coil resitor bypass

R2W55

R2W55

Junior Member
I am wondering if any of you have experienced this problem with the coil and external resistor. For reference it is on a 1940 Pickup, 6v pos gnd.
I replaced the resistor with one from MACs and really have not had a problem.
Because of an occasional 'Hard Start" I added a bypass switch across the resistor to short it out and give a hotter spark. Seems to help those occasional times.
I was driving the other day and the engine starting hesitating. After trying a few other things, I flipped the switch, shorting out the resistor, and the engine smoothed out. After about 4-5 seconds running this way I turned off the switch and was fine.
The next day I changed the coil and the same thing happened with the same results turning on/off the switch.
I also have an aux, fuel pump (in case of a vapor lock) but turning this on didn't change the hesitation so not fuel.
Any ideas what this could be? and how to fix?
 
Not a bad idea but why would it 'recover' after a few seconds hotter coil voltage?
It's actually a fairly new capacitor (less than 100 miles) but I have had them go bad quickly. Probably wouldn't hurt to swap it out also.
 
I just experienced the same thing last Sunday. Driving along on a return trip about 30 miles from home and the car (59A) engine started hesitating and stumbling creating a "bucking" effect. We limped the car home slowly. At first I suspected vapor lock and flipped on my electric pump but this had no effect on the engine. A couple of times the engine did die but when it did it would restart immediately so I don't think it is a coil, although I haven't ruled that out. I soon suspected ignition related problems such as a condenser (capacitor). Monday I picked up a new condenser from NAPA and installed it. I have not yet tested the car under load. It did start right up and idle fine and I shut it off as it was dark and raining by this time. I will let you know the results of the road test as soon as I can get to it.
 
Great minds think a like!
Maybe it was the Eclipse effect?
Looking forward to your results.
_____________________________
I need to get this resolved as I have the 40 pickup for sale and don't want it to happen to a perspective buyer!
 
I rebuilt a distributor for a 39, it ran for a short time then started running bad, along with the smell of burning bamboo-- the "macs" resistor lost its connections because the ends were just screwed to the bamboo--- originals are ceramic and riveted----- I installed a used original-- no more problems
 
Kurt in NJ said:
I rebuilt a distributor for a 39, it ran for a short time then started running bad, along with the smell of burning bamboo-- the "macs" resistor lost its connections because the ends were just screwed to the bamboo--- originals are ceramic and riveted----- I installed a used original-- no more problems
Click to expand...

Solder the ends of the original resistor. Look up details on recent post.
G.M.
 
Well just to add another idea to the mix, I had the same problem in my 38 pickup (59A with crab distributor) last Friday. Stopped completely at one stage but restarted after a few minutes but stumbled home.
Tried replacing all the usual, coil, condenser, and then I swapped distributors, still the same.
Turned out to be the rotor which I had swapped between distributors. It was a dud earthing in the centre. Swapped it and bingo! No more stumbling when hot ( well so far).
So you learn something else all the time.
Dave
 
Last week when driving the 35, after 30 miles or so flathead started missing.Replaced condensor after 30 miles miss was back.Replaced coil next day car runs a raped ape again.Stock 221 411 rear 70 mph and still had a little more.Mostly run it 55 -60 .I don't like to abuse it.Sent a core Skip today .
 
Check the ignition switch . Remove it and check the contacts inside. If they are burned or dirty it's causing a high resistance.
 
All good ideas and solutions but I'm still confused why the problem went away after shorting the resistor out for only 3-4 seconds . It couldn't have cooled off that fast and then it would have reheated and the problem return. I'm going to look at the resistor closer and replace the capacitor. Maybe I'll find a bad connection.
1940 Pickup still for sale. I'm reducing price to $20K (negotiable)
 
R2W55 said:
I am wondering if any of you have experienced this problem with the coil and external resistor. For reference it is on a 1940 Pickup, 6v pos gnd.
I replaced the resistor with one from MACs and really have not had a problem.
Because of an occasional 'Hard Start" I added a bypass switch across the resistor to short it out and give a hotter spark. Seems to help those occasional times.
I was driving the other day and the engine starting hesitating. After trying a few other things, I flipped the switch, shorting out the resistor, and the engine smoothed out. After about 4-5 seconds running this way I turned off the switch and was fine.
The next day I changed the coil and the same thing happened with the same results turning on/off the switch.
I also have an aux, fuel pump (in case of a vapor lock) but turning this on didn't change the hesitation so not fuel.
Any ideas what this could be? and how to fix?
Click to expand...

I've read all of your posts and might suggest your voltage is falling below what is necessary to keep the spark "hot" and subsequently, the engine running well.
I know it sounds like a long shot but have you checked the voltage at the distributor when you are having this issue?
 
Our son, daughter in law, and new little grandson live on Woodstock street in Crystal Lake. I had the thought I should buy your truck and leave it at their house for when we come out to visit. Wife did not think that was a good idea...darn.
 
I have a Alternator and the digital meter under the dash is about 7V.
But I think I will run some leads to the coil so can monitor the coil voltage while driving.
that should answer that question. Great suggestion.
 
If bypassing the ballast resistor "evened out" the problem, it is likely that there is a voltage drop between the battery and ignition switch, the resistor, and the coil input somewhere. I'd bet on the ignition switch, as the "wiper" chews a groove in the Bakelite that holds the contacts. When you use your bypass switch, it rises the system voltage to bridge the problem. To test for voltage drop, use a voltmeter. If you don't have one, but the cheapest analog type you can find, and place the probes across each portion of the circuit. Any reading shows how much loss there is in that place. I carry a cheap meter in my "road kit" as a useful diagnostic tool. I recently found a bad connection between the battery cable and the starter solenoid connection where all the vehicle is powered. The connection was causing all the symptoms of the dreaded "vapor lock"!
 
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