9 replies to this topic

[1963MKI]

I have an Austin 1300gt engine (mk3 cooper s type roughly), I have a modern Cam as an upgrade which is slot drive what are my options for an oil pump?

[nicklouse]

Fit a slot drive pump.

[1963MKI]

Yes, just wondering are there any that I can fit without modifying the block to fit an a-plus pump.

[imack]

I'm certain a slot drive (A+) pump is a straight swap for an older spider drive, just uses 2 bolt fixing rather than 4 bolt.

[imack]

A+ slot drive pump in a late pre A+ block - no modification required.

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[Cooperman]

There are 3 types of oil pump fittings. A 2-bolt, 3-bolt & 4-bolt.

I had a problem with a new standard 2-bolt pump recently as although brand new, it would not give any oil pressure. I took the engine out and fitted a Metro-Turbo type pump GLP110MS from Mini Spares. That is a 2-bolt pump and as soon as I had put theengine back in, it gave 65 psi on the starter motor with the plugs out. 

The one which didn't work was a GLP138.

If your block is drilled and tapped for a 4-bolt pump, make sure that the two unused holes, when fitting a 2-bolt, have broken through into the water jacket. This is normally only a problem with the genuine 'S' blocks, but if in doubt, plug the redundant holes with a 1/4" UNF stud.  I had an engine with a new 2-bolt pump on a Cooper 'S' and the water jacked had been broken into by the taping for the 4th olt and water got past the oil pump gasket into the cooling system.

I doubt that this will be a problem for you as it is probably only an issue with the early 3-bolt drilling blocks which have had the 4th hole drilled and tapped subsequently, but it's worth a quick check.

[Spider]

If your pump is 3 bolt fixing, you'll need to drill and tap (1/4" UNF) one hole if changing to a spade drive pump.

[Cooperman]

If your pump is 3 bolt fixing, you'll need to drill and tap (1/4" UNF) one hole if changing to a spade drive pump.

 

That was where I had the problem. I had a Mk.1 'S' block and wanted to fit a 4-bolt pump, so I drilled and tapped for the 4th hole.

All was fine until I did another engine rebuild some time later and used a 2-bolt pump as the 4-bolt were out of stock.

The 4th hole, which was now redundant, had just broken through into the water jacket and whilst this was not a problem with the 4-bolt pump, with a 2-bolt the gasket land between the pressurised oil and the water was about 2 mm. It broke through and pumped loads of oil into the coolant. The problem was hard to find and all the pundits told me I had a cracked block, etc. Finally someone told me that he knew of someone who had the same issue, again with  genuine 'S' block. 

I plugged the hole, which is still plugged, with a 1/4" unf stud which has a slot so that I can always take it out and fit a 4-bolt pump should I want to, and the problem was solved. The messy bit was flushing the entire cooling system which was full of brown sludge!

I don't think later blocks have the same problem when drilled to the same depth as the other holes.

[Spider]

 

If your pump is 3 bolt fixing, you'll need to drill and tap (1/4" UNF) one hole if changing to a spade drive pump.

 

That was where I had the problem. I had a Mk.1 'S' block and wanted to fit a 4-bolt pump, so I drilled and tapped for the 4th hole.

All was fine until I did another engine rebuild some time later and used a 2-bolt pump as the 4-bolt were out of stock.

The 4th hole, which was now redundant, had just broken through into the water jacket and whilst this was not a problem with the 4-bolt pump, with a 2-bolt the gasket land between the pressurised oil and the water was about 2 mm. It broke through and pumped loads of oil into the coolant. The problem was hard to find and all the pundits told me I had a cracked block, etc. Finally someone told me that he knew of someone who had the same issue, again with  genuine 'S' block. 

I plugged the hole, which is still plugged, with a 1/4" unf stud which has a slot so that I can always take it out and fit a 4-bolt pump should I want to, and the problem was solved. The messy bit was flushing the entire cooling system which was full of brown sludge!

I don't think later blocks have the same problem when drilled to the same depth as the other holes.

 

 

Fair call Peter. I've done quite a few (including some S Blocks) and haven't had this issue, but I can see for sure how it can occur. I'd say that's more of an issue with the S Blocks, the garden variety 1275 Blocks seem to have plenty of meat here as they use the same casting on Manuals as they do Autos. The Machining here for the Auto Pumps is 1/4" deeper than the Manuals, and even then, drilling and tapping them I've not - yet - broken in to the cooling jacket. In regards to the S Blocks, they do likely have less meat here as they never did them in an Auto version and making the cooling jackets that much bigger, especially at that end of the block, isn't a bad thing at all.

[Cooperman]

Yes, I think that it is the original S blocks which potentially have that problem. Before I drilled and tapped mine for the 4th hole I measured the depth of the other 3.
However, I just broke through into the water jacket.
It sure took some work to find the reason for a cooling system full of brown oily gunge!