VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Will it run withhout a condenser?

This might be more of a general discussion topic but I started it here because it is electrical.

I am interested in any experiences trying to run a engine on a points ignition system without a condenser in the circuit. I have never tried it. I think it might run but not very well. I am not asking about a failed condenser.

I assume that if it will run the points will arc heavily and transfer a lot of material quickly. A key factor will be whether the points gap gets large enough that the current will no longer arc between the points. If the arc never goes away the field in the coil will never collapse to make the plugs spark. The timing will vary quite a bit because the arc is not consistent.

My father and his brother restored and showed hit and miss engines from the early 1900's. Some of them had a crude points system that triggered a spark from a coil when the points opened. The points did arc so needed "dressing" often. A key difference is that these engines ran at 300 to 400 rpm and only fired every stroke under load. There was no condenser in those circuits.

Any thoughts?

a good test would be to get a car set up and running good, then disconnect the condenser and see what happens. and assume it would vary based on a 4,6,8 cylinder, as the dwell and gap changes.

i know when the condenser was bad the car would barely run, was like it was in slow motion and barely running. hard to explain but that is how i observed and processed it. and if you tried to accelerate it (seed up rpm) it would die

something to do with the magnetic field and the condenser (capacitor) working together. creating a spark, high voltage, rapidly

This is a pretty good explanation of the basic system, only difference is NO ballast resistor on the 1929-32 Chevrolets ;0

goes over basic parts, functions, and what they do in an ignition cycle

How Battery Ignition System Works

I have had an engine run (poorly) with a faulty or non working condenser. I believe that on another occasion I had a an engine run without the condenser hooked up. Both were Model A Fords.

Mike

As a kid I used to fall asleep to the sound of hit & miss engines on the pumpjacks. Simpler times. Thanks for the memory jog.

Hi Rusty

The ignition system in the old engines with low tension igniters was an entirely different duck (or inDUCtance to be more accurate). :-)

Coils are inductors.
This means that when a current flows through them it creates a magnetic field, and when you try to stop the flow of current through that coil of wire and the field begins to collapse, the collapsing field tries to induce a current in that same wire in that same direction.
In other words, a coil of wire (in this case the primary coil winding) tries to resist any CHANGE in current and tries to continue to flow when we try to stop it.

So...
When the points open, the primary winding tries to continue the flow of current and that results in current arcing across the points.
The condenser acts like a spring cushion absorbing that flow, and then bouncing a small amount back in the opposite direction, which actually hastens the collapse of the magnetic field in the coil and induces a hotter spark in the SECONDARY winding than would otherwise occur.
All of this happens in a VERY VERY short period of time.

All of this was to say 2 things:

1) The low tension ignition system in those old engines consisted of ONLY a primary circuit and RELIED on the spark induced when the points opened in the combustion chamber to fire the charge.
Therefore the addition of a condenser would actually KILL the system and stop it from functioning.

2) If an engine that uses a condenser will run, you should not see any significant change in the ignition TIMING regardless of how well or poorly the condenser is functioning.
The condenser does NOT effect the timing of the spark created by the secondary winding of the coil. It DOES have the effect of strengthening that spark, and lengthening point life.
Only the opening of the points determines timing.
And the condenser plays no part until the points open.

PS
These are things you probably already know, but I thought others might find it interesting.
It's been a few years, but I used to tinker quite a bit with old John Deere Model E engines myself. :-)

Hi Ole,

Thanks for those insights. That helps explain the ignition on the last engine of Dad's that I sold in 2007. It was a 1907 Smith's Great Western 5 hp vertical 2 cycle. The governor controlled the arm that opened the ignitor points that were inside the cylinder. Dad used a 6 volt lantern battery and a Model T coil to create that spark.

Some time ago I was testing one of my six volt coils. I was just using a six volt supply, a high tension lead connected to a plug and a piece of wire to make and break the supply. What I discovered was that without using a condenser, the spark was minuscule. Once I added the condenser it produced a normal spark.

A condenser does just what its name implys. It condenses the spark from thr coil. multipies and holds xfor a high discharge at the proper time. A condenser can hold a charge for several minutes.
When I worked in parts a mechanic would bring up a loaded condenser and it could give you a considerable shock in you contacted the lead and body of the condenser.

"Condenser" is just an automotive term.

In nearly ALL other circles it is referred to as a "capacitor".

Same thing, just different terminology.

Thank you for mentioning that. I am going from the era of fuel injection and electronic ignition and working back to carbs and points. I have done allot of modern electronic work but never made the connection between capacitor and condenser.