spark plug gap

Z-man

Member
I have purchased autolite 386 spark plugs and the box tells me to gap before install does anyone know the gap setting? looking at the box to does not tell me the gap normally I just put plugs in and don't gap them but I think most plugs come pre-gapped
 
To bad you didn't check the archives you would have seen most are using the Autolite 3116 spark plugs as they seem to work better.
 
I set the gap to .025 You should always check the gap on new plugs. I have found some set way to big out of the box. I think the 386 plug is a resistor plug and will work, but as Richard said, the 3116 plugs do seem to work better. When I got my TO20 I installed the 386 plugs because they came with a tune up kit I bought online at the time and I ran them for a few years. I later switched to the 3116s and the engine seemed to respond much better.

Dan
 
If your running the original 6V ign, run the gap at .025
If you stepped up to a 12V system you could run them out to .045
GM tried running the gap out to .060 in the 80's on a normal ignition system and ran into problems with misfires and premamture ign componenets failure. They later came out and dropped the max gap to .045 in all distributor ignition vehicles. The Distributorless ignition cars are still running up to the .060 plug gap.
Generally the wider gap will get you a tad bit hotter spark and a better burn. Hotter spark should increase your power, reduce fouling and get a smoother running engine.
 
If you are working the tractor hard often then you will be fine with either Autolite 3116 or Champion D18Y. If you are just doing light work and not working it hard then you might experience plug fouling. If you are working it lightly then you would want to get a Champion D21 which is a hotter plug. Autolite does not offer a hotter non resistor plug than the 3116. I have ran both Autolites and Champions and have not had any troubles with either brand. Some people say Champions are junk, or Autolites are junk but I find either plug works fine if you have quality points, copper cored spark plug wires,and a distributor cap and rotor with brass contacts and a good coil. Too many times the spark plugs get blamed when it's actually poor quality parts installed on the rest of the ignition system.
 

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