If you call AFR or Mallory, I'm sure that they would give you some direction. I've read that many use 'as is' out of the box, or set between .035 and .038 for street use.

 

Yep, sometimes, up to 0.045".

 

I have dart 200 heads and msd distributor I gap mine at .042" don't forget a dab of never seize on your plug threads if you have alum heads :thumbsup:

 

as stated, many of the newer plugs are not meant to be gapped by the customer. Also, the design of the plug generally determines the gap. In the rare case, you may actually have to shrink the gap. One of my customers has one of the fastest door slammer 5.0 mustangs in the country, and has a very interesting cooling setup for his engine, too much to go into, but because of the way that it is designed, the turbo and a combination of other things, his spark plugs must be gapped to .008 believe it or not. Iridium plugs are not recommended to be re-gapped due to the fact that they are very brittle and can break the electrode if you try to make adjustments. On a pump gas car, like previously stated, .035-.045 is pretty much standard.

 

What coil?
Do you have a CD ignition box if so which one ?
This is going to Determine the gap.

 

HEI .045
Points .035
And as said above...some cases call for more or less...like the turbo car above...more boost=less gap or it will "blow the flame out". Even nitrous cars with large shots will do the same.

 

Thanks for the tips guys. The post above seems like a good place to start. Out of the box these plugs are set to .025" so it looks like some adjustment is in order. For what it's worth the coil is an Echlin IC-13.