well i am trying to help out my aunt...she bought a 77 f150 with a 400 in it. it has elec. distributor. motor went bad, they bought a 390 with points dist. in it. how can i wire the 390 without having to buy a new distributor?????????? I have read thru some of the other threads to try to figure it out on my own but i guess i aint smart enuf. any help i can get to fix the problem would be much appriciated.

 

Find the coil wire for the electronic system. It should be red/green I believe. Get a older round style coil with the threaded posts, and hook this wire to the + terminal of the older style coil. Hook the wire from the points dist to the negative terminal of the old style coil. It should run.

 

Franklin2 thanks for the reply. i am assuming that the wire i need is the one that went to the slide on cap for the t-post style coil. if that is the one....i have tried that and cannot get it to fire at all. i am not real good when it comes to wiring but i try to do my best. anyway, the wire i hooked up comes hot when i turn the key on. the wire is in the loom that runs out on to the motor. the motor rolls but does not attempt to fire.any other suggestions to try?

 

Does the trigger wire pulse to ground as the motor turns over? There should be one wire that is constant hot with the switch on, it goes to the + on the coil. Then there is a wire that grounds intermittently to trip the coil.

I believe most all of this should by pass the duraspark module.

 

Not sure what you want but here is a basic diagram of how it works.



The points are just an off and on switch to turn the power on and off through the coil to ground return. When the points open the coil fires.

Here is another diagram.


You can put a test light from ground to the wire that runs from the coil to the points and it should flash as the engine is cranked. If it does not flash the points are not closing or you have no power going to the coil on the other wire to the coil.
The other wire on the coil should have power at all times the key is on.

For more information read this link below:
Street2Mud - Welcome! > Electrical System & Ignition
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well i decided to check the gap on the point and re set them to 21 put the batterycharger on it and left it for a couple hours..... came back hit the key and the old girl has life. thanks to all your helpful hints i think it was the points causing the problem. many thanks guys