Starter Coil wiring question

[BlueNote2]

Recently purchased a 1987 SeaRay for a winter project. (It is fun, but I am in it over my head!)

Has 165 470 Merc.
Switched it over to electronic ignition and adding a new coil at the same time.

I did not realize that the existing coil had external resistor, while new one just says 12 volts.

The red and black wires (not shown) coming from the electronic ignition is pretty self explanatory, but I wasn't sure about these wires that were removed from the previous coil.

Grey: Negative

Purple &
Purple w/yellow stripe: Positive

Do I need to tie-off one of these because of the new coil?


Thanks, any help is appreciated.

 

[Bt Doctur]

locate the purple with 12v at the coil, remove the other purple resistance wire and replace with standard wire(purple)

 

[BlueNote2]

BT Doc,

Thanks for quick response! Great diagram!

just to clarify...
I should : remove Purple wire, and keep Purple w/yellow stripe?

 

[Bt Doctur]

yes, the purple/yellow supplies full 12v during cranking only

 

[thumpar]

When I did my conversion I opened up the wire loom and installed a new wire inline with the existing wire to bypass the resistance wire. The old wire was taped up in case it was needed later.

 

[stonyloam]

Before we go any farther here you need to tell us which electronic ignition you have, and which coil. Petronix and Mallory are set up differently.

 

[Bt Doctur]

Hey stony, where do you live with a time zone 1 hr later than the east coast?

 

[Bt Doctur]

must be the sites posting clock, still only 8:52 in nj

 

[stonyloam]

I am on EST (near Rochester NY), but do seem to be an hour off. Let's post this and see. Yeah post is 1:38, but my iPad says 12:38. Have no idea why??? OK lets try the laptop. Same thing, I must still be on daylight savings time LOL! Do not see any way to change my time zone.

 

[BlueNote2]

@stony,

pertronix for 4cyl


(Beru coil 12v for 4 cyl- 3.3 ohms)


Layman terms please, I am new to engines. May have to bring it in to have it wired correctly if I can't figure it out.

 

[Fishermark]

Bluenote - you have the correct coil for bypassing the resistor wire. You need the full twelve volts. It is really very simple, just get the full 12v at the choke as BT Doc suggests.

On the positive side of the coil will be...
1. The purple plus yellow stripe wire from the starter.
2. The new 12v source wire you provide.
3. The red wire from the Pertronix.

On the neg side of the coil will be...
1. The black wire from the pertronix.
2. The grey wire to your tach.

That's it.

 

[BlueNote2]

Oh, so the purple wire is what adds the resistance?!

So I keep the connection exactly the same as the purple wire was, but add a new copper wire instead of it, so it does not resist the current?

Is that right?

 

[wrestling coach]

Oh, so the purple wire is what adds the resistance?!

So I keep the connection exactly the same as the purple wire was, but add a new copper wire instead of it, so it does not resist the current?

Is that right?

Yes that is correct. YOUR new wire from the choke+ will now be the full time source of 12v to the coil when the key is in the run position. When your ignition switch is in the crank position the full 12v will come from purple/yellow wire running from your starter. When you release the key that wire drops out of play and YOUR new wire comes into play.
I have made this conversion to my 470 with the help of the posters above. It has been all good. I have set my timing at 6* BTDC. Be careful installing the magnet on your distributor shaft. Be sure it bottoms out or you could cause the rotor to sit too high in the cap and tear it up. Easy does it with a socket as you tap it home.

Dennis

 

[BlueNote2]

Thank you Dennis and Fishermark. Very helpful advice all.


Does it matter the gauge/type of wire I use? If I go to hardware store what to ask for?

 

[wrestling coach]

Yes gauge is a factor. I used 12 gauge stranded copper.

Dennis

 

[stonyloam]

The guys above have it right, just a couple of things: make sure you use a stranded (not solid) copper wire for your 12 volts and on the 470 the purple/ yellow wire comes from the slave selonoid not the starter (see diagram).

 

[Fishermark]

On the wire gauge - you cannot go too big, but you can go too small. 14 gauge would be sufficient. You want good quality wire however. I would suggest buying some tinned marine grade wire from your local boat supply place instead of the cheaper grade wire at the hardware store. Either will work, but the cheap wire is prone to corrosion.

 

[BlueNote2]

Follow-up question:
I have to connect the new Alternator Wire also, but was having trouble locating the Solenoid.

Would that wire also connect to Slave Solenoid? Same as the Purple/Yellow wire?
If so, where would I find the slave?

 

[stonyloam]

The slave is bolted to the port side of the engine block. You should have battery voltage on one of the large terminals. Looks like this https://www.mercruiserparts.com/showSpecialPicture.asp?pn=65057T1

 

[BlueNote2]

No Title

Okay, I found the slave, thank you.
The paperwork for wiring new Alternator Wire says "battery side starter solenoid", does not specify slave (does that matter).

* you can see the purple/yellow wire on right