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MG Midget and Sprite Technical - Early Sprite Cylinder Head

Could someone please tell me what the cylinder head casting number was for the early MkII Sprites of 1961?
J.P. Parnell

My 1961 Mk2 Sprite (948cc) has what I beleive to be the correct head which is casting number 12A185.
This gets very confusing as its apparently the same number as the early Coopper S although it is a different head.
Les
Les Robinson

Les dont get confused mate

I understand the basic casting then had differing things done to it to decide wot it done nextly.

i.e chamber machining and valve sizes and all

The Longbridge engine plant was tremendous, I used to drool whenever I was able to wander around it. A couple of my neighbours worked there back in the day, tales they tell!

My mate Dave still insists in the face of all the evidence that any MG lump should be RED... Including midgets.

But he does have some wicked works tools to borrow so I never call him a numpty.
Bill

Bill
From what I can gather, and I asked this question not too long ago, is that the head identification is 12A185 - small bore.
I understand what you are saying but there is no other part number or id that is associated with it, or at least that I could find. However if there is then please let me know as that will solve yet another mystery!
Thanks

Les
Les Robinson

I doubt if there's a mystery Les
12A185 will almost certainly be a casting number rather than a part number
It's what is done during production that determines the finished use (and thus Part Number) the head gets.

I see from my very old Moss Sprite parts catalogue that the head number is 12A1455, but if it was made from casting number 12A185 it wouldnt be a surprise

I seem to remember that myy old Midget 1275 head had the casting number 12G940 (gone now to live on a Sprite) but the MG Metro head that I now have on Lara is...12G940

All down to subsequent work done to it

Maybe it could make a fascinating magazine article or even a small booklet if there were enough of the old time machinists around to talk about it. I will ask Dave, my mate if he has any idea about the whys and wherefores

Tomorrow
Bill

Bill
I think the 12A1455 (I also have a reference for a 12A1456 and 2A628)was for the 9C engine used in the Frogeye. The Mk2 Sprite uses the 9CG engine and has a larger inlet valve.
Too many numbers and variants. I gave up in the end cos it was doing my head in!
Les
Les Robinson

me too

but I will ask Dave tomorrow if I can get to see him
Bill

I know this may add further confusion but.....

948 Sprite has 12G202 and I think the early 1098 version had the same (This is where I am not certain), the later 1098 10CC engines were fitted with with the 12G295. All these were for the 'small bore' engines.

The early Cooper S was fitted with AEG 163 which was soon replaced with the 12G940 (in it's MANY guises).

I'm sure there is still more info to come forward...

I THINK Les, that 12A185 is stamped on the S head whereas 12A185 will be a casting number that is 'cast' into (raised) the 'small bore' head. Yep, confusing....

Mark.
Mark Boldry

FWIW, Neil Cairns' booklet says :
12G 202 - 997 & 1098 cc
12G 206, 12G 295 - 998 & 1098 MG (maybe the 998 is a typo for 948)
12A 185, AEG163 - all Cooper S
David Smith(davidDOTsmithATstonesDOTcom

This is a very confusing subject, as there is the small-bore 12A185 and the Copper S 12A185, which are completely different animals.

What I think Mark is referring to is the number stamped on the late Mk3 S head - which was an 11-stud 12G940. That number is 12G1805. See pic...


Dave O'Neill 2

I have a GAN1 with a 12G202 head, but fitted those two last years. It runs well with it.
my second gan1 seems to have a standard head, but there is no casing number on it. Perhaps the casing number is under the rocker cover.
laurent
laurent

Dave, you will be correct, that is the number I was thinking about.

David, the 998 Cooper had the 12G295 head fitted as standard.

Sorry, without getting involved in more research (which unfortunatly I don't have time for at the moment) I can't throw anymore light on this subject.

Mark.
Mark Boldry

I have found a copy of the BMC service parts list for the Mk2 Sprite (948cc)- dated March 1961.
For the cylinder head the following numbers are listed :-
28G132 - head assy including valves.
12A184 - head with valve guides.
Nothing shown for bare head.

Probably not much help but.

Les
Les Robinson

Hi Les,
you are right, on the Mechanical and service parts list

9C was 28G86 replaced by 28G161
9CG was 28G132 replaced by 12A184
10CG 28G191 and 28G222

The 12G202 was for 997cc cooper and have more capacity and larger valves.
So 12G202 should decrease the combustion ratio, but put more gas in the engine.
What I can say, is the 12G202 is pretty good on a gan1 car.
laurent
laurent

This thread was discussed between 10/02/2008 and 15/02/2008

MG Midget and Sprite Technical index

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