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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16209
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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On the shift interupter switch.. (alpha one) i understand

Customer Question

hi there.. on the shift interupter switch.. (alpha one) i understand that this switch momentarily grounds the coil therefore killing spark. but question i have is what exactly does it ground to on the coil?? is it the fire wire or what is it? just doing some rewiring and this has me confused
Submitted: 2 months ago.
Category: Boat
Expert:  Jason replied 2 months ago.

H​ello my name is ***** ***** am I speaking with? I read what you wrote. The shift interrupt switch actually does different things and it depends on which specific ignition system you have on the engine. Do you know which ignition system you have? If not, do you have the serial number on the engine so I can ID the motor.

Customer: replied 2 months ago.
my name is Ken.. it has a high energy ignition system.
Expert:  Jason replied 2 months ago.

Hi Ken. Is it a Thunderbolt system?

Customer: replied 2 months ago.
I dont know what kind it is. it's had a HEI dizzy put on it and the interupter switch isnt hooked up to it.. the HEI has the coil in the cap. its an all-in-one distributer.
Expert:  Jason replied 2 months ago.

That would be an automotive distributor, not a marine one. Any idea why it has an automotive distributor on it?

Customer: replied 2 months ago.
Better system maybe? do interupter switches not work with these?
Expert:  Jason replied 2 months ago.

Honestly I don't know. I would never use an automotive distributor in a boat, it is illegal to do so. Whenever I come across engines that do have them installed in the boat I tell customers that they are illegal, and I will not work on the unless unless either I or the customer changes that distributor to a correct marine distributor.

Customer: replied 2 months ago.
Expert:  Jason replied 2 months ago.

Yes. I'm on the phone with another customer at the moment but I will be back as shortly as I can.

Expert:  Jason replied 2 months ago.

Okay I am back. Electrical components on a marine engine, such as the starter, alternator, distributor ect all have to be what is called "ignition protected". Ignition protected means that if there was a fume build up in the boat that these components could not possibly cause a spark and ignite those fumes. If you get caught running an automotive distributor in a boat during a safety inspection you would be given a hefty fine as well as a tow back to port, as the Coast guard will not let the engine be run with that distributor in it. If you were to ever have an accident/fire/explosion, and the insurance company finds out you have an automotive distributor, they would cancel your insurance policy. Does that all make sense.