Diagnosing a no start. 5.5 volts at coil. My coil is original style with 5203R marked on side. Do these coils have internal resistor? When I got the car, running fine. I notice now they had both wires on same terminal at the resistor on inside firewall. Thought switch could still be issue so I put jumper from coil to battery. Still no start. Bad coil? Resistance measurements of coil seem ok. Condenser??
Another Coil Question
- Thread starter GAR64
- Start date
Phil Gillespie
Well-known member
Presume its a 6v coil. Normally through a resistor you will be seeing 3,5v at the coil. Coil resistance is approx 1.8 ohms primary and 8 to 9 kohms secondary.
Is it a round type coil or the original type coil.
Phil NZ
JSeery
Member Emeritus
If it has been run for a while with the resistor by-passed it may have damaged the coil. All coils have internal resistance, The original Ford coils are designed to work with an external ballast resistor. If you were using a "can" coil of 3.5 ohms resistance, it would not use an additional external resistor.
JSeery
Member Emeritus
I would start with the coil. Would consider sending it out to get it rebuilt. Fairly quick turnaround normally I believe.
Sounds like you are already getting too much voltage to the coil, so don't see how any jumper wires are going to help. Other issues could be the distributor/points.
Sounds like you are already getting too much voltage to the coil, so don't see how any jumper wires are going to help. Other issues could be the distributor/points.
Lawson Cox
Well-known member
Yeah. Send coil to Skip Haney in Punta Gorda, FL to be rebuilt. Fantastic work and turn around.
Tinker
Well-known member
It might have started better and ran well for short trips. But over time it is not a good thing for an old coil. Skip crew is a great suggestion and you'll have a better coil then you can buy anywhere. Btw don't ever leave the ignition switch on without the motor running less you like to gamble.
If you want a momentary 6volts to the coil on startup (and you don't care about making a points only vehicle) you can use a 4pole solenoid from a old ford 6v tractor. Or make up a diode jumper. 4 pole is easier though.
https://www.steinertractor.com/ABC3...EICNKhvrzl-Q4U2BaJDiQKRFr5f2opmxoC97gQAvD_BwE
TerryOH
Well-known member
If the resistor is not used, you should have battery voltage on the coil not 5.5V unless your batter is very low on charge. check the voltage on the coil while turning the engine over, if it decreases charge the battery and take it to the auto parts store to have it checked. What year is your car? Original coils are not marked on the side, so find an original and have it rebuilt or contact Skip and see if he has a nice original core to rebuild. Skip can also supply a good condenser.
Car is a 47. Sounds like easier starting if sending more voltage to coil but over time, not a good thing. I did resistance tests on coil and got lowT 0.7 and HighT 8400. I’m going to replace condenser first before rebuilding the coil. Thanks for info on rebuild. I’ll contact him.
Tinker
Well-known member
Do that and connect the underdash resistor. You don't want 5-6v at the coil less it's built for it. 3.5-4v at the coil. Pretty sure skip can wind you one if you want without resistor. Even a 12v version.
On a 47 you could run a 57 can coil theoretically.
rotorwrench
Well-known member
A 1.5 Ohm primary "can" type coil can run with out a ballast on 6-volt systems. The Mallory design coil that was used by Ford and some aftermarket OEM type bakelite coils generally need the OEM ballast resistor due to the design difference of this type coil.
A 3 Ohm can type coil would be for 12-volt stand alone systems with no ballast. The 1.5 Ohm can type coils would need a 1.3 to 1.5 Ohm ballast resistor to run on 12-volts.
A 3 Ohm can type coil would be for 12-volt stand alone systems with no ballast. The 1.5 Ohm can type coils would need a 1.3 to 1.5 Ohm ballast resistor to run on 12-volts.