Help - Ignition Coil Questions???

OK, I have a aftermarket coil in it and was gonna get 20amp switches so I still should be fine correct?

 

Either way I read having the coil power on its own wire and not sharing with other components is better for coil life. Also every time I've had to do work where I needed my key switched to "on" I've always unplugged my coil so it wasn't drawing the whole time. And after reading what you where saying I'm glad I was doing that.

 

I'm confused on this amp formula. Bubba used the example of a problem coil (.7 ohm coil with a 2 ohm resistor on a 12 volt) and said divide it, but came out with 32.5 amps, wouldn't it be 12 divided by 2.7 = 4.44amp ? You would multiply 2.7 x 12 to get 32.4 Am I all mixed up here?

 

Hi Bubba and friends! I have a Beru ZS106 coil. It gives 25.600v and has 3.3 omhs in the primary circuit. Non ballast resistor. My question is; Can I fit this coil with my traditional Dizzy (breaker points) without risk of burning something?
Thank you!

 

so am i under thinking this whole thing if i just run the napa coil listed without a resistor on my 41 chevy with stock points dist., and 12 volt conversion . im not a big fan of resistors . i believed with a 12 v coil on points dist they werent needed . im not sure what i have for a coil now , but the car starts and runs good , but afterabout 5 mi starts to stall and miss and makes me wonder if ill make it home . seems as if the coil is over heating and i thought i might try installing a resistor and see if that fixed it . would prefer a new coil though if that would fix it. i dont think it matters ? but the stock mtr is actually a 62 235 with the stock points dist !!

 

Don't guess!! Measure. A contact point ignition system requires about 3 ohms total resistance in the primary ignition circuit, this includes everything, the primary winding of the coil, the ignition switch, wiring, connectors, distributor to block, etc.

That's the minimum ohms resistance that will limit the total current to a safe level on a continuous basis, or stuff starts roasting. What the OEMs also did, which often confuses people, was split that 3 ohms in half to 1.5 ohms using a divider network at the starter solenoid relay.

This gives a bit hotter spark on a cold engine when the key is turned to start. When the key is turned to "run" and the engine is running then the extra ballast resistor was employed and voltage/current is reduced. Moriarty is right, the points will probably burn otherwise. Figure out what you have, measure, and Bob's Yer Uncle.

 

When I divide 12 by 2.7 I get a different number.
12V divided by 2.7 OHMS yields 4.44 AMPS, NOT 32.4 AMPS.