American MGB Association

North America's oldest, largest and best club for all year MGBs, MGB-GTs and Midgets!!  Established in 1975.


American MGB Association

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for all year MGBs, MGB-GTs and Midgets
Established in 1975

Phone/Text: 773-769-7084

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this is an excerpt from the articles appearing in the OCTAGON

also see upkeep and performance hints on our message board at
and on our Facebook group at

Engine Identification

Q:     I bought a 1963 MGB completely dissembled back in June. The previous owner had the motor rebuilt and indicated it was a 5 main engine. I have not pulled the pan to verify. My challenge is determining if it is an 18 GB or 18 GD because there is no engine ID tag. Can you provide some help?

Tom Bishop
Westerville, Ohio

A:     Here are some photos that have information about engine identification. Here is a bit more:

Engine Identification Engine Identification Engine Identification

The three main MG engines have a tach drive at the rear of the camshaft. The 18GB engine is set for a dynamo, the newer engines also have a set of vertical 5/16-24 threads to accept the rear mount of an alternator. The 18V engines use a very different front engine bearing plate and a single row chain and sprockets for the cam. The 1968/69 rear engine plate has a hole about the size of a silver dollar on the LH bottom.

Hope this little bit helps.

John Twist

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