1955 ignition coil issue

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sylvurhfox

sylvurhfox

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Apr 28, 2020
Thunderbird Year
1955
I just recently put my 55 back on the road. I rewired the car completely, except for the battery cables. I still run the 6V positive ground system. Before tearing the car apart I ran it for many years with the same coil. Since putting the car back together I have went through 4 or 5 coils. I get about 500 miles and the coil fails. The car starts and runs, but when driving as the speed increases and the RPMs go up the engine starts to cut out. If I maintain a RPM level about 1500-1700 Rpms I can make it home. I change the coil and I have no issues driving for 400 and more miles. Then again at about 500 miles the coil fails again. I have replaced the Points, Condenser, rotor and cap but I still get the same results, the coil fails. I have been using the 6V Blue Streak coils. I have also tried an NGK coil with the same results. I have checked and found no power at the coil until the ignition switch is turned on so the coil is not powered all the time. Any suggestions?
 
Check the other remarks on the 1957 Hot coil post from valhalla 4771. References are made about the ballast resistor and one reply noted a voltage reducer. I had a ballast resistor go out in a 67 mopar and the car quit flat out. They are funny. You may want to consider the pertronix system too. I am still running 6V +gnd and conventional ignition but have only replaced one coil since 55.
 
A 6V system should not have a ballast resistor. If you had power to the coil with the ignition off the car would not shut off. 6 volt coil failures are not common, I have to think a little more...
 
2 Ideas....
1. Make sure the coil is secured firmly. Vibration will cause the windings to separate and the coil to fail.
2. Check the ignition wire from the coil to the distributor cap. Thinking the connection (boot) on either end is loose or the metal connecctor is working its way out of the coil thru engine vibration. Are the contacts on the wire clean and making a full and firm connection into the coil snout?
 
You said that you rewired the car completely and since putting the car back together you have gone through 4 or 5 coils. Since your car is still 6 volt positive ground do you have the wire that comes from the ignition switch connected to the coil's negative terminal and the wire going to the distributor connected to the coil's positive terminal?

Did you perform a resistance test on the 4 or 5 coils that you replaced to see if the primary or secondary windings have failed? At 75 degrees, the primary resistance should be between 1.05 to 1.15 ohms and the secondary resistance should be 4,100 ohms.

doug7740
1955 Thunderbird Blue
 
Thanks for all the responses. The coil is tight in the holder and the coil wire terminals are tight and clean. I was told the wire from the key swicth is to go to the positive terminal on the coil. Is that wrong? That could be the reason for coil failures.
 
Oh, and by the way I did not check the replaced coils. I don't know how to perform that test. But I do have an ohm meter.
 
Because of you 'bird having a Positive Ground the key switch goes to the - side of the coil and the, distributor goes to the + side of the coil.
(Negative Ground cars have the key switch going to the + side of the coil and the distributor to the - side)

Did you replace the wires going to the + and - terminals of the coil with the same gauge wire?
In particular the wire from your key switch to the + side, of the coil, if its too small could cause an amp issue. (?)

Following up on Doug7740's comment; Zero out your ohm meter and put one lead on the + and one lead on the - terminals.
Do Not Touch the coil output terminal taking this measurement, depending on the condition of the coil you could get shocked.
Look for Doug's Primary resistance.
To test the Secondary put one lead on the + side and the other lead in to the Coil output, again look for Doug's Secondary resistance
 
sylvurhfox said:
I just recently put my 55 back on the road. I rewired the car completely, except for the battery cables. I still run the 6V positive ground system. Before tearing the car apart I ran it for many years with the same coil. Since putting the car back together I have went through 4 or 5 coils. I get about 500 miles and the coil fails. The car starts and runs, but when driving as the speed increases and the RPMs go up the engine starts to cut out. If I maintain a RPM level about 1500-1700 Rpms I can make it home. I change the coil and I have no issues driving for 400 and more miles. Then again at about 500 miles the coil fails again. I have replaced the Points, Condenser, rotor and cap but I still get the same results, the coil fails. I have been using the 6V Blue Streak coils. I have also tried an NGK coil with the same results. I have checked and found no power at the coil until the ignition switch is turned on so the coil is not powered all the time. Any suggestions?
Click to expand...
 
sylvurhfox said:
I just recently put my 55 back on the road. I rewired the car completely, except for the battery cables. I still run the 6V positive ground system. Before tearing the car apart I ran it for many years with the same coil. Since putting the car back together I have went through 4 or 5 coils. I get about 500 miles and the coil fails. The car starts and runs, but when driving as the speed increases and the RPMs go up the engine starts to cut out. If I maintain a RPM level about 1500-1700 Rpms I can make it home. I change the coil and I have no issues driving for 400 and more miles. Then again at about 500 miles the coil fails again. I have replaced the Points, Condenser, rotor and cap but I still get the same results, the coil fails. I have been using the 6V Blue Streak coils. I have also tried an NGK coil with the same results. I have checked and found no power at the coil until the ignition switch is turned on so the coil is not powered all the time. Any suggestions?
Click to expand...
sylvurhfox said:
Thanks for all the responses. The coil is tight in the holder and the coil wire terminals are tight and clean. I was told the wire from the key swicth is to go to the positive terminal on the coil. Is that wrong? That could be the reason for coil failures.
Click to expand...
As with the defective off-shore made mechanical fuel pumps, just because an ignition coil is new doesn't necessarily mean it's any good.
Although going thru several coils does tend to point to another problem???

Since you're using the original Positive ground setup... the Plus (+) terminal on the coil should go to the distributor / points.

Make sure the Ground wire for the points is in good shape and well connected. It can easily fail from 65+ years of being flexed as the distributor parts move back & forth.
.
 

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sylvurhfox said:
I just recently put my 55 back on the road. I rewired the car completely, except for the battery cables. I still run the 6V positive ground system. Before tearing the car apart I ran it for many years with the same coil. Since putting the car back together I have went through 4 or 5 coils. I get about 500 miles and the coil fails. The car starts and runs, but when driving as the speed increases and the RPMs go up the engine starts to cut out. If I maintain a RPM level about 1500-1700 Rpms I can make it home. I change the coil and I have no issues driving for 400 and more miles. Then again at about 500 miles the coil fails again. I have replaced the Points, Condenser, rotor and cap but I still get the same results, the coil fails. I have been using the 6V Blue Streak coils. I have also tried an NGK coil with the same results. I have checked and found no power at the coil until the ignition switch is turned on so the coil is not powered all the time. Any suggestions?
Click to expand...
Don’t overlook your regulator out put, could be a little to “hot” for the coil.
 
Ive had the same coil for 30 years so I ordered a new one! Also I discovered that I didnt have a carb screen so will install one as well...thx!
 
Chatrat said:
Ive had the same coil for 30 years so I ordered a new one! Also I discovered that I didnt have a carb screen so will install one as well...thx!
Click to expand...
30yrs is a long time. They are a large capacitor and they will eventually dry out and cant be rejuvenated past a certain point.
 
Also had my fuel pump rebuilt and installed an electric inline pump...now starts like a dream! Juat got to get her going over 2000 rpms...
 
sylvurhfox said:
I just recently put my 55 back on the road. I rewired the car completely, except for the battery cables. I still run the 6V positive ground system. Before tearing the car apart I ran it for many years with the same coil. Since putting the car back together I have went through 4 or 5 coils. I get about 500 miles and the coil fails. The car starts and runs, but when driving as the speed increases and the RPMs go up the engine starts to cut out. If I maintain a RPM level about 1500-1700 Rpms I can make it home. I change the coil and I have no issues driving for 400 and more miles. Then again at about 500 miles the coil fails again. I have replaced the Points, Condenser, rotor and cap but I still get the same results, the coil fails. I have been using the 6V Blue Streak coils. I have also tried an NGK coil with the same results. I have checked and found no power at the coil until the ignition switch is turned on so the coil is not powered all the time. Any suggestions?
Click to expand...
I am starting to go thru coils too. What did you finally settle on?
 
I got a new 6V coil and wired the key to the negative terminal. I have not had an issue since.
 
Unless you are running Pertronics.
 
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