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2.8 conversion problem


hispeedsean

New Member
Joined
Jun 11, 2013
Messages
4
Vehicle Year
1985
Transmission
Manual
well I did the conversion and now my problem is my coil is getting so hot it shuts the motor down after it runs for a couple miles do i have the wiring wrong .the wiring was kinda messed up to start thats one of the reasons for doing the conversion i thought i got it right but maybe not? any advice would be helpfull and appreciated thanks
 
Most older coil setups have 2 "+" wires.
These types of Coils heat up too fast and fail if you send then 12volts all the time.

So the setup was 12volts when starting only, then 8volts while running.

The wiring was a regular wire from the starter solenoid, it would be connect to the "+" on the coil and the Starter motor wire post on the solenoid(or the "I" post if it is a 4 post solenoid), so coil only has 12v when starter is turning over the engine, it might also have a diode.

The second wire is a "resistor wire", or there would be a ballast resistor.
It comes from the key switch(or ignition module) as 12volts, then passes through the resistor which lowers it to 7-8volts which is also connected to the coil "+".
This is the voltage to the coil when driving, so no over heated coil.


You can re-wire it yourself, you can buy ballast resistors at any auto parts stores, that's the part you really need.
The wire to the solenoid can be left off but does help on cold starts.
 
Last edited:
Use the stock coil the square TFI coil will work just fine it actually give you a spark gap around 7/8 inch so dont get bit it will hurt. If you use a ballast resistor you may have starting issues? The ignition switch dont allow for start bypass to boost coil voltage and retard the timing. In that case you add a diode from the start wire on the solenoid to the coil pos. When you turn the key on it gives ballast voltage to the coil then when you hit the starter the diode allows battery voltage to the coil for a fast start and when you let off the key it returns to ballast voltage at the coil. The ballast resistor is only necessary for points type ignitions. I have been running 4 now years with the stock TFI coil with zero issues starting or running. Autolite single platinum plugs yearly.
 
Just my opinion - I've done several DuraSpark conversions, including updating old points V-8's.
I have been told that the TFI coil will work, so you may want to leave that in place. The can type coils need the lower voltage (9V if I recall). The lower voltage keeps the coil from overheating.
If there is starting trouble when cold, you can run a wire from the starter terminal of the solenoid to the coil + side. I don't see why a diode would be needed in this case; you just need the extra voltage to get extra spark when cold and it wouldn't feed back into the lower voltage run circuit.
Don't be too concerned with a big spark because it doesn't take much to make gasoline explode and that's all you are doing. You don't need a 'high performance' ignition in even a worked over 2.8
Good coil, distributor and rotor, wires and plugs and you will be fine.
 
The last two Duraspark conversion's I did had a problem with overheating the TFI type E coil and the Duraspark module. One of the coils actually got hot enough to blister the coil, of course it quit running. I installed a 8 volt ballast resistor and no more problems.

I run a wire from the "I" side of the starter relay and have no cold start problems on either vehicle.
 
thanks i will try that but what abput the wires going to the mod the red and white do they need the 12 volts on both
 
Red on module is key on hot and white is key on start. The colors are backwards on the harness but still correct.
 
When I had my 2.8 and did this conversion, I used the tfi coil and didn't have any problems with it, wired it all up exactly as shown in the tech library.

Sent from my rooted SPH-D710 using Tapatalk 2
 

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