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Hey guys. I run a msd 6a with a hp coil, above 9:3 compression, larger valves, header, 4v intake, etc.
After a short while I noticed a loss of power and found my plugs badly worn. The center electrode was no long flat, but rather pointed. I am running the stock plugs for a 78 300. What plug should I be using?
Per Harte3's advice, I've been running the EFI spark plugs. The electrode is slightly longer (maybe 1/16" - 1/8"), which places it slightly further into the combustion chamber. Whether or not it truly makes a difference, I don't think one could really tell by the seat of the pants, but they seem to run really nicely.
Autolite Coppers of NGKs should do the trick. If you are running extra gap like 50 or more this might cause the plugs to wear a little faster.
Thanks, H. I run .055 gap. From what I have read, I was lucky to get 40--50k miles from my plugs. Truth be told, I should have changed them long ago, but I got a bit burned out on the automotive work.
I remember you recommending an efi plug years ago.
My ole girl "Beulah" as i call her, prefers MC sp435 @ .055 gap. Have tried iridium, platinum, double plat, you name it. I too have a big valve ported head, higher static compression, upgraded ignition, clifford C intake w/ 4 bbl, and more. She likes the motorcraft coppers. They get swapped out every other year. Next of the list is sidegapping, and a few other "tricks" to see if it makes a difference. Cant seem to find indexing washers for the efi plugs, 18mm i think, nor do i know if it would merit the cost/effort to begin with. Would be interesting to run some tests and find out though.
I ran Autolite APP 5125 double platinum and 0.050" gap and got about 25-30k out of the. When I pulled them I found several platinum electrodes missing! if the electrodes stay put I'd run them again.
I'm not using a distributor but a Wasted Spark coil pack from a minivan and can choose a dwell (of 3ms). I ran the spark gap of the minivan instead of stock *shrugs*
Although I may fall for your coil pack system and have to have one, thereby burning more money, I am fascinated. Can you pls. show some pix and describe/tell about the system?
I have a VEMS EFI (Megasquirt fork a long time ago and now it's own thing), but I'm sure most aftermarket or DIY EFI's can do what I did.
Coil Pack and Distributor
Distributors only used for Oil Pump and Triggering. This is a '96 non-tfi basic Hall sensor distributor which has a weird tooth thing (one windows is wider) that I couldn't make work and eventually JB weld epoxied a magnet and Hall-Sensor on the Cap and Rotor. So Rising Edge was nice and uniform, but falling edge had one that differs so is used for Primary Triggering while the cap'n'rotor hall sensor is for phasing. Eventually I'd like to add a 36-1 crank trigger wheel.
Once in, simply tune the various tables! Alternatively One might be able to stuff an EDIS like system in and do without the EFI part and use a Carb instead.
TL;DR: Used '96 distributor for nice digital signal to a DIY EFI and a pile of junkyard parts
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