Coils

[western77]

I have a model A and run the power to the coil without a resister. I also have a 53 mercury engine in a 41 ford pickup. The ignition has a resister to cut the power to the coil in half when running. My question is WHY? JB

[JSeery]

Design of the coil/ignition system. The V8 Fords were designed to use the resistance in the ignition system.

The coil used on the v8 flatheads likes to see 4 to 4.5 volts, the resister in the ignition system drops the 6 volt system (system will be greater than 6v when running) down to the 4-4.5 volt range.

[Bob C]

I don't think 49-53 used a resister.

Bob

[western77]

Bob C that is what I was wondering. I bought a new coil today and it is the same as listed for the A. The resister may have been leftover from the 41 and no one removed it?

[JSeery]

Not really up to speed on the 49 and up car, but just checked some wiring diagrams and I don't see a resistor in the ignition system after 48.

[western77]

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We'll I guess that's one less thing to do! Now if I can get the electric fuel pump to work I'll be on the road! Thank you all. JB

[JSeery]

If you want to go to the trouble you could check the resistance of the coil, you want to end up with something in the 4 amp range going to the points. Believe what some people refer to (incorrectly) as 6 volt coils are in the 1.5 ohm range. 6.25v / 1.5 ohm = 4.17A

[V8COOPMAN]

Originally Posted by JSeery

Not really up to speed on the 49 and up car, but just checked some wiring diagrams and I don't see a resistor in the ignition system after 48.

I looked too, and I couldn't find one either. Since the whole idea is to reduce the current at the points (to extend point life), and since points is essentially points, AND since we're still talking 6v, I'd almost bet that '49-'53 coil is internally resisted. I know Bubba will be along to straighten us all out. DD