Voltage to coil on 39 Ford

JSeery...I am using a standard modern round coil, NAPA type, mounted on inner fender.
There is no starter solenoid as it is a foot starter type.
When you say there should be no resistor when using the modern NAPA round coil, do I disconect the red coil wire at the under dash resistor and install it to the iginition switch ?
My battery reads 6.58 volts....I do not have the ristor reading at this moment but can obtain it if needed...I am hoping that the problem of no start is due to the resistor being hooked up when it is not needed....What do you think ????
 
That is most likely your problem. The can coils do not use a ballast resistor on 6v. An easy wiring correction would be to move the wire from one end of the ballast resistor to the other so the wire from the ignition switch and the wire to the coil are on the same terminal. There may be additional issues here. If you are measuring 6.58v at the battery then it should be right at the same value into the ignition switch and only slightly less out of the ignition switch. You should be getting 6v or a little more to the coil.
 
If you have by passed the resister and have 6 volts for coil ,the coil I show is a 6 volt
for 49 to 55 #IC8 round. Once hooked up take the coil wire and hold 1/4 the grd and turning engine over see if spark jumps 1/4". NO Spark Points or condenser.
Pos would be Ground on coil.
 
3.7 volts is to low ,As has been said likely the resister ,if its a stock Ford one some times there is restance in the connections GM posted about soldering the Nick chrome wire some time back .the naper tube coil with fawn colour top (6volt ) doesn't need a resister, Current draw at idol is around about 3 volts .Ted
 
I have removed the coil wire from the left hand side of the resistor and moved it to the right side of the resistor with the iginition wire.I now have the following.
I have 6.58 volts at the ignition in off position
I have 5.80 with the ignition turned on.
I have 5.34 volts at the terminal on the coil that the red wire attaches to.
Do I have enough voltage "5.34" at the coil to start the car ????????
Do these voltage drops seem excessive ?????
 
Yes 5.34.is ok
If the wire is not attached to the coil it should be closer to 6 volt,I think the voltages are ok ,Others may differ ,Ted
 
Last edited:
Just tried to start the car and it did not start and I believe it is related to the starter turning the engine over too slow.
All grounds have been cleaned to bare metal and an extra ground added from starter to frame. My new battery is fully charged 6.58 volts.
Even tho the starter test ok resistance wise, at least according to the shop who tested it, They said they had no way of putting a load on it when testing it.
Do other shops have a way to test it under a load ?
 
Not sure what battery you are running...just make sure you have enough CCA rating.
Trying to start a flathead with one of them small 6v battery´s for beetles ends up barely turning the engine over.
 
As others have stated, 5.34 volts at the coil should be enough to fire the engine. But that is way to much voltage drop through the ignition switch. There are several possible issues here.

1. Starter is not turning the engine over fast enough.
2. Ignition switch has excessive resistance and needs to have the contacts cleaned.
3. Assuming the 5.34 volts at the coil is without the starting turning, the voltage will drop well below this when you start cranking the engine over.

With the starting turning slow and the voltage most likely dropping well below 5v it will be difficult to get it to fire.

Couple of testing ideas.

1. Run a jumper wire with alligator clips straight from the battery or starter floor switch to the coil. This should give you full battery voltage to the coil. Do not leave this connected for more than a short period of time without the engine running. It is ok to keep it connected if the engine is running.

2. Try jumping the starter with a 12v battery and see if that spins the engine. You need to make sure the 6v battery is disconnected or isolated from the starter when you do this. I would also isolate it from the reset of the car wiring. An easy way to do this would be to disconnect the wire from the starter switch to the starter and then jump the 12v battery directly to the starter.
 
Last edited:
I will remove the ignition switch to clean the contacts. I presume the contacts are inside the switch. Does it come apart easily to get to the contacts ?
 
If you measure from battery to starter with a voltmeter while cranking you get a reading of the voltagedrop in the wiring and switch...then you can start to narrow it down by measuring over individual wires and the switch...that should tell you where the problem is.
 
JSeery....ran a jumper from my 6 volt battery to coil where red wire attaches to the post. No difference in starter performance.
Then I used a 12v battery directly to starter with everything else unhooked and it did not turn over any faster than with 6 volts.
So at this point it appears to be the starter....so I have a few questions on options.
1...have this starter rebuilt if parts are available ?
2...buy a new starter from a vendor ?
3...try to find a modern high torque starter for a 6 volt ?
What do you guys think ????
 
If the car has not run for 9 years, I would remove the plugs and oil the cylinder's
Turns over with 12 volts see if gets any faster. I hope you are using a known 6 volt coil. Check for spark out the coil wire, also maybe mount coil on engine closer to dist.
 
George...i have already pulled the plugs and oiled the cylinders several times so everything is free and I turned the engine over easily by hand.
I removed the old coil and put in a new 6v coil and I do get spark out of the coil wire but still no start. The only thing I can think of is that the starter will not turn fast enough to get the engine to fire...but...who knows, it could be something else.
The coil is mounted to the inner fender approx 18" from the distributor.
I did try to turn over the engine with a 12v battery hooked directly to the starter and it did not tun over any faster than using the 6v battery....that why I am leaning to a bad starter as the problem....I do not know how to test the starter under load. I have bench tested it without a load and it turns over nicely. Trying to get opinions on what to do about my starter....See my last post.....thanks for your input..
 
Anyone have any suggestions on wether I should have my old starter rebuilt or buy another one from a vendor ?
also what about the high torque starters, are they available for a 1947-48, 59A/B engine and is it even nescessary to have a high torque starter for this engine ?
 
You must log in or register to reply here.
Back
Top