1963 Herald 1200 Convertible - Positive or Negative Earth?

[benblaney]

I have a 1963 Herald 1200 Convertible, North American delivery.  Vin: GA/120284-LCV

I want to put a pertronix electronic ignition on it, but I need to know if it's a positive or negative earth (or "ground", as they say in North America).  My 1962 Herald 1200 Coupe was a negative earth, but that was a UK car, and I don't know if they'd have been different.

Any ideas from the braintrust?

 

[Pete Arnold]

Surely the easiest way is to look and see which battery lead is bolted to the chassis or bodywork. That is the ground. 

[benblaney]

Quoted from Pete Arnold-

Surely the easiest way is to look and see which battery lead is bolted to the chassis or bodywork. That is the ground. 

Ah yes, I should have said - sorry.  I'm 20 miles away from the car, and self-isolating.  So I was hoping to get the correct parts ordered so we can get cracking as soon as this pandemic is under control.

And your reply makes me think something else: is it possible that the same model from the same manufacturer has two different configurations - some being positive ground and some being negative ground? Or maybe it could have been changed at some point in the car's life (I don't understand electricity enough to think through the whys and wherefores of that).

[RobPearce]

Some cars designed in the late 1950s would have initially been positive earth and then, at some point in production, were updated to negative. The WSM shows early 1200 Herald as positive earth, later ones negative. It gives a changeover date in 1968.

However, there are no polarity sensitive parts on a standard production Herald. To convert from positive earth to negative you only need to:

- swap the battery terminals

- swap the ignition coil terminals

- re-polarise the dynamo (by connecting to the battery a couple of times)

So ultimately, the only really sure way to know which polarity your car is would be to (get somebody to) look at the battery.

[thescrapman]

Have you got a photo of the under bonnet that might give a clue?

[benblaney]

Quoted from thescrapman-

Have you got a photo of the under bonnet that might give a clue?

Good thinking.  Here's the only one I have - because it's 20 miles away and New York is on lockdown.

https://imgur.com/a/FLXNNsH

Image added by Steve Weblin Forum Moderator

[nang]

I see you have an alternator,so most probably negative earth.

Tony.

[herald948]

Quoted from nang-

I see you have an alternator,so most probably negative earth.

Tony.

Agreed! That vintage of 1200 would have been positive ground originally, but likely that's no longer relevant, given the alternator. (Conversion is/was as others have noted above.)

[Mark Hammond]

Certainly it was +/ve earth when built, the alternator gives it away as -/ve earth now....

 

Mark

[Bitumen Boy]

It's probably negative earth, but do be aware that Lucas once made positive earth alternators. I doubt you're too likely to find one now, but if ordering polarity sensitive parts Sod's Law could easily come into play... 🙄