23-04-2019, 08:49 AM
Hi JonE
The Lucas A7 coils are of the commonplace type where the "cold" end of the HT winding is internally connected to one end of the LT winding, so the return current for the spark plugs flows through them to earth. The metal casing isn't internally connected to anything, but is normally earthed anyway by virtue of the bulkhead fixing screws.
Cheers, John Cornforth
The Lucas A7 coils are of the commonplace type where the "cold" end of the HT winding is internally connected to one end of the LT winding, so the return current for the spark plugs flows through them to earth. The metal casing isn't internally connected to anything, but is normally earthed anyway by virtue of the bulkhead fixing screws.
Cheers, John Cornforth