How to I connect up this alternator?

[VicS]

Hello, thanks for this thread has begun to clear up alternator wiring for me. I am stuck because my replicas Lucas A127 which is identical to the picture posted here except it lacks a B- stud? If you are still on this group any suggestions welcome. Thanks

Perhaps your replica A127 does not have a negative terminal because the case is negative and the connection would be made via the mountings.

That will be a problem your engine has an isolated negative system otherwise perhaps just add an earth connection between block and alternator case to avoid the possibility of poor connection via the mounting

I cannot now see your original pictures only PVB's

 

[Acdbox]

Hi Vic's, thanks for your reply.
Basically what you said makes sense and is what I suspect is actually the case. Though I am hesitant in making a second connection back to the battery as I thought this might contribute to electrolysis of the hull/engine? I thought it was meant to be a single negative return to the battery to counter this?
Admittedly still learning so someone with more experience's views are welcome.
Thanks once more
Andreas

 

[Big John]

I purchased a Lucas manual many years ago called Alternators XPB400(EN) which covers all the alternators manufactured by Lucas and includes all the diagrams and terminals. Can you try your local library to see if it is in their technical section?

 

[earlybird]

AS VicS says, the A127 is negative-case , my old example did have a -ve terminal, but it wasn't essential AFAIK.
Some Lucas alternators have double 3/8" Lucars for output, joined internally. This was because a single 3/8" Lucar was rated at 35 amps, thus insufficient most alternator outputs, and also the wiring loom could have 2 thinner wires rather than 1 rated at 70amps. I guess the stud terminal of OP is also connected internally.
Lucar ratings are based on their width, not colour of sleeve. This indicates the wire size for the crimp, although, obviously, this influences the current rating of the circuit.