1920 DB Battery cable guage?

[Lahti35]

I've got what looks like 4 gauge cable from the starter/generator inside conduit. The battery cables look like replacements from a later date. What gauge should the positive and negative battery be? Also 4 gauge? 

 

My roadster came to me wired for 12V negative ground, is this correct? I found information saying they switched to positive ground around 1922?

[Minibago]

Your car should be 12 volt negative ground.

 

I would use 2 gauge for battery leads.

If in doubt go big.

[Lahti35]

12 hours ago, Minibago said:

Your car should be 12 volt negative ground.

 

I would use 2 gauge for battery leads.

If in doubt go big.

My issue is that I'm stuck with 4 gauge between the starter switch and starter because it's inside armored cable, it appear to be the original cable. The battery to starter switch is old 1 gauge with a cloth cover, the battery negative to ground cable is the braided type. Looking at a 1922 DB wiring diagram the cables from the starter and battery to the starter switch both look to be in the same size galvanized conduit which fits 4 gauge but no bigger. 

 

Normally I up battery cables to 2/0 but being this is 12v and the longest cable is 3' I'd like to stay stock.... I just don't know what stock is for the other two cables and I'm just guessing they are all the same size....

[nearchoclatetown]

To ME the important piece of cable to upsize goes from battery to switch. The factory size in the sheath should be good.