Gauge Wire

[Flyboy1st]

I converted my 29 coupe to 12 alt, 60amp, neg ground. I would like to replace the battery cable to the starter with 2 gauge cable instead of the 1 gauge cable that ford used for the 6 volt system? Will the amp draw to the starter be too much for the 2 gauge cable verses the 1 gauge cable. Anyone have experience with using 2 gauge cable?

[David R.]

The current should be less at higher voltage, so you should be able to get by with smaller cable, in theory at least.

[rotorwrench]

12-volt can generally always use 1 less normal American wire gauge size than a 6-volt system. It doesn't hurt to use the larger but you just don't want to go too small. It all depends on the current flow required in the particular circuit in question. With 12-volt, it will be even more important to have each accessory circuit fused. The only exception are circuits that are intermittent.

[Synchro909]

You didn't say if you converted the starter to 12v. If you haven't, a smaller cable and as long as possible will drop the voltage to the starter a bit and help it survive the higher voltage for longer. The same for the earth cable. I used a very small and long cable from a small Japanese car for both power and earth on mine and could still go further. I bought them from a wrecker's yard. The starter in a Model A doesn't draw very much, neither do some of those small cars and look at how small their cables are.

[Bill G]

Why not just stay with the larger gauge? Less work in the long run.

[Synchro909]

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Originally Posted by Magicbox51

Why not just stay with the larger gauge? Less work in the long run.

I'd be happy to do that - once I converted the starter to 12v. I know there are some who say they run the 6v starter on 12v with no trouble but IMO, it's only a matter of time.

[Badpuppy]

Originally Posted by David R.

The current should be less at higher voltage, so you should be able to get by with smaller cable, in theory at least.

The current will double at 12V unless the starter is converted. Technically, the cable ampacity should also be doubled to accommodate the increased current. However, due to the intermittent nature of the starter operation the insulation on the stock cable is unlikely to melt immediately, but may be compromised over time.

As Synchro909 mentions, smaller, longer cables will increase resistance and lower current, but not that much unless they are very small and very long, and well insulated and ventilated. Extra resistance will also decrease battery charge.

[Flyboy1st]

Originally Posted by Magicbox51

Why not just stay with the larger gauge? Less work in the long run.

I am adding a cutoff switch and will use the #1 cable from the battery to the switch and #2 cable to the starter, #2 cable is cheap and local. I have not converted starter to 12V, how difficult is that?

[rotorwrench]

Only the fields need to be changed since they don't need as many windings in the field as the old 6-volt stuff did. The armature would still be OK. The 6-volt starter will just turn faster but I doubt if it would hurt it unless the engine had problems where a person might run it too long and overheat it. A person should let any starter cool off after running it a good bit no matter what the voltage is.

[Badpuppy]

Originally Posted by Flyboy1st

I am adding a cutoff switch and will use the #1 cable from the battery to the switch and #2 cable to the starter, #2 cable is cheap and local. I have not converted starter to 12V, how difficult is that?

http://www.diabloas.com/daspdfgrafix...tarter-12V.pdf

I think the vendors sell the coils preassembled for 12V.

[callcoy]

I am of the school that runs 12 volts into the 6 volt model A starter, but I do not use the old style Bendix. I used to run 36 volts into the 12 starter to fire up the Rear Engine Dragster for years without a problem.