Maybe I'm dim, but clicking on the little magnifying glass, presumably a search tool, doesn't work--so I don't know if this is has been asked before.

That said--I've been running a Pertronix on my stock '56 292 since 1997, with the "Flamethrower" coil. According to my notes, I gapped the plugs at .034, per the shop manual's '032-.036 range. Anyway, this seems to have been a mistake given the potency of the Flamethrower.... I'm getting ready to replace the plugs and am going to go back to the std coil (keeping the Pertronix)-- any thoughts on gapping with this this combo (Pertronix with std coil)? Info on the web is all over the map. Thanks.

Running a higher output coil like the flamethrower bypassing the standard ballast resistor and an Ignitor module does make for a fatter spark, even with standard gap.

But notice the distributor itself, cap & rotor and the materials were designed around points ignition voltages and may misfire or arc at higher RPM. Diameter increased a lot when HEI and Duraspark hit the scene. Wider plug gaps definitely raise the coil firing voltage. The question is does it do any good in your application. If there are any defects there or in the wires it will find them. Pertronix says plug gaps can be widened up to .005, not enough to matter in my book. It's worth experimenting though.

If using something as hot as a FLAMETHROWER COIL, you can widen the gap for better performance. I would gap @ the suggested gaping when FORD introduced SOLID STATE in 1974 I think the gap was .044 - I will have to confirm that). As mentioned, the STD cap and rotor may not react kindly to the increased voltage.

FORD went to a better cap/rotor in 1975 (D5AZ 12106-A/D5AZ 12300-A) to control spark crossover (this cap also replaced the FORD B7AZ 12106-A Transistorized IGN cap- BROWN - of the period). When FORD went to DS II in 1977, they used the larger cap you are used to seeing.

The only trouble is the caps came out in BLUE and later GRAY. I think you can find one in BLACK QUALITY AFTERMARKET.

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You shouldn't be going back to your 'standard' coil why ?? . you must use the matching coil for Pertronix . Gap at.038  or standard and leave it.. Ted will tell you widening doesn't do squat. 



"Came too close to dying to stop living now!"

The Ignitor 1 will work with a standard OEM ignition coil, though the primary circuit resistance must be at least 1.5 ohms. The later Ignitor modules are designed for use with low ohm coils, using their 0.7 ohm coil for example, and Ignitor 1 module will cause trouble - nominally 17 amps! Oops. I'm not sure what flavor he has. Ignitor 1 wants to see no more than 8 amps.

I messed around with gaps but now usually gap at the standard clearance, on account of the fact that as a plug is used the gap will widen a bit as the electrodes wear. When a plug is fresh it has nice square sharp edges and is easier to fire across the gap, though in practice I never leave plugs in for extended periods. If you plan on leaving them in for 40 or 50k it might not make sense to start out the gap on the high side. It took me a while to get jetting straightened out, heat range, and then as mentioned some brands just seem to work better for whatever reason.

For '64 the 292 plug gap was .030 , it seems to run fine to me. Wide plug gaps were mostly a result of the necessity of firing the very lean air fuel mixtures in the early 70s emission era engines. GM started with a .060" plug gap in their HEI and rotors were burning up. Finally, there is a school of thought that says optimum plug gap is really a function of cylinder head design, and consequently converting to electronic ignition does not change this.

If those plugs have been installed since 1997, you should post a pic or two. Be interesting to see how they've fared.

My notes on this car over the years are pretty detailed, but I've made no distinction of the Petronix being a I or II...I actually don't think there was a II in 1997 (?). It runs fine with what seems to be the car's original coil--a "yellow top." I did note that the car ran badly when I first put on the Flamethrower--timing needed adjustment. Anyway, my guess is that I had the Champion plugs installed in 2008 gapped too narrowly (.034 I noted back then) for the FT--they only have about 3200 miles on them since '08. I'll post a picture of their condition when I get around to swapping them out for new plugs later this week. 

As I understsnd it, normally a plug fires at the minimum voltage required. Maybe 6 to 9k volts or whatever. The rest (20,000 stock coil) is reserved for high load conditions, worn plugs etc. The higher voltage coils that claim "40,000 volts" allow for wider plug gaps, but they don't require wider plug gaps. It should run fine at a standard gap and a FT coil.

Don't get me wrong, it is definitely worth experimenting and see what works for you. What I noticed generally is the cross reference charts aren't particularly accurate, and some product lines have been discontinued in favor of a "one size now fits three heat ranges." Maybe.

Different manufacturers have different ways of doing things too, am running NGK right now. While it has the appearance of a considerably colder plug (short insulator nose) than what it crosses to they appear to be burning much cleaner than what they replaced. This surprised me. The jetting is pretty straight, so thought I'd run a slightly cooler plug for summertime highway use.

And as a note, a hotter ignition will allow the use of a colder plug with much less chance of fouling.

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