Mk1 Cortina positive earth

[Rallye Sport]

Got the original engine back in my Mk1 Cortina GT project, about to wire it up and do a test fire.
Is there anyway to test to see if its positive or negative earth?
It previously had a jap 4age in it with a piggy back wiring loom that was negative earth.
Someone has also covered over the 'warning positive earth' in the tacho, not sure whether that was before or after the 4age.
I've got a couple of spare voltage regulators but would rather not find out the hard way

[foxtrot3]

Hi. Are you running an alternator or generator? Do you want it to be pos or neg earth? If running the generator just fit it up and before you connect any wires to it connect a jumper lead to the "live" terminal of you battery and "flash" it across the field terminal of the gene a few times. This changes any residual magnetism in the field cores to suit what you will be running. You should always do this when fitting any generator now days as you never know which way the unit was last used. No idea on the tach but everything else should just work. If the coil has + and - and you are going to positive earth remember to wire + to the points, if it an old lucas coil with "ign" and "cb" on it you can just hook it up as marked as it should be made for positive earth. Cheers MD

[Rallye Sport]

Cheers mate, you nailed it, didn't know which way the generator had been connected before. Ran through the procedure this morn and it turns over and sparks no worries. Haha now to pull it all out again and weld up all the holes from its previous life with electric pumps, fans and relays everywhere... the joys of buying an unfinished project