Thanks to recommendations from site supporters, I received a new HEI-ready engine wiring harness yesterday to complete a conversion from old factory points-type distributor to HEI. Though still wrapped, I can see the modified wire and connector that snaps into the "battery" spade connector in the new HEI distributor cap. Yeah, no cutting or splicing wires!

BUT...there is also a three-pronged connector with red, black and brown wire coming from the base of the new HEI dizzy that I don't know what to do with. The Haynes manual is no help, since it assumes the owner already has HEI installed and only says "disconnect existing wiring...".

What is this for and what I am supposed to do with it (please don't say "clip it off" like the kid at the parts store said)? I was hoping to just plug in the harness and go, but I'm no longer sure of this.

Thanks, everyone.

there's lot's of info on this in the FAQ,,here's one link u can sort thru,,lotta info..:)



http://67-72chevytrucks.com/vboard/showthread.php?t=208440&highlight=HEI+swap

http://67-72chevytrucks.com/vboard/showthread.php?t=195964&highlight=HEI+swap

on the oposite side of the cap, where the tach and 12 volt wires go, there is a place for that mystery plug.

longhorn man,,that was a sure DUH on my part,what i get for not paying attention to what i was reading or seeing..:o

lol... we all make that kind of mistake.... I totally bugared up a VIN last night trying to decode it from memory instead of the cheat sheet I keep right here in my desk.

I just ran 1 wire from my fuse box to the HEI for my upgrade....what does your "wiring harnass" consist of? All you need to do is run 12 volts to it instead of the 6 volts that ran to the points coil...

and like longhornman said, the mystery plugs goes into your coil in front of the dizzy...don't throw the instructions away yet! If it won't reachh then you need to rotate all of the wires one way or the other to get the square box on the top closer to it...

Man, pictures are great. Here's what I was missing (thanks to all who posted, and so quickly, too):

The black 3-wired plug in question inserts into the distributor cap tab, behind the "battery" and "tach" tabs. I didn't realize that there was room for both the black plug and the single battery wire in the cap tab.

I can't wait to get this together this week and fire it up. I'll post results afterward.

Thanks, y'all.