Need more info. The year, make, model and engine info would help.
.034
Autolite AP26. Gap .050.
The correct gap is .028, according to autolite's website. Don't forget some plugs are pre-gapped and cannot be adjusted.
You will need to gap the spark plug according to manufactures recommendation or your application.
All iridium plugs never need gapping because they are 10 times harder than a platinum plug.
this depends on the spark plug you use. If you use autolite spark plugs you will need to gap them to 54 thousandths.
The Packaging. Autolite MAKES Motorcraft
The spark plug gap setting for Autolite 458 spark plugs is typically around 0.040 inches (1.01 mm). However, it's essential to check your vehicle's specifications, as some engines may require a different gap setting for optimal performance. Always adjust the gap carefully using a spark plug gap tool to ensure proper ignition.
The brand doesn't matter. You can look up tune up specifications at auto parts websites such as Advanceautoparts.com or autozone.com.
Ford sold Autolite to Honeywell when they began manufacuring the Motocraft brand.
.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.
0.025