Whether I get the NGK Iridiums or the Autolites sparkplugs, which gap should I use? The 0.035 seems to be with what i am reading on here. But the 0.040 is the the gap in the manual for the V8. I am wanting to get my plugs asap.

 

Use sparkplugs.com as a reference for ALL the recommended gaps for all spark plugs available for your truck.

NGK Iridiums, for the V8HO, sparkplugs.com states .044"

Autolite Iridiums call for .040"

Honestly, there has been alot of debate on all of this, and the difference between .040" and .044" is really not worth your concern.

Using this theory:

http://www.se-r.net/engine/platinum_copper_ngk.html

After reading this theory, it makes Sense for NGK to have made there gap .044" instead of the reference OEM .040". But as you can see, autolite simply sticks with the .040".

Just use sparkplugs.com as a reference and you can't loose. Best site for plugs IMO.

 

I did .044 no problems. I've heard some say that they come pre-gapped at .044 Mine did not. They came .035 And I made sure they were for my J motor. Careful if you have to set the gap, as the electrode is super thin.