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?
A: Here are some photos that have information about engine identification. Here is a bit more:
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.
More tech items at