Changing to electronic distributor, need wiring diagram

[Oregonbythesea]

I have a 302 Ford on an older Mercruiser that had an electronic distributor installed. The problem I have is that it won't run. I got a new coil and according to what I have read, a ballast resistor is not needed. The distributor has two wires coming out of the onboard module within the distributor. My question is; what is a very simple wiring so I can see if I can get the engine running before trying to figure out what else might be wrong. I have 12 volts on one wire from the key and can eliminate the resistor wire and just feed 12 volts on it to the plus on the coil. Now, what should I do from the distributor and negative on the coil? Thanks to anyone that can help on this.

 

[Don S]

Re: Changing to electronic distributor, need wiring diagram

Without knowing exactly what type distributor you have, it's impossible to tell you how to wire it. Pictures may help.

 

[thumpar]

Re: Changing to electronic distributor, need wiring diagram

If it is a Pertronix unit that was put in you can look here http://www.pertronix.com/support/manuals/pdf/ignitor12vneg.pdf

If not let use know what you have.

 

[Aloysius]

Re: Changing to electronic distributor, need wiring diagram

The simplest and cleanest installation is to eliminate the ballast resistor and use an internally resisted coil. ALL "hot" wires go to the "+" terminal of the coil, including the hot wire to the Pertronix; the ground (-) goes from the (-) side of the coil to the Pertronix.

I've got 2 setups like this..302 Fords..pleasurecraft. Prestolite distributors. The Pertronix MUST see a full 12 volts to work.

 

[Oregonbythesea]

Re: Changing to electronic distributor, need wiring diagram

Aloysius, I thank you for the information on how your two engines run with the setup. My only question is about the ballast resistor, I keep reading that it is better not to have any resistor in the system. Did you keep yours in line in the running position at the key or an internal resistor on the coil?

 

[Aloysius]

Re: Changing to electronic distributor, need wiring diagram

I switched to internally resisted coils, and bypassed the ballast resistor completely. no problems.

The reduced voltage (resistor) is to keep the points/coil from overheating. It's not the actual 12 volts that creates the spark..it's the collapse of the electromagnetic field in the coil that induces the spark. solid state pickups need the full 12 volts all the time. Frankly, I'm not positive that you can't run the existing coil, but I doubt it.

 

[Don S]

Re: Changing to electronic distributor, need wiring diagram

I switched to internally resisted coils, and bypassed the ballast resistor completely. no problems.

but an internally resisted coil is the same thing as having a ballast resistor or resistor wire.

 

[Aloysius]

Re: Changing to electronic distributor, need wiring diagram

Well,sure, you could still run the coil through the ballast, and feed the Pertronix from the "hot" side of the ballast, but it is cleaner and neater without the ballast/resistor. Besides, the external resistor is just something else to fail.

 

[GLENN M]

Re: Changing to electronic distributor, need wiring diagram

ballast resister is to protect points no points no ballast resistor

 

[GLENN M]

Re: Changing to electronic distributor, need wiring diagram

did i say that, no you must run point coil. with petroinics and 3ohm resister with 4cyl,and 1.5 ohm with 6or8 cyl

 

[Oregonbythesea]

Re: Changing to electronic distributor, need wiring diagram

Ok, I am going to add a little to this post for anyone else that happens to get into this mess. I replaced the coil with a non resistor type and let the ballast resistor in the system as it was. I couldn't get it started and after about a day of checking almost everything, checked the batteries. I had been cranking on this engine for a full day without it ever giving me a problem turning over. When I put the fancy new charger on it registered a 50% charge in the set. I let it charge for about 4 hours and it started on the first turn. These electronic distributors will not start the engine if it doesn't have a solid 12 while cranking. Before I put the charger on, I check the voltage while cranking and it dropped to 7.5 volts. A point system probably would have started but not an electronic. I hope no one else has to go through a whole day of work for lack of checking battery charge.

 

[thumpar]

Re: Changing to electronic distributor, need wiring diagram

When I switched to Pertronix ignition I also switched to the Flamethrower coil they sell. Bypassed the resistor wire and all is well.

 

[Don S]

Re: Changing to electronic distributor, need wiring diagram

Ok, I am going to add a little to this post for anyone else that happens to get into this mess. I replaced the coil with a non resistor type and let the ballast resistor in the system as it was. I couldn't get it started and after about a day of checking almost everything, checked the batteries. I had been cranking on this engine for a full day without it ever giving me a problem turning over. When I put the fancy new charger on it registered a 50% charge in the set. I let it charge for about 4 hours and it started on the first turn. These electronic distributors will not start the engine if it doesn't have a solid 12 while cranking. Before I put the charger on, I check the voltage while cranking and it dropped to 7.5 volts. A point system probably would have started but not an electronic. I hope no one else has to go through a whole day of work for lack of checking battery charge.

That is the problem with trying to troubleshoot while setting at a computer and not by the engine.
I know that an engine with electronic ignition will not start if the voltage is too low, but there was no mention that the engine was turning over slow (and it was with that much voltage drop)
When you can't hear, see, feel or smell what is going on you are missing most of the troublshooting process experienced techs use.

 

[Aloysius]

Re: Changing to electronic distributor, need wiring diagram

There's a REASON that they had a bypass of the resistor wire/ballast WHEN CRANKING. Voltage Drop! Some Pertronix will work PART of the time with the resistor in the circuit..the cutoff is about 10 volts. ALL! cars/boats/whatever have some voltage drop when cranking..the starter takes alot of current to run.

I had a bad connection at the key switch..I'd crank, and as soon as I quit cranking it would light off. Other engine started perfectly. Voltage would drop below 10 volts when cranking, but returned to normal when the starter stopped. Momentum let the engine turn over enough to light one or 2 cylinders.

A defective starter (internal short) will also cause a huge voltage drop because of the tremendous current draw.

 

[erock194]

Re: Changing to electronic distributor, need wiring diagram

I put the Ignitor in my 260 Merc. Hooked 12 volts to Ignitor and ran the coil through resistor wire. After running for about 15 mins the engine would sputter and wouldn't go above 1800 rpm. Ran 12 volts to coil and presto! Ran perfect. I was told running a constant 12 volts will cook distributor. So I purchased the recommended FlameThrower 1.5 ohm 40,000 volt coil. I am installing it this week and will let you know how it goes. I have done a lot of head scratching on this one. I think when you put the conversion in that they should tell you it doesn't function properly unless your upgrade coils. Well at least I hope it does. Spent more time in the slip then on the water.

 

[Aloysius]

Re: Changing to electronic distributor, need wiring diagram

"DWELL" is the period of time the points were closed, allowing an electromagnetic charge/field to build up in the coil. Breaking this field momentarily allows the field to collapse, and induces spark. Solid state units have much longer dwell times, thus more current flows through them. This builds a stronger field, but creates more heat in the process.

We're back to where I started..12 volts to the igniter, internally resisted coil. Been there, done that..twice.