Will my 12v timing light and dwell meter work for my 6v/8v 1949 Cadillac?

Hi all,

FIRST - A big thanks to all who responder to my previous questions.

SECOND This weekend I will be fixing the exhaust leak and installing all new ignition components in my 1949 Cadillac with the 331 engine.

I am currently using a 8volt tractor battery for starting power, seems to work very well.

My question is... All I have is a standard timing light, I assume it is 12volt, that's all I have ever used it on. I also have your basic, Equis Dwell meter, I assume it is 12volt, that is all I have ever used it on.

Will these tools work on my 6v/8v Cadillac ignition system?

Thanks for your help ahead of time, I am looking forward to driving my brand new, 1949 Cadillac Motorhome, home this weekend if all goes well, (it is stored at a friends house, I already have 2 1959 cadilllacs and a 1960 cadillac at my house)

link to a picture of the Cadillac Motorhome,
http://www.dnc.net/users/sanger

thanks,

Mike and Lynn

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If the timing light is an old one that only uses the high tension then it should just work. If it is a newer one (in the last 30 years or so) with a couple of leads with battery clips, then you will need some 12v power. I have made mine work by parking my new car close enough to the old one to clip the timing light on to the 12v battery, then I attached the pick up lead over the #1 plug wire on the old car. It worked fine.

I don't know about the dwell meter. I always set the points on the old car with a feeler gauge.

Best of luck, Tod Fitch

Though you didn't ask for any advice in this area, I'm going to strongly recommend you go away from the 8V battery and replace it with a 6V Optima battery. No, I don't sell them! I've been down the 8V path with my '53 Ford pickup, and it doesn't work that well. The Optima batteries work great - many of the guys in my local Early Ford V-8 Club run them. Lots of cranking power, and they don't seem to mind sitting around unused for months. Do that with conventional lead-acid batteries and they die a quick death. The Optimas look expensive at first, but they last longer than most conventionals. 8V batteries

aren't cheap, either. The problem with the 8V is that it puts a strain on everything else in the electrical system.

Probably not, as is. For my 6V positive ground Fords and my 12V Sears timing light, I hook up the timing light power leads to a 12V battery and clip the inductive pickup around the plug wire with the arrow going away from the plug instead of toward it. If you are negative ground, I'd put the arrow toward the

plug.

I've never figured a way to use my dwell meter on these vehicles. A dwell meter is essentially a dedicated volt-ohm meter, so it is not surprising it doesn't work on a 6V.

Hope this helps,

Given the resistance of the dwell meter itself you could put a resistor (preferably a large wattage one) in series with it of equal value. In other words, if the meter measures 200 ohms then you get a 200 ohm 5 or 10 watt resister and put it in series with the '+' lead. This will drop equal voltage across each part which will drop 6V across each. You first need to get a reading on what the dwell meter is rated at. This may or may not provide an accurate reading though based on the fact that the dwell meter may need to vary in voltage to provide a reading. If it varies with current then it will work OK. See below for examples: http://www.physics.uoguelph.ca/tutorials/ohm/ Q.ohm.intro.series.html

A proper dwell meter takes the signal (no impedance stated but usually quite high) from the points and drops it with an internal diode to an internal standard voltage and then measures that duty cycle (the dwell) on the dial. Otherwise, the 6V would indicate about 1/2 of the dwell reading that the 12V system would and what's worse, because all cars have differing voltages (the coil resistor is in the line) on the points, the dwell would end up being different with each car along with the fact of different systems have differing amounts of inductive kicks (even from the different plug gaps) on the line making things even worse.

answers that question.

Thanks,

I will give the suggestions a try this weekend when I go to work on the old girl