dmaclaren

I have read both and in pulling all my plugs, they are in the .042 - 6 range.

Are my gaps off from the previous owner or is that right? it's a 1969 351w

BuckeyeDemon

the shop set mine at .030" lots of people run .035".

the bigger the gap, the higher the voltage, which i would expect to be harder on wires/caps/rotors.

dmaclaren

I'm running electronic ignition, I have them gaped at .046, wonder if I should reduce to the .036. I was just reading that for elec. ign., .04x is the way to go.

Now I am not sure

BuckeyeDemon

there seems to be a love affair with increasing the gap with a more powerful ignition system. i personally don't understand the rationale. maybe someone here will explain it to me.

The_Dude

I run .045 with an electronic ignition and .036 with points. The bigger gap allows for a bigger fatter spark. An electronic ignition has more volts to jump the larger gap.

musnicki

I have mine at 40, NGK plugs with MSD 6AL box. I don't notice a difference, I was told between 35 and 45, so I set it at 40. A bigger spark makes for a more complete burn I guess?

Starfury

It helps ignite the mix more reliably. GM HEI systems (which use ~100kV coils) are commonly run with a .050-.060" gap.

With a stock coil and electronic ignition, I'd say .035". With an aftermarket 40kV coil, call it .040.-.045".