What pump do I need?

[CaliTrav]

Hi all,

In the process of rebuilding an A series. Discovering a few things in the process, the latest of which seems to be that the 1098 block has been given a 1275 cam.

In case the photo upload doesn't work the drive is given by the 3 pointed insert with a vertical bar. I assumed that the standard pin drive pump would work, but this pushed the cam out by about half an inch because the driveshaft on the pump was too long. That's what led me to figure it's a 1275 cam.

However when looking for 1275 pumps, they're all spade drive - needing a slotted cam - or star drive, needing a different 3 pointed drive piece and the corresponding star drive pump.

What I can't seem to find is a short driveshaft version of the pin drive pump - is there such a thing, or has it just been superceded now?

[philthehill]

Have you one of these fitted?
https://www.ebay.co.uk/itm/Classic-Mini ... SwyjBW4I9A

If not - what you need is the star drive oil pump with star drive adapter and the spacer plate between oil pump and block.
Here is a 1275cc camshaft with star/spider drive adapter:-
https://www.ebay.co.uk/itm/185236300561 ... SwJoZhzZxe
This is the oil pump:_
http://www.minispares.com/product/Class ... o%20search
This is the spacer:-
https://www.somerfordmini.co.uk/spacer- ... 1098-block

This is the small block pin drive oil pump suitable for the standard 1098cc engine.
http://www.minispares.com/product/Class ... o%20search
To be honest there is little difference in cam timing between the 1275cc engine and the 1098cc engine. It may be easier to go back to standard 1098cc spec and fit the pin drive oil pump and 1098cc standard pin drive camshaft.
The bonus with the 1275cc cam is the 1/2" width cam lobes which reduces wear.
Always fit new cam followers even if using the original camshaft.
You can fit new cam followers to a S/H camshaft but you should not fit S/H cam followers to a new camshaft or existing camshaft.
Make sure that your oil pump rotor is keyed to the drive shaft. If not - on a cold morning the drive shaft can rotate in the rotor due to the thickness of the engine oil. I have in the past exchanged drive shafts to overcome the shaft length differences and the difference in drive - but unless you have a selection of oil pumps finding the right drive shaft is not always possible. Here is a pin drive oil pump to which I have changed the drive shaft.

Oil pump 1.JPG (235.42 KiB) Viewed 466 times

Happy New Year to you and all those reading this.
Phil

[CaliTrav]

Thanks Phil,

I have fitted the reverse of that first link - so a bar in the middle and space either side for a pin drive.

However that first link with the right pump would also solve the issue.

I think that because it's a 1275 head and the block has been pocketed in the past, the 1275 cam is a slightly lower lift Vs the 1098? Not sure though. It could just be a wear thing as you said, or just whatever was nearest part to hand whenever whoever it was built it last time!

Happy new year all.

[philthehill]

You seem to have more of a selection of oil pump adapters your side of the pond. I tend to just mix and match the pump drive shafts.

As regards valve lift the 1098cc is 0.312"/0.312"...with standard rockers.
....................................1275cc is 0.318"/0.318"...with standard rockers.

The inlet/exhaust periods below are for standard camshafts:-

The 1098cc inlet opens 5 degrees BTDC - closes 45 degrees ABDC.
..................exhaust opens 51 degrees BBDC - closes 21 degrees ATDC.

The 1275cc inlet opens 5 degrees BTDC - closes 45 degrees ABDC.
..................exhaust opens 51 degrees BBDC - closes 21 degrees ATDC.