sumping to minimal levels 
But worthwhile in my opinion

John

[RichardL]

2, through the pump gears and into the oil feed system when the anti sumping anti drain ball does not seal as it should
No 2  can be resolved by either an engine strip or modifying to the A65 position of placing the ball against the rear delivery port of the pump

It takes some extra work and £$€'s to reduce the wet sumping to minimal levels 
But worthwhile in my opinion

John

John,

Is it fair to say that changing to the A65 ball.arrangement doesn't automatically solve wet sumping due to ball seat, but makes it easier to create and maintain a good seat? Last time my cases were apart I created a tool with a ball glued to the end of an aluminum tube and used that with valve lapping compound to create a good seat for a new ball. Has held well, so far. Ahh, just realized I am going to get heat for introducing grit to the oilways, but I am pretty certain my tediuos washout efforts were successful.

Richard L.

Richard L.

[muskrat]

G'day Richard.
My thoughts on your method. Even with your impeccable cleaning there is a chance of lapping compound particles being embedded in the aluminum seat. This would wear the ball and create minute high spots in the seat.
My method is to buy two balls and use one to repair the seat. Pop it in the hole and give it a light tap with a pin punch and hammer. Throw that ball away and use the other. 7 years since I did the cafe, she might wet sump about 1/4 cup in a month (not that she goes unused that long). I did rebuild my original pump at the same time.
Cheers   

[chaterlea25]

Hi Richard

Is it fair to say that changing to the A65 ball.arrangement doesn't automatically solve wet sumping due to ball seat, but makes it easier to create and maintain a good seat

Probably

Lapping or tapping the ball into the seat widens the contact area, so the spring pressure per sq mm. drops in proportion

The issue with the A65 arrangement is preventing the gasket from interfering with  the ball seating
It took m a couple of attempts and a home cut gasket to sort it

John

[JulianS]

For alloy bodied A65 pumps BSA recommended tapping the ball onto the seat  to get a good seal. For A65 ball/spring assembly.

I did not need to do that with my SRM pump.

Best pump gasket to use is the SRM type which has the holes in the right places and holes the correct size and which extends to the front mounting stud. Avoid the gaskets with tiny holes.

Photo shows the SRM gasket left, a new old stock A10 one at top right and a nasty cheap pattern one at the bottom right.

[chaterlea25]

Hi Julian and All,
The SRM gasket was not available when I built my SR and other A10's so I cut my own,
I make sure they are a tight fit on the stud holes so they cannot move in relation to the the oil delivery hole (especially)
I have another A10 engine to do soon so I may try the SRM gasket

John

[worntorn]

Is there a specification for pump outputs, for example  return flow rate at idle or some other Rpm with a new stock pump and also the SRM pump?

Glen