I have a 1967 MK2 340,

Car is positive ground with a Lucas alternator (11AC), remote regulator (4TR), alternator relay (6RA) relay ignition relay (3AW) for the ignition light.

The ammeter reads neutral at idle and a slight charge with increased speed.

Should it keep running with a battery cable disconnected, as it dies out until it is reconnected?

Is the alternator working properly as the voltage at terminal B does increase with increased RPM to 14-15 volts?

Will it do any harm if the 3AW ignition light relay is disconnected (missing). I am considering replacement with solid state 3AW (38706X). Does anyone have any experience with this relay?

Thanks,
Ron

 

As far as I can see, everything seems reasonably OK, if you have a fully charged battery. The voltage should go up to about 14-15 when charging, and drop a bit when the battery is fully charged, but should always exceed battery voltage, which will be about 12-13 volts. Do you see amps on the ammeter immediately after starting the car ? The alternator is designed to work only when properly connected to the battery.

I am not an auto-electrician, so wait a bit until somebody more knowledgeable posts here. I wasn't aware the 240/340 models had alternators, it was a dynamo on my Mark 2.

 

If it stalls with the battery removed I'd immediately say a bad alternator. I wonder if you have some bad diodes with only one supplying the voltage but not enough to supply the current? Those 11ACR's are pretty robust, too bad you're not closer as I have all the bits just laying around. That said, they're still pretty cheap at the shops to replace.