Checking an Ignition Ballast Resistor

[FlatheadTed]

Some can type coils state resister needed but thats for 12 volt ,remove the resister and its suitable for 6 volt ,but check the ohms ,you
may find the old school condenser is more reliable than some repoped ones ,some shrink tube , did you check if there was a spark across the plug ,Sound Fuel related to me ,

[Jeff/Illinois]

Originally Posted by JSeery

Is there some confusion here? Voltage to a 1.5 ohm coil should be full system voltage, 6+ volts. You may be thinking of the voltage to an original distributor mounted coil.

I have never checked it, but the claim is reversing polarity at the coil results in about 80% loss of coil output. For a positive ground vehicle it should be supply voltage from the ignition switch connects to the (-) terminal and the (+) terminal connects to the distributor (points/capacitor).

Today I had the time to by-pass the resistor under the dash, and did as you said, moving the ignition switch to resistor wire over to the 'out' side of the resistor so it follows the red wire directly to the neg. post on the coil now. Can type coil internal resistor measures 1.5 ohms at the coil.

I have 6.1V at the ignition switch and 5.9V at the negative post on the coil. I just don't seem to be getting anything out of the distributor. I'm figuring the points have arced or burned or something. The '36 started sputtering losing power, came out of it got about 2 miles and then quietly shut down.

First thing I thought of was fuel, the accelerator pump is working I'm getting gas to the carb, first thing I did when I got home was dribble a little gasoline in the carb and still couldn't get it to pop. This is on a Stromberg 97 that had a rebuild 2-3 years ago from a very very reputable guy, a Stromberg guru.

Anyway I'm more of a Model A guy flatheads are still new to me. When a Model A acts like this '36 did, it is points closing up about 90% of the time that is real common. Even a weak condensor on a Model A Ford will give you some power at the engine, just makes the A run weak. I just guess I'm prejudiced in that way of thinking, been around Model A's since 1971.

I hold the coil wire to ground and my wife cranks it and there is no spark. Put a new NAPA FA 54 condensor on no change (didn't have the facilities to have that condensor checked possible it is bad out of the box, Made in Mexico usually there stuff is pretty decent.)

Nothing wrong with the starting circuit this truck cranks like a new car really turns over.

I am going to call Jim at Bubba's and speak with him, after that I will get back on here and let you all know what happened. It has to be something simple I'll keep picking at it. I've never changed points on a flathead distributor, I am assuming you have to set them up on a Sun machine.

Thanks to all for the help and advice, it's greatly appreciated I'll be back..........

[JSeery]

Hang in there.

[JayChicago]

Your 4.2 volts on the distributor side of the coil makes me think there is resistance between the coil and where it goes to ground at the points. You could try this simple step before having to get into the distributor:

Your can type coil uses an aftermarket adapter on top of the distributor where the original coil was mounted. Adapter is easily removed. See if anything obviously wrong with the adapter. Remove the small wire coming from coil and clean that connection. Also clean the contacts on the underside of adapter where they make electrical contact inside the distributor. While you have it off, put your ohmmeter to it. Should get no reading (full continuity) thru the adapter.

[Jeff/Illinois]

Originally Posted by JSeery

Hang in there.

Thanks bud, electronic ignition may be the way to go I'll read up more on that. Comments by people are good and bad like anything else. I've had a Pertronix on my '69 Mach 1 for probably 15 years and never ever had an issue. I HAVE read in Early V-8 stories of the front mounted dist. being kind of troublesome and it cost consumers back in the old days a bit of trouble and expense. Of course they had to wait until Henry died to change it out to a more modern type that we see in post 1948 flatheads.

Jay thanks for your suggestion I will give that a try too!

I'll let the Forum know what I find out again thanks for the help

[JSeery]

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I know very little about Pertronix use in flatheads, but understand they work OK with 12v systems but not so well on 6v.

[rotorwrench]

The front mounted distributor doesn't make it easy to troubleshoot on the early V8s thru 1948. The crab type maybe but the Helmet type not so much unless a person removes it and inspects the parts in there on the bench. A bad condenser can completely kill the inductance of the coil and not allow any spark at all. It just depends on the condition of it. Don't assume that it will still function an any usable capacity. Just replace it with a known to be good part and check for good spark. If the points are burned up then that would be a good indication that the condenser is/was bad since that's what protects the points from arcing. Many of the new replacement condensers are crap right out of the box. Setting up the helmet isn't too bad. A person just has to follow the Ford instructions. The condition of the flyweights, vacuum brake, and the rotor & cap parts can all be scrutinized & repaired as needed. If the ignition leads are very old and in poor condition, it might not be a bad idea to replace them. These units need maintenance & lubrication now and then to insure it all still works as it should. If the timing was already pretty close, the chances are pretty good that it will remain that way. Bolt the thing back on and test it.

Electronic ignition may be an alternative but a well maintained original system will give years of trouble free service on cars that are stored well and operated regularly. Echlin condensers are still decent parts when compared to a lot of others but they recently merged with Standard Motor Parts so the quality may be in question from what they used to be. The high dollar Vertex magneto condensers are out there but they aren't set up well for the helmet design distributor.

As I mentioned before, those can coil adapters can go to crap on you and it should be checked for contact and fit. The helmets work a lot better with their original coil installed but there were several different coils available in 1936 so it depends on which one will fit as to how easy it would be to find a good core to rebuild.

[Jeff/Illinois]

Originally Posted by JSeery

I know very little about Pertronix use in flatheads, but understand they work OK with 12v systems but not so well on 6v.

I never thought of that. Looks like since I'm just staying with 6V POS ground as original I'll go back down that path.

Rotorwrench what you say makes good sense thank you