coil question

[dave`12]

Working on my points distributer, engine hard to start and runs poorly. I just found that the capacitor/condenser wire on the coil is not hooked up. I'm guessing it goes the + on the coil, it's the only place the wire is long enough to reach.

SO, I would like some info on this. Why did the engine run without it, what will happen when I hook it up? Not quite ready to start the engine, as I haven't set the points and dwell yet.

any info appreciated.

dave

[Eddie H.]

The condenser absorbs/cancels out the voltage spikes which are created in the primary ignition circuit as the points open and close. The pigtail on the condenser connects to the terminal that is on the breaker points, and it is grounded through the mounting screw.
An engine will run without it, but it will be erratic and the points will burn up very rapidly.

[dave`12]

Thank you, Eddie. I would like to make sure we are talking about the same thing. I'm not talking about the condenser inside the points distributer, that one was there and hooked up. There is another mounted to the coil itself, with a short wire that will not reach the distributer.

That's the one I'm curious about. Some searching making me think it may just be a noise canceller for the radio, but I hope hooking it up will make the engine run better.

[Eddie H.]

Yep, you have other problems. A noise filter for the radio won't have any effect on how the engine runs.

[dave`12]

Yeah, assuming I'm right, and it is just for noise, I have other problems.

thanx

[Crabass]

An old noise filter (capacitor) that is breaking down internally (and they do, the reason you normally replace the distributor one when you replace points) can act as some value of short to ground. But since yours isn't connected, it's not your issue. However, if it is going bad and you reconnect it, your ignition system status should get worse. Those things are generally inexpensive and not worth taking a chance on.

You really need to know FOR SURE that your cap and rotor are not "leaking" your spark energy (ultimately to ground), and the best way to do that is to get new. The tracks a wayward spark is following can be virtually invisible to the eye.

I've seen bad plug wires drive guys nuts trying to find the source of symptoms like your truck's. The best way I've found to id bad plug wires is to do the "dark test"-------watch the engine running in a completely dark place. If you see a lights show then you need new ones. Take your time, let things get good and warmed up, and look really closely, sometimes the arc is underneath or otherwise not readily seen from above.

Its also a good idea to make sure you're getting full appropriate voltage to the coil.

Just a few basic suggestions.

[davepl]

Random trick: Also worth looking at the engine running underhood in a pitch-black garage (safely, please, don't gas yourself or stick your hand in the fan, etc).

Arcing shows up pretty easily if you look closely. I found one wire-to-ground arc that I could not see any reason for (not even a visible crack in the wire) but relocating it fixed the miss.

Make sure the coil's not hooked up backwards. I've never done it, but heard they will still run but run poorly.