camaroeater

Plugs are Motorcraft ASF42C, I have heard many different gaps for these. When I pulled the old ones I checked one and it was.045" or lower and these were installed at Ford.

67mustang302

If it's stock ignition then gap it to stock, which I think is .050

WhiteWindsor

I believe stock gap is actually .054 but anywherethere abouts will be fine.

FivePointOhh

what would happen if you have stock ignition and you gapped it to lets say.....45 or even .40....hell even .35 what would it do?

ColdCityMustang

I don't know what happens with a small gap? Small spark maybe with less of a burn? I;m gapped to .030 for top end boost reasons, my ignition is stock and I haven't seen any adverse effects. Anyone else shed some light?

camaroeater

The old ASF42C plugs that FORD installed are gaped at(.040"-.045") which is the same gap that the new ASF42C plug are out of the box. Haynes manual says .050 and autozone looked it up and said it .054. Im ****en lost.

haromaster87

If it's any help, I gapped my 86's plugs to .050 and it runs like a charm. I would go .050

Gronk72

As did I to my 88 with the same outcome.

BlackMagik

If you gap it too small it will produce ashort spark which will kill performance. If you gap it too wide it will arch and again cause a poor spark. Id suggest going with as close to stock or w/e your system requires as possible to get max performance out of the plugs. Haynes is a good place to look. If you have some time to wait i can look it up on the service software at work tomorrowand give you an exact answer for your year and model.

camaroeater

I think I'll just flip a coin I guess....tails=.045" and heads=.054". I hate doing **** when I not 100% sure about something.

Black Magic, I appreciate you looking up the gap for me. The only thing is that my parts should arrive today.