got my 73 v-12 out the other day after a year and while i was driving it started to get slow. made it home and now the spark from the coil is is so weak i can't hardly see it. any ideas

 

Coils are relatively cheap...But, check resistance across the primary (against the standard)
My first instinct, after that, would be wires, and caps....
How long have you had the same plugs? Pull the plugs and look at the condition...Clean and regap...
Edward

 

Is it still the original Lucas OPUS system ? The amplifier on these early V12 ignitions tended to fail due to heat. An autoelectrician I once knew who worked at Lucas, told me all the technicians called it "OPLUS". As I recall, the amplifier had to be moved to the front of the car away from the heat.

 

car is the same as it was made.same plugs, only 42 k on clock. drained gas , put 10 gal back in , got new battery, and bang it 's up and running again. rough but running.may have put 300 miles on it in the last 10 yrs. it's charging so don't know way a battery would do that

 

All about Lucas OPUS here: -


V12 IGNITION SYSTEMS / AJ6 Engineering


and here, (and how to check it)


Reopus Ignition | The Lucas OPUS Ignition amplifier