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tubman · 02-22-2020, 10:15 AM

The "pro", of course is a hotter spark.

There are two "cons" : The first, it is not original to the car (which can make a BIG difference to many of us). The second problem with them is that when they die, they almost always die immediately, leaving you stranded, often at the most inconvenient times.

A conventional points system will usually start deteriorating slowly, giving you ample notice that you need to do some maintenance. If you are into a high performance oe a high annual mileage situation, they can be an advantage. For a "hobby car", they are not required, and the chance of an unexpected, immediate failure far outweigh any positive factors. A stock (or close to it) flathead Ford does NOT need that hot of a spark. In some cases, it may even be disadvantageous. I had an MSD "Ready to Run" distributor and 6AL box on a 276" '50 Merc in my '36 25 years ago. The spark produced by that thing was so hot that it would literally eat through the coil tower in a month or two, requiring cap replacement. There is a thread on the "H.A.M.B." right now where a guy with an MSD on a flathead is looking into installing Iridium spark plugs because the MSD is literally eating the existing plugs alive. An ignition system has to be viewed as a whole system, not just pieces and parts. When you start pushing all of that "juice" through the system, something has got to give. In the case of the guy on the "H.A.M.B.", it was the plugs; in my case it was the cap. (In case anyone is wondering, I was running marine "surface gap" plugs, designed for HEI ignitions.)

There is nothing wrong with a conventional points ignition. Unless you are running ridiculously high cylinder pressure (impossible in a flathead) you won't see any difference in performance with an HEI. The only other advantage is longevity, but with the annual mileage most of our cars get, that's just not a factor. Doing a tune up every 10 to 20 years is good for the soul and helps keep your wits sharp.

02-22-2020, 10:15 AM	#5
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 12,148	Re: pro or con HEI The "pro", of course is a hotter spark. There are two "cons" : The first, it is not original to the car (which can make a BIG difference to many of us). The second problem with them is that when they die, they almost always die immediately, leaving you stranded, often at the most inconvenient times. A conventional points system will usually start deteriorating slowly, giving you ample notice that you need to do some maintenance. If you are into a high performance oe a high annual mileage situation, they can be an advantage. For a "hobby car", they are not required, and the chance of an unexpected, immediate failure far outweigh any positive factors. A stock (or close to it) flathead Ford does NOT need that hot of a spark. In some cases, it may even be disadvantageous. I had an MSD "Ready to Run" distributor and 6AL box on a 276" '50 Merc in my '36 25 years ago. The spark produced by that thing was so hot that it would literally eat through the coil tower in a month or two, requiring cap replacement. There is a thread on the "H.A.M.B." right now where a guy with an MSD on a flathead is looking into installing Iridium spark plugs because the MSD is literally eating the existing plugs alive. An ignition system has to be viewed as a whole system, not just pieces and parts. When you start pushing all of that "juice" through the system, something has got to give. In the case of the guy on the "H.A.M.B.", it was the plugs; in my case it was the cap. (In case anyone is wondering, I was running marine "surface gap" plugs, designed for HEI ignitions.) There is nothing wrong with a conventional points ignition. Unless you are running ridiculously high cylinder pressure (impossible in a flathead) you won't see any difference in performance with an HEI. The only other advantage is longevity, but with the annual mileage most of our cars get, that's just not a factor. Doing a tune up every 10 to 20 years is good for the soul and helps keep your wits sharp.