Hi everyone,

I recently purchased an MSD ready to run billet distributor and am getting ready to wire it. Upon reading the instructions I realized I cannot use the original ignition resistance wire as the coil + side must be wired to a 12 volt switched source. Could someone please tell me where they found the easiest 12 volt switched source to be? I don't have a problem tapping into an existing wire if that will work, however I am unsure of the closest/best location to tap into. I also need the 12 volt switched source for an electric choke on a Holley Carb. Can I use the same one I will use for the coil for this also?

Thanks in advance for your time,

Camaro350

One thing I forgot to mention, will it be necessary to remove the original resistance wire completely or can I just cut and tape off the end?

Thanks again.

[This message has been edited by camaro350 (edited 04-13-2001).]

What I'll do is, use one of the switched 12v outputs from the fuse box, inside the car, (with a test light check the male spade connectors)and run it to the engine compartment to activate one or two 30 amp relays. That way you make sure you have full battery voltage to the ignition and choke. It's not too difficult and remember to use fuses to protect against short circuits. As for the resistance wire you can hold it secure and hidden without having to cut it, you never know what future brings...

I removed my resistance wire from the harness and cut the original terminal off. Then I soldered a new piece of wire to the terminal and re-inserted it into the harness.
I'm pretty sure you have to remove the whole wire. Its pretty easy! if you don't want to remove the original wire, I would do the method ORENCH suggested.

Thanks for the responses. They both sound like excellent solutions, however I was hoping for something a little simpler to do. However if there is not any easier way, I will probably go with ORENCH's relay method as I will still have the resistance wire in place in case I ever decide to go back to a points ignition.

Thanks again everyone, and keep the suggestions coming, as I plan to wire in the dist. tomorrow and hopefully fire up the newly rebuilt engine I just finished.

Camaro350

Hello everyone,

Here's what I did, I haven't applied power yet, and want to ask your opinion as to whether it should work ok and be safe:

I purchased a 30 amp relay as per ORENCH's suggestion, and ran a fused power wire from the "BACKUP" light fuse on the fuse box (I tested this with a voltmeter and found that it was switched, I had 12 volts present both when the key was in the "run" position and in the "crank" position, however it dropped off to about 0.1 when the key was switched off). I connected this wire to the "wire from switch" terminal on the relay (I'm assuming that is the power wire that picks up the relay, so instead of using the toggle switch, my ignition switch should work in the same manner? ). I then took a new lead (14 awg) from the battery + side to the "power source" or "B" terminal on the relay. I ran one lead from the "to lights/accys" terminal to the + side of the coil and I tapped into this lead for the elec. choke power. The 4th terminal of the relay is grounded. I was thinking on just placing the wire coming from the fuse hookup behind the fuse and then reinserting the fuse, however, does anyone know of a more permanent secure way to affix this wire? I don't want it to vibrate loose and the engine to die when I'm driving on the highway or something. I used approx 14-16 awg wire for all the leads, is this heavy enough to carry the current w/o overheating? It was what came in the relay wiring kit, however the relay was intended for accy's or foglamps. If not, what guage should I use? Is the relay the correct type?

Theoretically it seems it should work. Does anyone know if it will be ok? I sure as heck don't want to start a fire, is my power wire heavy enough? Is the relay trigger wire heavy enough? Will the relay remain picked up when the starter is cranking? I believe there is about 10-11.1 volts present at that BACKUP wire when the starter is cranking. Please let me know if this is ok, or if I need to change anything ASAP as I plan on firing this engine up tomorrow for the first time and don't want to fry anything.

Thank-you again for everything, sorry about the numerous ?'s in this post, lol, but I want to be sure everything is ok before attempting to fire up the engine.

Regards,

Camaro350

first off, sounds like your relay is hooked up correctly, but I would check the voltage on the "backup lights" terminal when the backup lights are on. I believe the relay should work with anything from 9 to 20 volts sucessfully and without problems. The wire size sounds OK. the relay should hadden this no prob. a few words of caution. first, any wires that pass through the firewall, should have a gromet on them to prevent shorting. second, fuse the wire going to the battery in case something does short out WITHIN ONE FOOT OF THE BATTERY!!!! that way if it shorts, the fuse blows and the wire is dead, without the fuse, if it shorts, the wire could still be live and burn!
I left this for last. If you wanted to rewire it, you could successfully run the relay from the original distributer wire(resistance wire). I believe they put out around 10-11 volts. then you wouldn't have to run anything through the firewall. run the resistance wire to the "from Switch" input on the relay, run a ground wire to the body(firewall) and then connect the battery and distributer as before. this way, it is run from the original wire and your sure it will be on when you need it, and the relay and all wiring will be under the hood.
Do not just stick the wire behind the fuse, you will be askin for trouble. Either splice it into a wire or they do sell(atleast they used to) fuse taps. you may have to hunt for them, but they go into your fuse box, then the fuse snaps into the tap, and there is a terminal coming off of the tap that you can hook a wire to. Hope this answers all your questions, and don't forget to fuse the lead from the battery no matter where you put the relay. I've seen a few cars burn because someone wanted an amp in the trunk, or foglights and thought they didn't have to fuse it. WRONG, and now they need new cars. I can't stress this enough!!!-JOE-

Joe is correct, you might want to test if the same ignition wire switches on the relay. It's easier that way. Remember the protection fuses, an inexpensive assurance.

I just want to say thank-you to all that helped, especially Radio Joe and ORENCH. The wiring was perfect! She fired on about the 3rd turn of the starter, after cranking a few times with the coil wire off to prime the carb. The choke also operates perfectly. Thanks again for informing me that I could use a relay. I never even thought of that, I knew how relays operated and how to wire them, however it never occured to me that it was possible to hook one up to work in this situation. I also did not know where to get the switched 12 volts from, however when I went back and tested all of the spades again, the one right next to the backup light fuse behaved in the same manner as the backup fuse, so I fabricated a lead wire with a female spade terminal and wire-nutted it to the lead I had coming from the relay coil. I also fused the power to the relay coil and I cut an inline fuse into the main power feed from the batt that is feeding the ign and choke. Nothing got hot and no fuses blew, so I'm assuming everything is safe and the wire is heavy enough.

Thanks again for helping me out on this, I really appreciate it.

Regards,

Camaro350

Glad to help, now go take it for a spin!!!!-JOE-