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Hello all , I'm just trying to source a replacement oil pump for the slot drive cam shaft from Mini Spares . All my spare pumps are spline drive with 4 holes in the body . I note the block (thin flange) only has 3 threaded holes to attach the pump body so a 4th hole has to be drilled and tapped in the block but to what depth ?

Just spoke to Somerford and Mini Spares and apart form their pumps being expensive they say the block has to be drilled to accept the new pump bolt holes .

Why can't I machine a spade on my spare oil pump drive shaft , thus removing the spline , to fit the cam slot drive ?. Has it been done before ?

Thought about fitting a new pump shaft but its interference fit (no cross pin) with the pump rotor.

Any comments would be helpful

If you need a Slot Drive Oil Pump, why not just fit a complete 1275 Slot Drive Pump? I've found the steel backed ones are great, I only looked at mine the other days, it's done 40 000 km and shows no wear or scoring of any note. Just to check with the Pump Drive that's on your cam, the original S type was a Pin Drive and the newer cams these days all seem to be Slot Drive.

It will only be 1 hole you'll need to drill and tap, just measure the depth of the other hole at the top of where the pump mounts and drill to that depth. I'd suggest drilling this in a drill press to get it square and even start taping it in the drill press, only turn the chuck by hand. Thread is 1/4" UNF.

Hi thanks for your reply

Recommend to loctite some grub screws into the unused holes, as the drilling goes through to the gallery.

Also, if you fit up the new pump using the one bolt that aligns, then you can scribe/center punch through the other bolt hole.

Easy enough job with a steady hand to then drill and tap the extra hole for the two bolt pump.