Trouble shooting a dual point ignition system.

[cudaken]

 
OK, it been a long time since I have had to do it and just want a refresh. Car is my 68 Road Runner with Accel dual point. I have to repair the wiring harness so I have been running her by hot wiring the + side of the battery to the - side of the coil. And yes like a dumb ass I by past the ballast resistor .

More than likely I cooked the condenser and maybe the points. I know I have power to the - side of the coil. So my questions are.

How do I check to see if the coil is good. I know I pull the coil wire and see if there is a spark when I ground it. I am guessing I should be cranking the motor. But, if the condenser is bad, there won't be a spark. Hum, I think I may just answered my own question. 

I guess I need to pull the cap, move the points and if there is no spark I have cooked the condenser or have no power from the + side of the coil to the points. 

Anyway, give me your thoughts on tracing down the problem. I know, it is time to do the conversion.

Cuda Ken

[Pete in NH]

Ken,

The + side of the coil should go to the battery voltage. The - side of the coil should go to the points. Dual points are a bit of a pain to set up as both sets of points must  exactly the same time.I would start by making sure both sets of points have clean contacts and don't have any oil or grease on them. To set them up first disconnect one set of points and set the gap and dwell, then disconnect or block that set and reconnect the other set that was disconnected and set the gap and dwell on that set. When both sets are adjusted, reconnect both sets together again. Gapping points and setting dwell, been a long time since I've done that. Electronic ignition made all that go away.

[cudaken]

My God, my poor Road Runner does not stand a chances anymore!  I am just plain getting ate up!

I just checked and I have the + side of the battery going to the - side of the coil. + side of the coil going to the points! 

What amazes me is she ran for 10 + hours and ran well! 

It does explain a few things, like when I first tried to start it the ballast started smoking with the MSD Blaster Coil, pretty sure it cooked. Then Allen and I replaced it with a stock coil and hot wired it and ran great. (Reason we hot wired it was because the fusible link was crispy from another F Up I made with a battery charger.) 

I swear, I use to be sharp! 

Messing up again, Cuda Ken

[b5blue]

Ken,

The + side of the coil should go to the battery voltage. The - side of the coil should go to the points. Dual points are a bit of a pain to set up as both sets of points must  exactly the same time.I would start by making sure both sets of points have clean contacts and don't have any oil or grease on them. To set them up first disconnect one set of points and set the gap and dwell, then disconnect or block that set and reconnect the other set that was disconnected and set the gap and dwell on that set. When both sets are adjusted, reconnect both sets together again. Gapping points and setting dwell, been a long time since I've done that. Electronic ignition made all that go away.

It's been a long time for me also but I do not think "both sets of points close at the same time". They are very slightly out of phase, dual points on the cars I maintained were designed to increase dwell. One closes and the other closes just slightly later and that gives a longer shot to the coil. I adjusted many on several different cars/trucks back in the day and always very carefully set each point to the exact gap called for and let it rip. Even my old 72 Datsun pickup had dual points and for a 1600 four banger it screamed.
  It's easier to do by letting the dist. rest at a position where you rotate the shaft into advance at the peak to set gap by turning the rotor. Hold, set, tighten and recheck until both are perfect. 

[Pete in NH]

I just reread my first post and I see I left out the word "open". Both points must open at the same time or one set with short circuit the other.

[cudaken]

 Pete B5 Blue, thanks for the answers but I think you missed my question. I know how to set the points. Main thing was how to test the coil and condenser.

Beside the fact I mess the dam thing up by wiring it wrong,still cannot believe it ran that way.

On the coil, use a multimeter and test to see if I have conductivity from the + side of the coil to the - side of the coil. If I have conductivity then the coil should still be good, right?   In which case the condenser should be bad. I will all so look at the rotor as well, cold be burnt up I guess.

Reason I don't think it was the points, car was still running great the last time I shut it off. I will look at them as well, I have learned just because it cannot be the problem does not mean it is not the problem.

Cuda Ken  

[b5blue]

http://www.wikihow.com/Test-an-Ignition-Coil   try this....

[b5blue]

Then read this....  http://www.smokstak.com/forum/showthread.php?t=21175   

[A383Wing]

coil will run on reversed polarity, will just have lower total voltage output...

I say replace the condenser, connect the coil correctly, and fire it up..unless the points are melted, which I doubt, it should be fine

[cudaken]

coil will run on reversed polarity, will just have lower total voltage output...

I say replace the condenser, connect the coil correctly, and fire it up..unless the points are melted, which I doubt, it should be fine

Thanks Byran that is the answer I was looking for! Should have know and just asked you in the first places!  Pray tell, how do you happen to know it would run with the wires backward? 

B 5 Blue, thank you for the link as well. 

Cuda Ken

[Pete in NH]

Ken,

While you are correcting the coil wiring, I would put the ballast resistor back in. Without the resistor the coil current will build to a higher value and might eventually damage the coil. With the ignition key on and the engine not running it will for sure let too much current flow through the coil. Without the resistor it will be hard on both the coil and the points.

To do a quick coil check, disconnect the  - coil wire at the distributor and touch it to ground when you pull it off of ground you should get a spark from the coil high voltage lead if you hold near a ground. Hold the - coil wire by the insulation as you will get a kick back voltage when you pull it off ground and you'll feel it if you're holding the bare wire.

For the capacitor, you can use your multimeter in the ohms position. With one meter lead on the condenser wire and the there on ground you should not get any reading. If you do the condenser is shorted. That is only half a test as the condenser could also still be open and bad. Brian is right the best check is to simply replace it if you think it might be bad.

[cudaken]

Pete, I all ready have the condenser and will install it when weather permeates. While I will fire her up straight hot wire to make sure she runs. I have the wiring harness repaired and will install it at the same time. 

With some luck, the Electrical Demons will be gone.

All Pete, thank you for your efforts as well! 

Cuda Ken, hope to be done with doing dumb shit things again!

[ws23rt]

There is never a period where we don't do dumb shit things   There is just a narrow time in mid life that we do fewer.

[cudaken]