11 replies to this topic

[les]

Hi guys can anyone tell me of any obvious differences between a mk3 cooper s block and a standard 1275 block. Is there a reference book to help identify cooper s parts from standard parts or part numbers to help.

cheers les

[bmcecosse]

If you mean the very last of the S blocks - then NO difference - except should have been drilled/tapped to take the extra stud and the special bolt for holding down the head! The REAL Cooper S blocks of course have removeable cam follower covers.

[Asphalt]

MkIII S would've tapped chest covers and a AEG312 number. 'Normal' 1275cc blocks have no covers and a 12A1279 number (or very early thin flange Austin 1300 ('66-'67) blocks witch have a 12G949 number). To my knowledge there is no such thing like a solid-wall 'S' block (maybe as a pretty late manufactured replacement engine - but not original).

Rover Cooper block has a WFM1024 number on the front and a 3/8" UNF oil pipe thread. Later injection blocks ('92 onwards) have are differently threaded. Metro engines (at leasat the early ones!) have no number on the front side.

[bmcecosse]

The last of the S models had a solid wall block - still supposedly with an EN40B crank - although there is some doubt about that too!

[Sherlock]

The Mk3 'S' block was certainly solid, devoid of tappet chest covers, I used to have one, (the block, not the whole car) & I was frequently told the EN40B crank had actually disappeared well before the Mk3 'S' ceased production.

[Cooperman]

The early Mk 3 'S's had the cam chest covers and the EN40B crank with the 1.625" dia big-ends. No-one seems to be sure when they ran out of genuine 'S' blocks and went to the 1275 GT block, but the cranks in the solid blocks definately were never made from EN40B and they had 1.75" big-ends. However they did have 11-stud (well, 10 stud & 1 bolt) heads, twin 1.5" SU's and a better dcam. That identical 1300 engine was carried on with the Innocenti Mini-Cooper 1300 until 1975 and having just finished re-building an original Innocenti 1300 engine from a 1973 car I can confirm that the crank is not EN40B. There never was an ex-factory EN40B crank with 1.75" big-ends.

[bmcecosse]

It didn't have the large big-ends(!) - but I'm fairly sure that - for a while - the EN40B crank - with small big-ends and proper AEG 177 S rods - was fitted to the solid block. Anyway - point is - the block is no different, except for extra stud/bolt holes - which are easily 'faked' into any block. However - most when doing this go for two extra studs - which is a bit of a give-away!

[Guess-Works.com]

Heritage have all the information on Cooper S blocks...

The engine number is usually the key, but without that could be anything if it's a solid wall...

[62S]

If you mean the very last of the S blocks - then NO difference

Wrong

The last of the S models had a solid wall block - still supposedly with an EN40B crank

Wrong

The Mk3 'S' block was certainly solid, devoid of tappet chest covers

Wrong

Anyway - point is - the block is no different, except for extra stud/bolt holes

Wrong

Despite the claims above, all genuine Mk 3 S blocks have tappet chest covers on the back.

Later ones have two numbers cast in them, namely AEG 312 and AEG 634.

Very, very few Mk 3 S's had an EN40B crank from the factory as very, very few 12G 1505 cranks were made in EN40B.

Don't give out incorrect advice - if you don't know the answer, don't post!

[62S]

There is one other major difference I forgot to mention, about £500.

[bmcecosse]

No - the last run of Cooper S engines very definitely DID have the solid block - no cam follower covers - and some DID have EN40B cranks - with the small big-ends - not the BIG big-ends! My mate had one - at the time - so the block facts are correct - the crank detail is from journals etc at the time. We never opened it up!

"Don't give out incorrect advice - if YOU don't know the answer, don't post!"

Edited by bmcecosse, 17 November 2009 - 10:05 PM.

[62S]

You are wrong. You're just typing rubbish, man.