Wiring engine converted ignition

[wayoutthere]

Thanks in advance for any and all help.

so this 79 ski nautique im rebuilding has what looks to be the original distributor with an electric ignition kit added on.
Every wire at the engine has been cut and the wires that clearly look like they were attached to the white plastic box (ignition/ ballast/ resistor) thing on the back of the engine are connected together.

I want to start gathering up materials so i can make a nice engine harness , an old style mercruiser engine harness kit is what im thinking so the wires dont have to be cut if the engine has to come back out or if and when it comes time for a swap.

big question is how to wire the ignition now that its been converted? what else should i change on this engine?
it needs all new gauges so the boat gets a new harness as well.

where can i get a key, the ignition switch is nice but key is long gone.

I can get some pics if that would help
thanks

[hal2814]

The answer is “it depends.” That white plastic box is a ballast resistor. When your boat was new, a purple wire ran from the ignition key to that ballast resistor to the coil and to the distributor. That resistor knocks voltage down for the coil and for the points and condenser in the distributor. The distributor only had a single wire running to it. It grounded to the plate under the rotor. It’s a very simple, elegant system that does require occasional maintenance.

Electronic distributors work differently. They usually run at a full 12V. They also require a separate ground hookup (most people use the alternator’s ground since it’s right there). So the distributor itself usually (almost always) has to bypass that resistor. The worst part about it is that it’ll fire up cold through the resistor. It‘ll act up just long enough after running to strand you somewhere. Then there’s the coil. The coil typically still uses the voltage from the resistor. So now you need two wires: one for the distributor bypassing the resistor and one for the coil through the resistor. BUT some people has changed out their coil for one that runs at a full 12V so you can bypass the resistor entirely and have wiring that looks closer to factory but with a bypassed resistor and new ground wire. Again, if the coil is set up wrong it’ll usually run fine cold. You’ll get hot start issues.

With knowing specifically which electronic unit you have and which coil you have, it’s not possible to know the correct wiring. There is also not a great way to diagnose the correct wiring due to issues only cropping up after the engine has been running for a while.

[wayoutthere]

Thank you,
i'll have to open up the crate that the engine is in and post a photo.
there is no wires on the ballast resistor but 2 purples are spliced together right there, and can't remember whats on the coil.
starting from scratch from the sensors to the dash with the harness on this one and it needs a starter, you know how it goes,
what doesnt it need is the shorter list

[wayoutthere]

So the wire to and from the ballast resistor are spliced. Somebody "wired up" this thing under machine gun fire by the looks of it and i would rather know nothing is jumped over or some other magical electrician sparky trick to make it run.

it needs a starter, i want to get a coil and maybe an alternator. As mentioned it was converted to electronic ignition.

i need a source for the parts and a wiring diagram for the ignition circuit.
Since it was converted to electric ignition that has me confused, and an amp meter that makes think there was some magical sparky trick to make it work.

thank you

[hal2814]

Here’s a Pertronix setup. Odds are that’s the electronic ignition unit you have. It’s the most popular. But there are others. You wiring depends on what kind of coil you want to get. You can get one that runs at full voltage and leave the ballast resistor out of the loop entirely. It’s probably what I’d do if I were relaxing the coil and the wiring were already bypassing the resistor. Based on what I see there, I’d wager the PO ran the ignition module and coil through the ballast resistor, had issues, bypassed it, and ended up with fewer issues.

[wayoutthere]

I really appreciate such a fast response and the time and detail it took and you went into.

yes i defineately want to completely remove the ballast resistor, i will open up the loom and take the cap off to photograph how it's wired and maybe the electric conversiom kit could be identified as well.

I'll be building from scratch engine and boat harnesses so in the interests of keeping it clean whateverever coil it needs and/or alternator it may need is in my opinion the way to go.

thank you

[hal2814]

You may be able to buy a new harness still. I’d call around to some places like skidim and nautiqueparts and ask. It would be a lot easier than making one.

[wayoutthere]

Understood, but i have all color coded wire, shrink connectors, special crimping tool, real nice woven loom and enjoy the diy process of trying to make everything correct, nice and pretty. The diy part is to me is the same as actually using the boat. All the supplies are leftover from the last project. Ideally this boat will be as nice in my opinion as the last one turned out.


again not everyones cup of tea but i enjoy the process.

[wayoutthere]

I'll try to explain how it has been wired in order of the pictures

yel w/red spliced into whi w/red to nuetral safe to s side of solenoid
and red to circuit breaker












orange from dash spliced into red which goes to alt.
it is spliced into orange connector melted that runs back to circuit breaker




purple from dash double spliced into red to choke and purple to batt side of coil from bat side of coil, purple to dist and purple to alt.





second last pic is ground from alternator housing that was cut and left in loom the 2 pics below the engine top pic are there on accident and cant figure how to remove.