mk1-forum.net

Ok ive heard from some people who think they know about minis that some of the last mk3 cooper s s came with a solid block engine.


Is this true??
I always thought that all mini cooper s engine had tappet chests on the back.


If so were these blocks 12g1279 the same as the 1275gt.

Never seen and never heard of an original Mk3 S with a solid wall block. Likewise never heard of a 1275GT with an S engine. BL did merge a few parts at change points but not engines as far as I've ever seen.

Just a tail told by people selling cooper s that have lost there engines

http://www.theminiforum.co.uk/forums/to ... gt-engine/



some people say its true.

Is this a all story!!!!!!

I am doing this from memory so have not put dates to this, but I had a car with a factory replacement Cooper S engine - new, not gold/silver seal.

It was supplied after the Cooper S stopped production. It had removeable tappet chest covers. Based upon that, I can only assume that 'S blocks/engines were readily available throughout production.

migliacars wrote:
Is this a all story!!!!!!

Yep it's cobblers I'm afraid. The only S's with GT blocks were the works race cars. And yes as stated above I've seen quite a few Mk3's with either factory replacement / Goldseal engines fitted early in their lives and they were all S units aswell.

Something like the first 800 Oz 1275GTs had S engines (9FXEY....). Allegedly they dumped the last of them on us before moving on to the "solid" blocks...

Chers, Ian

Here in Aust we had a model called the Clubman GT, this was a very different car to the (UK) 1275 GT, it was in almost every way a MKII Cooper S only in a Clubman shell. There were only around 1200 made from 71 and they finished production in Dec 72, but some of those were stamped 73.

All Cooper S and Clubman GT engines (and transmissions) fitted in production here were fully imported units from the UK.

The early production of the Clubman GT used the Cooper S MKII Engines and still bore the engine prefix numbers as was used on the Cooper S, it would appear that once they were used up, they did continue with the same engine, only with the official engine no. prefix (1200) for a Clubman GT. Although the engines were fully imported, the engine numbers were allocated and stamped (as is required in our local market) locally. I can't recall off the top of my head, but somewhere in 72 they swapped to an engine that was the same spec as the Cooper S (same crank, rods, pistons, head, cam profile etc) only it was fitted in to a solid chest block. These also had a different prefix being 1206. The thrust bearings used were different to accommodate the Cooper S Crank, the Oil Pump was a spider drive type (and so necessitated a change of cam to suit), but in every other way, it was the same as the open chest Cooper S Engines.

I do recall from local factory info that these were in fact late (UK) Cooper S MKIII Engines. We didn't get many here, and I doubt there were many at all made that way.

I have a complete S engine, that was bought new off the local BMC/BL dealer & tuned for a local rally car here in the mid 70ies.

Its not a replacement unit, and the dates confirm, it to be after S production stopped.

The one owner 1971 MK III S we had on display in 2009, also confirmed that = no solid GT block = it had removable tappet covers.

Pete wrote:
The only S's with GT blocks were the works race cars.

The picture of the 8 port CCC car, with solid block in the MCR mag, was older than a 1275GT, so this must have been of a 1300 GT ? or ?

Yes CCC 8 port race cars did use 1300 type blocks in place of cooper s blocks . The 1300 A series solid tappet chest block was first used in MG midgets/sprites in october 1966 . It was also available in some austin/morris 1100,s as a special order at about the same time .
The block used in both of these was a thin flange casting and very weak , most of the early midgets had engine problems , eventually the block was redesigned with a thick flange . BMC also fitted EN 40B cranks in some early midgets to try in get some reliability . The block also gave trouble in the 1100,s , I have seen a few and most have distorted centre main bearing housings .

Downton and Vita must have known about this so would only have used the strengthened block .

I found a little more factory info on the very late MKIII solid tappet chest engines;-

P/N 38G464 1275cc engine with carburetter crankcase closed circuit breathing, AEG542 camshaft and EN16 crankshaft (1971)

While that doesn't say it's a solid tappet block, one tell tale is the cam, it's a spider drive grind of the MKII Pin drive

isn't a 38G464 a factory reconditioned part number though?, so the factory would have just used whatever they could to provide a serviceable item.

All the 38G464 engines I've ever seen have all been S blocks but that's not to say they didn't use GT blocks. I had a chat with Keith Dodd a while ago about these engines, you may be interested in what he had to say :

"The factory took many or all of the S engines at one time for the parts sales and exchange gold seal engine programme. The engines were 38G464N painted black and the N suffix denoting brand new whereas the gold seal replacement was 38G464E.
The engines were black and strangely enough used as warranty replacements in new cars.
I also remember a few cars new registered cars coming in for service with these engines fitted. So they might have been fitted at the factory or replaced under warranty. As the Mk3 was built on a few different standard mini assembly lines it could be that when they came to fit the power lump they might have been short of the engines and drew some back from the parts division where they had been assigned the new number 38G464N.
I used to order both the exchange engines and new engines and often found the ones supplied as exchange were brand new and even had a few 12H397 or 12H398 thrown in as well. I used to buy these units at half the cost of a new unit and strip them down selling off the parts to racers etc which started me on the way to starting mini spares many years later.

This exchange programme also enabled me to by EN40B cranks which often turned out to be new as they did not have enough core units. £30 exchange."