ignition system ?????

slantsixdan said
Sure, butso what? The stock (Mopar) style coil is not the correct one to use with HEI. Whatever ignition system you pick, its components have to be matched to one another.

No need to guess or assume here; go read the HEI article I linked; there are oscilloscope traces comparing Mopar electronic to HEI on the same engine. Note the higher voltage and longer spark duration with HEI.

But that is the problem. Most all of the proponents of the HEI module just swap the mopar module for a GM module and call it done. Plus they believe that the ballast resistor can be removed. It can be if all the parts are matched as you say but if they aren't the ballast is still required.

The fact that the HEI system o-scope trace shows a higher voltage tells me that the comparison is not apples to apples, something else is different between the two tests. In an inductive ignition the voltage in the coil will rise to the point that a spark occurs, if everything else was the same there would be no difference in the voltage between the two systems. Likely they gapped the plugs wider for the HEI system.

As much as the marketeers for the 45000 volt coil would like you to believe that their's is so much better than company B's 35000 volt coil the fact of the matter is a spark occurs down in the high 1x000 volt range so those coils will never generate the voltage they are advertised to.

The down side of all inductive ignition systems is as the rpm increases the time available to saturate the coil goes down resulting in less potential to create a spark. The balancing game the ignition design engineers have to play is ensuring that the system can produce a reliable spark at high rpms while not over driving the coil at low rpms resulting premature failure. The measure of goodness of an inductive ignition system is how high in the rpm range it can continue to supply a reliable spark. Down at idle and low mid range rpm they all work acceptably.

The GM HEI was very very good system, probably the best at the time. The mopar system was also very good. Using a stock GM module without the proper coil to go with it is not as good as the stock mopar system. There are module available from the aftermarket for both mopar and GM that have the abilility to vary the dwell and when matched with the proper coil will extend the rpm range way beyond the stock systems.