oil pump fouling 948cc engine

[TStanb]

Hi,
I have bought and fitted a new (slot-drive) oil pump but it is fouling on the block/gearbox backplate.
Is it OK (or indeed normal?) to relieve the pump so that the backplate fits on properly?
The backplate has MOWOG stamped into the oil pump cover...is this correct?
Thanks.

[pgp001]

I am guessing you have a "Mini" specification pump. I had exactly the same problem when I did my rebuild a few months ago.
I ended up buying the correct pump for a Minor and now have a perfectly good Mini pump going spare.

viewtopic.php?f=4&t=72047

Phil P

[philthehill]

You mention a slot drive. The correct drive for a Minor oil pump is a pin drive. The pin drive has a pin inserted through the rear of the camshaft and the oil pump drive is in the form of a yoke which fits either side of the camshaft pin.
A slot drive is where the camshaft has a slot in its rear face and the oil pump drive fits into the slot.
If you have a slot drive you must have have changed the camshaft to a later item.
The oil pump drive must suit the camshaft drive.
There are three types of oil pump drive:-
1. Pin drive as per original Minor oil pump drive.
2. Star/spider drive which is an intermediary coupling which has a splined drive in its centre into which the pump drive fits and lugs on the outside which mate into the end of the camshaft.
3. Slot drive as described above.

The pump listed below is suitable for fitting to a Minor
https://www.morrisminorspares.com/engin ... it-p830266

The pump listed below is also suitable for fitting to a Minor but may require additional bolt holes drilling in the block.
http://www.minispares.com/product/Class ... o%20search

[TStanb]

Thanks to you two.
Yes I fitted a female slot-drive EVO001 camshaft in my 948 motor so bought the correct (male slot drive) Mini pump to go with it. The question now is, is there a suitable and specific Morris Minor slot drive (male) pump available?
If there isn't I am going to have to think of something else, along the lines of machining the oil pump cover and backplate if necessary

[philthehill]

There is not to my knowledge a specific slot drive oil pump for the Minor.
Here are a few things you can do to make the slot drive pump fit.
1. Change the drive shaft to suit both the rotor and camshaft. This is easy providing you have a selection of oil pumps. I have done this on several occasions. There are long and short drive shafts. Some have woodruff key fitment for rotor location (my preference).
2. Reduce the thickness of the side bosses on the oil pump. I have recently removed a unbranded later bodied type pin drive oil pump from a small block 'A' Series that has had this done to allow fitment (See link below). The overall height (from front face of the pump body to top of boss) of the pump body fully assembled is 35.6mm
3. Reduce the depth of the pump by reducing the height of the centre boss. I had to do this to fit the Cooper 'S' pump.
4. Dome the oil pump cover. Make sure that you have sufficient clearance between oil pump cover and flywheel.
5. There is a spacer that can be fitted between pump and block to compensate for the difference in oil pump drive shafts but should not be needed if you have the short oil pump drive shaft fitted.

The rear engine plate and oil pump cover were not modified to allow fitment of the pump.
This is the same type and style of oil pump body fitted and which had the side bosses reduced.
https://www.ebay.co.uk/itm/CLASSIC-MINI ... Sw7FRWYb3o
The bolt hole boss opposite the cover holding screw did not require to be reduced.

[TStanb]

Yes, my pump is identical to the one in your link. I have already linished a fair bit off all four bosses but I'm sure there is more to have a go at.
I'll start collecting old pumps with a view to building a bespoke one out secondhand parts but I've known folk do this before and it only works if your clearances are totally spot on...half a thou can make a lot of difference to the output, or a seizure if you get it wrong the other way.

I have got a (thicker) 1098 and a (thicker) 1275 backplate but my gearbox is smooth cased with the shorter input shaft so I'm not sure there'd be engaged shaft to reliably transfer the power to the box??

[philthehill]

As your gearbox is smooth cased you need the pressed steel backplate with the soldered in oil pump cover.
The modified oil pump I referred to was fitted to a 948cc engine with pressed steel rear engine plate.
Personally I would not even bother trying to build up an oil pump. Always best to get a new one. The only parts I would swop is the drive shaft to suit the camshaft.
Whilst you have the engine out - fitting the early Triumph Spitfire 9 spring clutch cover (also fitted to the Reliant Kitten) is a useful mod as the cover then gives a bit more grip of the driving/centre plate.
https://www.ebay.co.uk/itm/Triumph-Spit ... Sw-exeoVhD

[TStanb]

STOP PRESS
Have relieved all relevant bosses and a tad off the inside of the cover and the backplate now fits flat, so that's good.