MG Car Repair: Best Gasoline for 1979 MGB - Part II, spark plug gaps, vacuum advance

Question
Barrie, thanks for your very prompt and thorough response to  my initial question. You said that you might be able to provide a bit more detail with the engine number.

Here it is, hoping I got it right from the plaque, which is a little hard to read in parts:

18V883AEL 028625

Thanks again!

Answer
Hi Bobby.  Yes, the numbers look right for a USA specification engine made in 1978 for an MGB with overdrive and low compression (8:1).  

There were two specifications of this engine, one for California and a different one for the rest of the USA.  The only difference that I can see is in the distributor vacuum advance unit.  The Californian one had much less vacuum advance, which reduces emissions under part throttle at the expense of a higher fuel consumption.  The vacuum module is attached to the side of the distributor, and if you look closely you should see some tiny numbers stamped into it.  For California it was (5-11-7) and for the rest of the USA it was (3-11-12).  Unless you live in California, I would advise you to fit a non-California module.

Rocker clearances should be set to .013 inches when hot (0.33 mm).  Timing should be set at 10 degrees before TDC at 1,500 rpm using a strobooscope.  Spark plug gaps should be .035 inches (0.90 mm).