Pertronix spark plug gap

[Zoofly]

I'm going to change out my spark plugs. This will be the first time I've changed them since I installed a Pertronix electronic ignition in my distributor about 3 years ago. My spider is a 78 and the spark plug gap is 0.6-0.7mm (non-resistor) and 0.7-0.88mm (resister) according to my Clymer manual. First question is what's the difference between non-resistor and resistor? Second question is, should the spark plug gap be different now that I'm running an electronic distributor instead of points? Any insight would be helpful. Thanks

[RRoller123]

The resistor plugs have an inline resistor to help suppress radio noise production.

[18Fiatsandcounting]

Non-resistor spark plugs are not used much anymore, both for the radio noise issues as mentioned above by RRoller, but also because the radio frequency interference (RFI) on non-resistor plugs can also affect the sensitive electronics of modern cars. However, you can still buy non-resistor plugs; for example, the Champion spark plug website suggests either a N9YC (non-resistor) or an RN9YC (the resistor version) for the spiders. In these older cars, you could use either, but I would use the resistor version. The guy at the stoplight next to you in the 2020 model car might appreciate it, even if it doesn't make a huge difference in your Fiat. Note that FM is less sensitive to RFI than the AM bands. Same reason as with lightning storms.

As for the plug gap, I think that is mostly a function of your coil. If your electronic ignition still uses the original coil, I would go with the original specs for spiders, which is somewhere in the vicinity of 0.023" to 0.027". Fully electronic ignitions including a new coil might be larger, and if that's the case, I would consult the manufacturer of the electronic ignition. I usually just set mine to 0.025" (about 0.64 mm) and forget about it. But, then again, I'm old school with points and condensers.

-Bryan

[baltobernie]

+1
Running Pertronix and blue Bosch coil for 10 years with standard plug gap. The module only affects the timing of the spark, not the strength.

[Zoofly]

I'm running the Flamethrower coil, so I'll go with the recommended gap for OEM. Thanks for the replies.

[MattVAS]

JOKE POST!!!!
87753OOOOOOOOONINNNNNNNE

[18Fiatsandcounting]

Jenny, Jenny, who can I turn to???

[aj81spider]

You'll never get her that way. You're calling the wrong number.

It's 867-5309

[18Fiatsandcounting]

Yeah, I noticed that! Probably need the area code, too!

Tommy Tutone, aka Bryan
For those that haven't gotten the joke: https://www.youtube.com/watch?v=6WTdTwcmxyo