The Ford Barn

GAR64 · 08-07-2021, 01:49 PM

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??

Phil Gillespie · 08-07-2021, 04:12 PM

Quote:

Originally Posted by GAR64

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??

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 · 08-07-2021, 04:26 PM

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.

GAR64 · 08-07-2021, 06:19 PM

Original style coil. Cant understand why they seem to have bypassed the resistor. The guy I got the car from was very knowledgeable. Either way, any advice on diagnosis?

JSeery · 08-07-2021, 07:16 PM

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.

Lawson Cox · 08-07-2021, 08:20 PM

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Quote:

Originally Posted by JSeery

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.

Yeah. Send coil to Skip Haney in Punta Gorda, FL to be rebuilt. Fantastic work and turn around.

Tinker · 08-08-2021, 12:10 AM

Quote:

Originally Posted by GAR64

Original style coil. Cant understand why they seem to have bypassed the resistor. The guy I got the car from was very knowledgeable. Either way, any advice on diagnosis?

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/ABC39...xoC97gQAvD_BwE

Terry,OH · 08-08-2021, 06:05 AM

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.

GAR64 · 08-08-2021, 12:06 PM

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 · 08-10-2021, 12:21 AM

Quote:

Originally Posted by GAR64

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.

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 · 08-10-2021, 09:57 AM

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.

08-07-2021, 01:49 PM	#1
GAR64 Senior Member Join Date: Aug 2013 Location: Upstate NY Posts: 208	Another Coil Question 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??

08-07-2021, 04:26 PM	#3
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Another Coil Question 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.

08-07-2021, 06:19 PM	#4
GAR64 Senior Member Join Date: Aug 2013 Location: Upstate NY Posts: 208	Re: Another Coil Question Original style coil. Cant understand why they seem to have bypassed the resistor. The guy I got the car from was very knowledgeable. Either way, any advice on diagnosis?

08-07-2021, 07:16 PM	#5
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Another Coil Question 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.

08-08-2021, 06:05 AM	#8
Terry,OH Senior Member Join Date: May 2010 Posts: 4,743	Re: Another Coil Question 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.

08-08-2021, 12:06 PM	#9
GAR64 Senior Member Join Date: Aug 2013 Location: Upstate NY Posts: 208	Re: Another Coil Question 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.

08-10-2021, 09:57 AM	#11
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,425	Re: Another Coil Question 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.