Ballast bypass tryout

[beanhead]

So I did it, okay fine, 12 volts at the coil in 'run'. No noticeable difference....EXCEPT my tach (AutoMeter) stopped working right...well, it worked 'backwards'. At idle, the needle read properly, but with any throttle increase the needle would go back toward zero, like some sort of polarity reversal. If I quickly goosed the gas it would quickly peg to zero....anyone know what's up with that? I put the resistor back and it returned to proper operation. (The tach runs off of the coil (-) terminal btw.)

 

[Joe66satellite]

So I did it, okay fine, 12 volts at the coil in 'run'. No noticeable difference....EXCEPT my tach (AutoMeter) stopped working right...well, it worked 'backwards'. At idle, the needle read properly, but with any throttle increase the needle would go back toward zero, like some sort of polarity reversal. If I quickly goosed the gas it would quickly peg to zero....anyone know what's up with that? I put the resistor back and it returned to proper operation. (The tach runs off of the coil (-) terminal btw.)

What do you have for an ignition system

 

[beanhead]

Mopar chrome ECU and a firecore stock-type distributor.

 

[Demonic]

I don't believe you can bypass a ballast with a Chrome box a stock type coil.

 

[Smokinnjokin]

It will work, just overheat the coil and burn it out prematurely.

 

[beanhead]

That's what I've always heard too, or it protects the ECU. However, lots of people run without one and don't burn the coil up... According to Chrysler the resistor was there to protect the contacts in the old points and then the early controllers. No physical contacts making and breaking anymore though...I still tend to think if a coil mfr. says to use a resistor(like msd) then you should. But, I am trying to track down a rough idle issue and it was really just a test to see if a higher coil hit would fix the issue (it didn't)..the tach running backwards is what has me scratching my head...

 

[SureGrip]

I always thought the tach ran off the + side of the coil.

 

[khryslerkid]

https://itstillruns.com/wire-autometer-tach-5877262.html

https://www.forbbodiesonly.com/mopa...r-street-tach-install-wiring-questions.16281/