maok

Sam it depends on idle speed and the pulley size of the alternator. My '28 idles around 450rpm and needs a good rev of the engine, my '37 idles around 600rpm but still needs a little rev to get the alternator to excite.

With the single wire alternators, you need to give the engine a bit of a rev to excite it. The ammeter should kick in then, its a little bit of an annoyance but not much.

How did you install the oil pump gear? The distributor is driven by the oil pump.

Hi Nigel, I'm in Brisbane as well, I have '37 Dodge with probably the same 25" 218 which I just recently converted over to the 32/36 weber (style...lol) downdraft. Working well so far, though running a little rich. The C6J1 may run a little lean but should be ok imo. Does it have have an adjustable main jet?

Yes, it would, and will work fine with 2 ga, 0 ga, 00 ga but with less voltage drop.

I had a similar discussion a few years ago on the aaca forum with a member there (IIRC Bloo), a very knowledgeable poster. He did the swap in his '36 Buick(IIRC) and was surprised that the results weren't what he believed to be. He noticed the slight increase in amp draw with the 12 volt battery.

The thing is, your use of the power equation (P=VA) is misused. The power (watts) is higher with a 12v battery than a 6 volt battery because the 12v battery causes the engine to spin faster.

Mate, do the experiment, you seem like a person who needs to know, with a scientific curiosity. Measure the current (with a clamp meter) with your 12 volt battery/4ga, do 2ga, and do 0ga. Now swap to a 6 volt battery do the same and compare. Apples for apples.

To add to my example of the starter getting stuck, imagine the opposite, ie less load on the engine - remove the spark plugs, remove the fan and the accessories that attached to it, remove the flywheel (actually this not possible because starter turns the flywheel), the current draw will be dramatically reduced because there is less resistance to the pinion gear turning of the starter motor. People often complain about the 'starter is now turning slow' and the automatic response from most is 'you need larger battery cables', even though it was turning fine before. The article above talks about battery terminals and corrosions, which is the most likely cause of these issues and the status of the battery. Battery cables don't reduce over time but corrosion, terminal and battery quality do.

Yes, definitely current draw, but current draw is dependent to the resistance to the starter motor pinion gear, ie. engine size, compression, etc. What happens when the starter motor gets stuck? Current draw increases dramatically, nothing to do with battery voltage. Actually, a 12 volt battery on a 6v starter will draw slightly MORE current than with a 6 volt battery in the same engine because the starter spins faster with 12 volts (than 6 v) and hence slightly more friction is created in the engine. Do the experiment, use a clamp meter over the battery cable and see the results yourself. Current = torque Voltage = spin speed. Modern engines with 12 volt starter motors have hi torque gearing, less friction, are better balanced and designed to start within the first stroke hence do not need the cable size of yester-years.

Cable size is not dependent on the battery voltage, it's dependent on the engine size.

If you havent mentioned where your negative cable (thick cable) from the battery is attached to. As explained above, if still positive ground, then negative (thick cable) from battery goes to starter and positive (thick cable) from battery goes to transmission. Or reversed if someone tried to convert to negative ground. I will repeat what Tod said - DO NOT CONNECT THE CABLE ON THE STARTER TO THE ENGINE BLOCK!

I've ticked one off my list, '36 Airstream, but its only the 6. Hopefully one day a 1932/33 Imperial tourer or '34 Airflow Imperial, though my pockets are very empty currently, only if I had an offer on my '28.

I have been running a Pertronix module for 5 years in my '28 Chrysler and a few months now in my '37 dodge, when wired correctly and most importantly, the current flow through the module is correct, which is probably why people have failures (when it's not), via the right coil resistance, Pertronix mod works well.

You by-pass the stock regulator, these alternators have a regulator built-in, so one wire to your ammeter or wherever the 'bat'wire from the old regulator was connected to.

I second second the sentiment, I have two of his conversion, working well and was easily adapted.

Have by standers push start the car...in my experience, they don't mind pushing a vintage, actually, they volunteer freely...?

This pic is from my '37 MC truck with the same 25" T38 engine manual,

If you don't acquire the Airflow, you will be kicking yourself down the track. You will be telling others how you had a chance to own an Airflow...? IMHO, its the most iconic Mopar. It does have a face that only a mother can love but...

I am in a similar position, looking at a '34 Chrysler Airflow with historic Australia provenance and a '36 Chrysler Airflow. Oh the luxury of options and limited space....lol IMO, of the early Mopars, surely it would be the non Imperial Airflows that will appreciate in value significantly, Love the dash on the Desoto.

What is your idle speed? Are you showing charge on the ammeter at idle? The alternator may not be spinning faster enough at idle, you may need a smaller pulley on the alternator.

Yep, I mis-read your original post, I thought you had the Ignitor 1 module.

Check the battery terminals, coil connections, and ammeter connections for a clue to what may have been done for polarity.

Here is a screen shot from the Pertronix site; If you have the 1.5ohm unit from above table then it would be used with a ballast resistor of 1.5ohm for a 6 cylinder engine.

Were they for a 6 volt system?