Spark options after HEI install?

Pi-Eyed Piper did pass the time by typing:

I don't see why apart from they usually don't fit the stock looms. Frankly I run 6mm on the ZJ but then again it's not pushing spark very far on an I6.

The HEI puts out about 33,000 volts compared to I think 17,000 volts on a stock ignition I think.. I wouldn't think stock wires would be enough.

I upgraded my 85 cj7 to an HEI and the best advice I can give you is to power the HEI directly from the battery and switch it with a relay. I mounted my relay beside the starter solenoid and used the +12v connector on the solenoid for a power source. The difference from running it off the switched power circuit is very noticeable. I don't know about the 7mm wires though. It can only result in a drop in performance so why bother. Other issues I had were with the oil dipstick placement and an overly efficient relay that would stay powered on at 7v. This meant there was enough residual from the alternator to keep it energized. Wiring it to the other switched 12v cct meant no spark when cranking over. I solved this with a diode OR to the starter solenoid. This circuit becomes freed up when you lose the old ignition. I presume you have the needed gear? The gear from my old distributor had too large a diameter hole and was unuseable. I have heard that with some distributors the old gear just has to be ground down. This wasn't true in my case. I'm tempted to try the Crane adjustable centrifugal advance kit. It's supposed to increase the power band a bit.

JJ

So are stock wires enough? Do I just regap my stock plugs, or get the plug reccomended for that year GM vehicle the HEI came out of?

The HEI I bought came out of a guys CJ, the gear is there, I asled him. and I THINK the wires are already 7mm...

are you happy with what it did for your heep?

I'm very happy with the upgrade. It idles a lot smoother, especially when damp out. I get more power at low end and this means I don't have to drop a gear when crawling along in 2nd and I need a surge of power. My gas mileage has also improved. I still had a lot of problems with my Champion plugs. As far as I am concerned Copper Champs are a POS. I crossed over to a set of Autolites and they are performing reliably.

With the HEI you should regap your plugs to at least .045" to take advantage of the fatter spark.

JJ

I used the standard plugs for the engine, but increased the gap to 0.050.

I also tried the Crane adjustable advance kit, and found that all combinations of the Crane springs provided too much advance and led to preignition, so I ended up using the stock GM HEI distributor springs. I get great performance and no preignition using the stock GM springs.