Just bought and installed electronic conversion kit and have a Q

[brando15]

Hey guys I have a 1987 mercruiser 120 hp 153ci. I just bought the kit to convert and installed everything and it works great. I immediately noticed starting was night and day. Now I just looked at the box and I was sent the 1.5ohm coil. I understand I am suppose to use the 3ohm coil so I called the parts store back and they told me the 1.5 would be more appropriate for my application since it will be used at high rpm(racing) my question is" will I run into any issues with this? Is it actually better to use with my application? Will it overheat and will I lose any performance over the 3 ohm coil?

Thanks in advance
Brandon

 

[alldodge]

Hey guys I have a 1987 mercruiser 120 hp 153ci. I just bought the kit to convert and installed everything and it works great. I immediately noticed starting was night and day. Now I just looked at the box and I was sent the 1.5ohm coil. I understand I am suppose to use the 3ohm coil so I called the parts store back and they told me the 1.5 would be more appropriate for my application since it will be used at high rpm(racing) my question is" will I run into any issues with this? Is it actually better to use with my application? Will it overheat and will I lose any performance over the 3 ohm coil?

Thanks in advance
Brandon

:welcome: to iboats Brandon

Stated you installed a conversion kit, what kit was it? How is the manufacture

 

[Howard Sterndrive]

I'd send it back and get this:
http://www.michiganmotorz.com/delco-voyager-marine-electronic-distributor-p-120.html

 

[brando15]

It's the pertronix kit. I also tested pos and neg lead on the could for resistance and on the old one I get 2.1 ohms and the new is 2.8? Don't know if I tested it correctly.

 

[stonyloam]

if you have the Ignitor, the 1.5 will be OK, just use the stock resistance wire, and run a separate wire from the purple choke wire to the red lead on the Petronix to provide 12v to the unit. According to Petronix you need a total of about 3 ohms resistance for a 4 cyl. so the resistance wire should be about 2 ohms, so the 1.5 ohm coil will give you enough resistance.

 

[brando15]

I tried this tonight and the coil seems to get pretty hot, just as hot as the block. Is that normal? I never noticed before? Tested the coil and im getting 8.9 - 9 volts total when running. I assume that is fine too? prior it was 6 volts

 

[brando15]

I have a purple with yellow strip wire that runs from the starter to the positive side of the coil, the red wire from the pertronix dist and another red wire that I cant seem to trace. is the red wire that I cannot trace the stock resistance wire?

 

[brando15]

ok. so I have found that the purple with yellow stripe running from the starter to the positive side of the coil is the resistance wire. so the coil should be getting around 10 volts than right?

 

[achris]

No, that purple/yellow wire is the cranking bypass, and is normal wire, not resistive. The resistive wire should purple, no stripe, also running to the coil +...

 

[stonyloam]

No, that wire is not the resistance wire, that wire provides full battery voltage to the coil when the starter is turning. Your resistance wire should be a purple wire running from the choke connector the coil +. Over the years the color may have changed a little to look red.

 

[jaa241]

Brandon, I just ran in to this same similar issue with my mercruiser 140. Before anything. Is it the Ignitor I or Ignitor II? If it is the Ignitor I, return it and get Ignitor II. Then either then a Flamthrower II coil, or MSD 8222 high vib expoy coil. You need the Ignitor II which has adaptive dwell. If not you will not bit able to idle properly. I found this out after finally talking to a pertronix tech.

 

[thumpar]

When I did my 120 I used a 3.0ohm Flamethrower 2. It made the wiring much easier. I just ran a new wire in parallel to the resistance wire and taped up the ends of the resistance wire.

 

[brando15]

Thanks for the info guys. Ill have to test the wires and see whats what. Its the Ignitor I and original flamethrower coil. I currently have my old coil in right now and everything is idling and running fine but I would like to get the flamethrower coil in.

So the purple wire that goes to the choke is a resistance wire? I was told to hook up the 1.5 ohm coil to that wire?

 

[stonyloam]

Should give a total of 3. Ohms, about right.