Well here goes, my opinions may be worth what you paid for them.
Start from stock. The stock Mopar electronic ignition system is adequate for most everything street-related. There has been some gum flapping about quality of the aftermarket stock replacement boxes. The distributors, however, are a known quantity and do their job quite efficiently. The only thing I'd suggest on a stock system is to have the distributor recurved so you can run a decent amount of initial advance and then the mechanical advance comes all in by 3000rpm. Total advance on LA motors usualy runs around 35 or 36, B/RB motors with stock heads need about 38 degrees total timing. Vacuum advance, which I use on all my vehicles. is extra.
The next step up from that is the Rev-N-Nator which looks like a factory box but has a lot of stuff going on inside. After studying their write-ups and their patent documents I have concluded that this box is for real. There is another good aftermarket plug and play box sold by
www.foursecondsflat.com. It uses a circuit designed by the guys who do Daytona Sensors and as such it should be good. The GM HEI module with four connectors, two on each end, also can make a really big spark. It needs to be attached to a heat sink with conductive grease between the module and the heat sink.
Any of the above boxes should either be used with the manufacturer's recommended coil, or else with a modern "E" core coil, like Ford used with their TFI ignition. Standard Motor Products FD-478. Look under the hood of a late '80s ford car. It's the square coil with the iron around the outside. It's more efficient and will help produce a hotter spark if the engine needs it. Everything above on this page is an inductive system which makes a single long-duration spark.
Now we move on to Capacitive Discharge Ignitions, usually called CD or CDI. There has been a real consolidation in the past few years. I liked the Accel 300+, others liked the Mallory Hyfire, there was a Holley, the Crane Cams Hi6 and of course the MSD. I have put 150,000 miles on an Accel 300+ and 80,000 miles on an analog MSD 6200 that I bought used for $40. The only problem for you is that only the MSD Digital 6 and FAST Hi6 are still available new. With these boxes I use the stock electronic distributor. All of the CD ignitions are multi-spark up to around 3000 rpm, then switch to single spark. The multi spark compensates for the CD ignition's very short spark duration.
Exceeding the usual CDI boxes is the Daytona Sensors CD-1, about twice as expensive, but seems to be really well built and has a number of useful features built in. For straight race applications the old faithful MSD 7 is very commonly used.
MSD has some more high end stuff, more pro racer-ish. Don't be fooled by the NASCAR approved boxes, they have lower maximum spark energy than their street brothers, and are forced to use analog circuitry. Of course they would work just fine on the street, but in this case just because it's sanctioned by NASCAR doesn't mean it's higher performance.
Above this are the multi-coil ignition systems run off a crank trigger, such as Electromotive. They take the crank trigger signal and calculate the timing of the spark. With these, the spark advance is calculated by speed and in some cases by load. There is 8 times as long to charge up each coil so a long duration, fat spark is produced. The spark advance curve can be programmed, no more messing with weights and springs! Just plug into your computer and go. These systems can be coil on plug or coil near plug as well as use a conventional distributor to dish out the sparks. An additional benefit of these setups is that the crank trigger is at least 10 times more accurate than the distributor. Recent articles about spark timing have pointed out how far from perfect it is. Doing away with distributors and spark plug wires is a real time- and cost- saver.
That's my rundown on systems. It is important to note that just because a system is CAPABLE of producing a 50KV spark, the actual spark voltage is the amount that is required to jump the gap of the spark plug. Usually this is in the neighborhood of 28KV.
One book that goes into some detail was written by Dr. Christopher Jacobs, who wrote The Doctor's Guide to High Performance Ignition and I guess is still making ignition systems. I thought the company was gone. He writes about things in very attractive engineeringese and I don't know what to believe and what not to believe. I believe most everything he sells is CDI. I have a feeling he gives imaginative names to everyday physical processes and makes it sound like he's splitting the atom. One of my systems is using a Jacobs chrome coil that I bought 30 years ago, so it seems his equipment has quality.
Unless your ignition system is really down and out you won't see a noticeable increase in power or efficiency by going to a more capable system. I know that and I do it anyway. But take a good conventional system and install a high $$$ CDI and there will be only a slight improvement, if any. The "placebo effect" assures that you will probably notice an improvement, but this is because you expect it to happen, even if it does not.
R.
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