Plug gap for best efficiency

[Black1987Stang]

I just picked up some Autolite 25's for my stang, has cast iron Windsor Jr. heads on it, the one I just took out of the box is at .043 gap using my feeler gauges, what should i change it too, I know stock is .054, I also have an MSD box, should I go up at all?, Ive been searching alot on here and read alot of people actually going lower to like .040-.045 gap for better performance, or at least better start-ups, idling n such (low-rpm driving). I wont be beating on it, just cruising, would a lower gap be more efficient or a bigger gap?....Im changing the plugs for a 14 hour drive ill be doing soon just for extra insurance so what gap would all of you recommend? Thanks

 

[TomCat]

I'd just stick with the .054

 

[Shakerhood]

I'd just stick with the .054

X2, I would stick with Ford's Specs.

 

[fastranger347]

yea i know i will be ostisized for this but; i have a crane hi-6,crane coil,motorsport 9mm wires and use autolite plugs @ .075 gap, the ignition has enough energy in it so why not use it??? it idles great and pulls to my 6,500 reline without missing, when i go to apower adder i will gap them at .050 and go from there

 

[DMAN302]

Ford spec is very popular...I have used it and as of late I've used .045 with my last set and found no difference. Only thing I have noticed is that while now running a set of AR3924's ( come from autolite with a 2mm cut back strap) that the plugs are cleaner...I can't say why though, might be a little better burn, but as stated I can't say for sure at this time.