Classic cars forum & vehicle restoration.

[Luegolover]

I am rebuilding my Healey 100 and having completed the inner bodywork I am starting to put all the mechanicals together and having finished the suspension I am turning my attention to getting the engine, wiring and fuelling installed. And so I am starting to ponder the wiring and specifically the earthing.

I have a kit to rebuild my fuel pump and a that would clearly be +ve earth. However a part of me thinks that I should fit an alternator which would, I presume, be negative earth.

So, do I can my fuel pump and buy an electronic pump that works on both +ve & -ve or do I ditch the alternator idea?

Are there any other considerations?

[ukdave2002]

I'm presuming it's an SU fuel pump? As long as it doesn't have an electronic points conversion, then the pump is dual polarity.
If it has a diode across the points this will need to be reversed, or simply removed, they were never fitted originally.

Dave

[jp928]

If you do go neg earth (recommended due to no of accessories that would then be available to you), dont forget the ignition - some systems, coil especially, are polarity sensitive . I once sold a Rover that I thought ran very sweetly. Week later the buyer rang and said it was running roughly - What have you done? Nothing....well not much - swapped it to neg earth so could fit a modern radio. Swap the low tension leads on the coil please.
If your coil is marked + and - on the turret, make sure they are correctly connected.
jp 26 Rover 9

[lowdrag]

[ukdave2002]

[Luegolover]

Thank you for your feedback and pictures. I don't know what the fuel pump is so will dig it out at the weekend. I suspect it is from 1954 though and so I doubt it has a diode, looks way to modern for the pump from memory.