Ballist resister question

[383MovingViolation]

What is the correct ballist resister ohm rating for a 1966 Plymouth Satellite w/ 383 engine? Does a 1.25 ohm seem right? Thanks

 

[Meep-Meep]

That's a good question so I grabbed the 68 FSM to have a look (should be about the same as 66).

Ballast resistor resistance at 70-80 deg F: .5 to .6 Ohms
Coil primary resistance at 70-80 deg F: 1.65-1.79 Ohms
Current draw (coil and ballast resistor in circuit): Engine stopped 3.0 Amps. Engine idling 1.9 Amps.

I will note if your coil has very low resistance like .5 or so you can use the 1.25 Ohm resistor. Seems the total resistance in the factory circuit is about 2.25 Ohms to get 9V at the coil when the engine is running (based on a 3A load).

 

[383MovingViolation]

Thanks Mr Meep-Meep. I have a 1.25 ohm in the car right now but I don't know if it's ever been replaced. I wanted to buy a spare so that if something happens and it stops working, I'll have a backup and won't be "dead in the water". Thanks, Richard

 

[b-star69]

i allways keep one in the glovebox

 

[Pops1967GTX]

Question: Back in the Day, didn't racers use lower Ballast ohms values to increase spark for better Horsepower ..Coil life would be lowered....

 

[Meep-Meep]

I never heard of that but increasing the voltage to the coil will definitely increase it's output so it makes sense.

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I have heard of putting a piece of vacuum hose behind the movable points contact arm to increase spring tension and keep it from bouncing.