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MG Midget and Sprite Technical - Engine numbers - factory rebuilds

I think I know the answer to this one, but maybe someone has some other source of information.

I have an engine, with a rivitted engine plate number 8G10 R M413 AD I believe this was a factory recondition unit, but unlike the original numbering, this provides no interpretive information. Its just some sort of sequential job lot numbering system. Is that correct?

The engine is currently roughly painted all over in bright yellow, though I believe it would originally have been a goldseal (full) or a silverseal (short) engine. According to log book records this has been with the car since at least 1980.

Strangely, the log book has it entered as 997cc, though I don't believe BMC made any in-line engines to that size, just the mini cooper transverse ones.

Is there anything else I can learn about it?
Guy Weller

Guy, you are correct that it is a factory recon gold seal engine and I agree that the numbering cannot be interpretated as with the original numbers. 8G relates to the BMC part number and applies to all gold seal engines I believe. I do not know what (if any) relevance can be gleaned from the rest of the number but guess that the 10 could signify 1098, but equally could mean something entirely different or nothing at all.

Trev
T Mason

all the gold seals I've ever seen have been prefixed 8G 180E which I understand to be the BL part number, usually followed by 2 letters and 5 digits. I'm guessing the AD you've put on the end is actually set below or slightly lower than the main number? I've seen 3 like that and conjecture it's the initials of the engine builder. BTW Silver seal are prefixed GSE1106E.
David Smith

Thanks both. As I thought then.

David you are right, the letters AD are below the longer number. And are in fact punched in rather than reverse embossed (raised) like the others, so added later, possibly by the builder as you suggest. The others are as I indicated, with those spaces between letters and numbers: 8G10 R M413

Any thoughts about this 997cc capacity on the log book? I seem to remember reading somewhere (Vizard??) that a very few , very rare in line engines were made to the 997 Cooper size. But I suspect it is just an admin error! The car is a 1960 Frog, so should by rights have a 950 engine. Its going to get stripped down and measured anyway.
Guy Weller

Guy,

8G10 is correct for a 948 engine.
ISTR Silverseal were also complete engines but not remanufactured to the higher standards as the goldseal, it had a shorter warranty from memory.

R.
richard boobier

I recall reading, but can't now remember where, that the two letters following the prefix referred to the overbore size and the crank grind. When I looked at this for my Gold Seal which is a later 8G 180 1275 unit, I worked out that it had a +20 overbore indicating it was now 1293cc?
I've never risked taking the head off to investigate further for fear of turning into Prop!
I'll keep looking for where I found it.
Matt1275Bucks

This thread was discussed between 13/02/2013 and 14/02/2013

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