Ballast Resistor
Yes, well, when I was directly involved with the initial development of the GM HEI, we did not design the system to be a performance system, it was to build a 50K mile, low to no maintenance, consistently higher output ignition system to fire extended spark plug gaps over points system output levels.
YES, I worked directly for Zora Arkus-Duntov in Skunk Works, and was sent to help the High Energy Ignition program design and development.
The reason for the wider gaps, as EMISSIONS settings for more and more strict, l4ess fuel molecules were present in the mixture, and they stayed farther apart, so, lighting them off became more critical as to spark plug gaps. The HEI was not, is not, and never will be a performance ignition system, but does work well on GM crate engines, including their performance series ZZ units.
One fallacy about HEi and other ignition systems, such as MSD CD systems is that morons within the ignition system world insist spark plug gaps be jacked to the moon, that this helps. IT DOES NOT, maximum spark plug gap with both HEI, and MSD CD is set at .045, NO LARGER. During further development of the then new HEI, we began to see module failures caused by slow coil failure changing module load. MANY new cars left Pontiac, Olds and Buick deale5rs, only to have module failures a week later. We determined that the engineers at those 3 divisions were leaning out the mixtures for emissions even further, and opening up the spark plug gaps even further, to first, .060, then, worse, to .080. The added gap caused the epoxy filled coils in cap to overheat, as epoxy does not bleed off heat, to the point the modules were overworked seriously, to failure. The warranty fix was simple, replace the module and coil, reset the spark plug gaps back down to the engineering spec of .045 maximum, fixed the issues.
Today, we see and hear of numerous module failures on coil in cap HEI caused by coils slowly failing, with the explanation "That HEI module just failed, FOR NO APPARENT REASON". Well, NOTHING fails "for no apparent reason", there is a reason for failure for everything, including HEI module failures. There are kits for GM to move the coil off the large HEI cap, use a round, oil filled coil, that stops the module problems with the HEI for GM people.
Look at my avatar, no coil in cap, it is round, oil filled, and remote mounted from the distributor. That is the way it should be. We designed the HEI to be one unit, no off body parts, which made for NO oil filled coils, that was a serious mistake. Good that MOPAR cannot have the coil in the cap, that is a solid benefit.
Over work any ignition module, and it will fail, including MSD ignition boxes caused by 70 percent Blaster coil failure when those coil's production was moved, in 2003, from Andover, Indiana, to just across the Rio Grande, to Pro-Bobbin, in Juarez, Mexico.
So, the HEI is not a performance ignition, but, not so great engineers have over hype advertised them as the end all ignition system that they are not. So, if you go with any sort of HEI for a MOPAR setup, good, just use a round, oil filled coil, good plug wires, and no larger than .045 spark plug gap, NO MATTER WHAT THE SALES BS SAYS.
As far as one coil per spark plug sysems, complicated, great, but not practical for everybody.