I am in the process of assembling my Mk2 engine. I fitted a new oil pump from MKOL, but it is mounted by 2 studs, whereas the original Hoburn Eaton pump is mounted with 4 studs. When the engine was running some years ago, it had good oil pressure. The workshop manual states that the Hoburn Eaton pump can be dismantled and refaced if clearances are excessive. What do the experts out there think.
I am leaning towards fitting the original pump.

2 studs should be fine

Should be bolts not studs that secure the oil pump to the block.

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Steve

Correct, they are 1/4" bolts.

The Hoborn-Eaton pumps with the alloy body are prone to wear due to the unfiltered oil supply via the gearbox, as I guess everybody knows.
Once the concentric ring and body are scored, I cannot see how it can be usefully repaired.
For me, its a throw-away item given their new price ($50-$90).
Having said that, Karcraft list the part AEG410 at $341.77 retail, which I think is the Mk1 three-bolt item. Can anyone confirm this is correct?

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

If fitting a new 2 bolt pump ensure it has a good chamfer on the corner that goes into the block. If not the gasket can leak.
Re the aeg410 pump this is the 3 bolt pin drive one used on mk1 and early mk2S. If your old pump had 4 bolts it's the later S & GT spider drive pump. The 2 bolt pump replaces these and works fine.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks for the info Doc. Yes it is a spider drive. My engine is a '69 Mk2, so the cam must have been changed at some time. Probably when the engine was bored & head modified. It is not a lumpy cam though.

Don't know what i was thinking definitely bolts as corrected

Rechecked the fittment of the 2 bolt pump, has no chamfer, but fits well in the block cavity.
Thanks again for all the advice.

I would chamfer it. I had a motor here which refused to get ANY oil pressure until I did this. Even with a thicker custom gasket. With the pump primed.
Original pumps all had a good chamfer to clear any radius in the corner of the block recess.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.