HEI Ignition Wiring

Okay, I finally broke down and purchased a DUI ignition/distributor. What is the best way to wire this with minimal effort/disruption of original wiring harness? In other words, what should I tap into to get the 12v keyed hot wire and how do I identify the tachometer wire under the hood? I was hoping to power the dist. by just jumpering off of the existing positive wire on the original coil, but I was told that this didn't provide full 12 volts.

Thanks in advance.

 

take a look at the diagram and see where the resistance wire starts and tap in there. Mine happend to start at the main engine wiring harness connector.

 

It will work off the existing wire if you tap in before the resistor (as mentioned above)..But, something to keep in mind...they work their very best with a heavy gauge wire. In other words, try to make it as clean as possible with as few things that can cut the power to it as possible. I actually hooked my to a heavy switch (this is not for everyone) but try to keep the wire heavy from the battery, through the switch, all the way to the ign. I will not use smaller that 10 gauge...Trust me when I tell you there IS a difference.
Tach wire...It most likely would have been hooked to the negative side of your old coil.

 

Excellent write up on this upgrade. You will be extremely happy with results. Mucho
voltage and none of the headaches of the factory electronic ignition.

http://www.geocities.com/jeeperaz/hei.htm