1978 mercruiser 470 pertronix ignitor - coil question...

[olazabel]

i installed a pertronix ignitor (1146a) and a flamethrower 3 ohm coil on our 1978 mercruiser 470 two or three years ago. I though things were ok,

but went to start the boat yesterday and it wouldn't fire. I figured it might be the coil, so I reinstalled the original stock coil from the points system and the boat started right up.

my question now is... Can I keep the stock coil installed with the pertronix ignitor, or do I need a coil with built in (3 ohm) resistance?

I've done some reading, and I'm still not sure. I included a picture of the current wiring on the coil

Any help or explanation would be appreciated

 

[Bt Doctur]

A points coil needs to see the ballast resistor ,or resistance wire

 

[olazabel]

I read something about a resistance wire built into the harness, not sure what the two tan wires on the same ring terminal on positive side of the coil are, so I'm now wondering if I didn't need the 3 ohm coil to begin with....

am I off base, and just need to order a new 3ohm coil to replace the bad one, and put the stock coil back in the toolbox with the points?

 

[achris]

Yes you can use the original coil with the Petronix unit.

 

[KJM]

not sure about pertronix, but i just put in a hotspark electronic ignition and the instructions specifically said i need a coil with built in resistor (3 ohms). it said a lower resistance coil can cause the ignition to over heat and either shut down until it cools or even cause permanent damage and void the warranty. maybe pertronix is different but i'd make sure, if the coil they recommend is 3 ohms then i'd use 3 ohms. i got one at napa.

 

[olazabel]

thanks for the input.

I emailed pertronix, and they said they recommend a 3.0 ohm coil if the resistance wire has been removed or bypassed, and a 1.5 ohm coil if the resistance wire is still in place

I guess I'll try a 1.5 ohm coil since I did not remove or bypass the resistance wire when I installed the pertronix ignitor.

 

[trikeman72]

Hey fwiw just put one on a 2.5 gm mercruiser I have ballast resistors back on sterndrive by engine install booklet for pertronix said to NOT remove ballast resistor when installing their igniter now I did get the flame thrower coil they recommended so I'm not sure if my info helps just thought I'd share in case it is.

 

[olazabel]

Got the boat out on the water last night after installing a new 1.5 ohm coil.

It ran great while cruising, and towing a skier, but seemed like it wanted to stall when idling in the water, and did stall a couple times at low rpms while putting around, and then started to hesitate during acceleration.

My first thought was that it was carb related, because we haven't used the boat much this season, but after doing some reading, i'm wondering if this could be related to the new coil, or even cap and rotor?

I currently have the pertronix ignitor installed, and a 1.5 ohm coil because I did not remove the resistor wire from the 470 when I installed the pertronix. (which is what I think is recommended in the attached instructions from pertronix.

Any suggestions or ideas about how to rule out the carb and/or ignition system as the culprit?