Which coil to use?

[tank1949]

My coil may have gone BAD. It says "Mercruiser" on the coil's body, but faintly. No other writing is available. It is installed on a an older 350/stroker carbureted motor using a MC TB5 ignition system. I believe a Chevy automotive internal resistor coil could work on the TB 5 but I am not 100% sure. Manual is not clear on coil required to be internal or external resistor type. In addition, should coil be HEI? Or are they all HEI?

 

[dave8311]

Coils very rarely go bad. I would troubleshoot more before throwing parts at it.

 

[Bt Doctur]

but if it did go bad, any gm coil for electronic ign will work. They have internal resisters

 

[tank1949]

Coils very rarely go bad. I would troubleshoot more before throwing parts at it.

We are. We cannot get fire out of main coil wire with helm switch on. 12 volts is coming to + side of coil. Main lead should arc between spark plug contacts but no arc. We will rotate with our stb motor's working coil to further rule out coil. Motor has set for 4 years due to my health issues. Moisture may have gotten inside.

 

[tank1949]

but if it did go bad, any gm coil for electronic ign will work. They have internal resisters

So the HEI designation is Bs?

 

[Bt Doctur]

 

[tank1949]

Thanks. I have tested about 1/3 way. Is there a difference between HEI and regular coils?

 

[Scott06]

Thanks. I have tested about 1/3 way. Is there a difference between HEI and regular coils?

Electronic ignition coils like used on HEI have an internal resistor, points type coils use an external resistor. Will have a resistance wire in Barnes or ballast resistor to lower voltage to not burn up
Points

 

[tank1949]

Electronic ignition coils like used on HEI have an internal resistor, points type coils use an external resistor. Will have a resistance wire in Barnes or ballast resistor to lower voltage to not burn up
Points

I had forgotten that. I had a senior moment! THX