All iridium plugs never need gapping because they are 10 times harder than a platinum plug.
.034
.44
Autolite AP26. Gap .050.
You will need to gap the spark plug according to manufactures recommendation or your application.
A 2004 Chevrolet Trailblazer that has a 4.2 liter engine will have a spark plug gap of .044 inches. The best spark plugs for this vehicle are iridium spark plugs.
this depends on the spark plug you use. If you use autolite spark plugs you will need to gap them to 54 thousandths.
The standard gap for the Yamaha xs1100 is.032 for most plugs. However, the Iridium Plugs call for a gap of .044.
Bosch OE fine wire Iridium spark plug gap is preset. Do not gap.Other aftermarket spark plugs range from .040" to .044" gap.
The spark plug gap for a 1999 Mazda 626 with a 2.5L V6 engine depends on the type of spark plug. Platinum plugs have a gap of .032 inches, while iridium plugs have a gap of .044 inches. However spark plugs come pre-gapped and do not need any adjustments.
I purchased Last week autolite 3924 spark plugs and the tender said to me the book says 0.3233-03333 for this car.
.035 inch........for the ABSOLUTE best power use Autolite AT3 spark plugs. I had 65 327/365hp in 65. Motor Trend did a test on spark plugs using a 389 cu in GTO engine. They gained ten (10) HP by simple change the plugs to Autolite AT3. Good luck.
If you are running the stock HEI distributor, .045" is good.