Condensers

[HarryJ]

Two questions: Will 12 volt condensers work on 6 volt cars? Someone awhile back said they are interchangeable. How do you test a condenser?

[Rusty_OToole]

Check the specs for your car, the factory repair manual will have the information. Any condenser of the same value will work.

They are indifferent to voltage but the capacitance (microfarads) should be the same or at least close.

They aren't that accurate from new. If the condenser is perfect your points won't burn. If it is too low material will burn off the + side and accumulate on the - side. Too high, it will be the other way around. Or maybe I have it backwards, can never remember. The idea is, the condenser must be matched to your ignition. We used to check the points when we did a tune up, if they were not burned we would save the old condenser for our own car.

It is possible to charge a condenser by connecting the wire to a battery and grounding the case. If it gives you a shock it is good. Electronics shops, like TV and radio repair places have condenser or capacitor testers if there are any left.

I know old 6V Chrysler products with Autolite ignition used .25 uf condensers.

If you need one for your car you can use one from any electronics supplier, if it will not fit in the distributor you can put it on the coil, it will work fine. Old English motorcycles were set up this way because there was not room enough in with the points.

[Friartuck]

Rusty's explanation above is essentially correct. To test use an analog (needle) type Volt Ohm Meter aka multimeter, connect the test leads to the condenser and using the RX1 ohm resistance scale, flip between the positive and negative polarity switch settings (assuming your meter has this feature). If not switch the test leads quickly. The needle should swing across towards zero and gradually rescind as the condenser charges. This is not a full proof test, but intended to check if the condenser is shorted. If you have a newer type digital meter, it may have a capacitance scale and you can simply check the condenser value. Typical auto condenser values would be .22 to .27 Micro Farads (uF). I would favor newly manufactured condensers versus NOS as the older ones may have the insulating paper breaking down and shorting out the condenser.

Edited October 1, 2014 by Friartuck
Revised Resistance Scale sentence (see edit history)

[Rusty_OToole]

Friartuck can you tell me if an ignition system uses a fixed or polarized capacitor? Would it be better to use an electrolytic or orange drop? And what voltage would be required?

[rsb]

You can't reliably test a condenser with a multi-meter. You really need an old-school capacitor analyzer to test the insulation resistance / leakage. If the condenser's internal insulation is breaking down, using it will only hasten its failure. You should be able to substitute a modern .22uF, 600V or higher voltage rating film or poly capacitor (orange drop). They are non-polarized. I have used this method to re-stuff an original condenser when appearance/originality is important.

[HarryJ]

Hey guys.....Thanks................Question #3, can I test the condenser by simply disconnecting it from the points (wire end) leaving it connected to the inside (ground side) of the distributor? The reason I ask is that the car in question is an "L" Lincoln and to remove the condensers requires removing the distributor from the car and dismantling the distributor. where replacement would require resetting the timing.....LOTS OF Work!

[Rusty_OToole]

You could try disconnecting the condenser and attaching a new one either to the outside of the distributor or on the coil. It does not matter where it is, as long as it is attached to the wire that goes from the coil to the points. And, if it is an electrolytic capacitor, respect the polarity ( connect + and - as appropriate, for your + or - ground car).

If the car runs better, that tells you the problem was the condenser.

[Rusty_OToole]

Many older cars had a distributor that had to be removed for service but they always attached it in such a way, that you could take it off and put it back on without disturbing the timing adjustment.

[Friartuck]

Because the condensers of a model L Lincoln were mounted under the points plate and required complete disassemble, in the interest of time and convenience it was common practice to "hang" condensers on the outside of the distributor on the low voltage coil wires. It works but unsightly. Bite the bullet and replace the ones under the point plate. A NAPA condenser (DR-70) fits nicely, but will require extending the lead a little. I believe where the condenser is mounted makes a difference hence why they are mounted closest to the points. Mounting condensers directly on the coil (6 feet of wire away) may not provide the full benefit to the points.

[Beltfed]

Friartuck, I've works in electronic for nay on 45 years. In all those years I have never seen a VOM with a "zero ohm resistance scale". :confused: Just kidding with ya! They ones I own have a resistance multiplyer scale, Rx1 to Rx10,000. When working around cars they are my go to meters as I hate watching the numbers jump around on the DVM's. I do use the DVM's with the clip on(around) amp meter for current measurements.

[Rusty_OToole]

How come the coil is 6 feet from the distributor? Many vehicles came with the condenser on the outside of the distributor, or on the coil. I don't think it makes any difference. If it did, having it close to the coil would be better.

[Guest R. W. Bibb]

Rusty; The coil is 6 feet away so it can be mounted with another coil. The model L Lincoln uses a point set, condenser, and coil for each cylinder bank. The distributor is on the left front of the engine and the coils are mounted under the right side of the dash. The wires all go thru a nickel plated conduit to the distributor. This makes for a pretty engine. I have a 1929 L myself. I also have a Sun distributor machine that I

use to service my distributor. It's the most accurate method of getting the two banks timed together. Also; the length of the condenser lead affects its capacitance. Hope this answered your question(it made me smile!)

[HarryJ]

Thanks ! This has been quite educational.

[HarryJ]

Thanks ! This has been quite educational.