Oil pump cover

[Harryhotrod]

When I had my engine out last, I wanted to replace the oil pump cover, so ordered one but it was bigger any ideas why .

[philthehill]

There are two sizes of oil pump cover.
The 1275cc oil pump cover is larger than the 948/1098cc oil pump cover.
The 803cc and 948cc engines with the thin engine rear plate have the oil pump cover soldered to the rear engine plate to alleviate any possibility of oil leaks between the two.

oil pump cover 1.jpg (51.63 KiB) Viewed 3158 times

The 1275cc oil pump cover is on the right with the raised centre. The 1098cc oil pump cover is on the left. The two covers are not interchangeable.
I doubt that you will find a NOS oil pump cover for a 948cc/1098cc engine but here is a used one being sold on 'e' bay:-
https://www.ebay.co.uk/itm/146305054492 ... R97JuaDUZQ

[Harryhotrod]

Thanks Phil, I know have a 1275 plate so can I just swap this when I pull the motor

[philthehill]

The 1275cc oil pump cover will fit the 1275cc rear engine plate no problem.
The distance and angle from the centre of the crankshaft to the centre of the oil pump is different on the 1275cc to that of the 1098cc oil pump.
The height of the oil pump body can also also effect the ability for the oil pump cover to clear the oil pump body.
All you can do is try it and see if you have sufficient clearance so as not to interfere with the seating and location of the 1275cc oil pump cover when fitted to a 1275cc rear engine plate.
Unfortunately you cannot fit a 1098cc oil pump cover to a 1275cc rear engine plate.
Below is shown the differences between the 1098cc and 1275cc oil pump cover openings in the rear engine plate.
Whilst the difference is not much it is enough to cause problems.