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autolite plugs


Well-Known Member
Local time
1:52 PM
Feb 18, 2021
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central ny
what is the difference between autolite 4275 and 75 plugs
From years with a Harley-Davidson motorcycles running Autolite 65 and 4265 the difference was the 65 had a black shell and the 4265 had a nickel plated shell. Black shell if sat outside long enough would rust.
Do not know if it is Nickel but it is some sort of plating. A little known fact: Chrys engineers developed Nickel plating & it was used during the development of the A bomb.
Must have been a particular type of nickel plating as nickel plating has been used as an available finish for handguns since the latter half of the 1800s.
went from xr5 ngk to 4275 autolites. the porcelain is shorter on the 4275 so must be a cooler plug. dida check on the 4275 they seem to run cleaner. 4275 are a non resister plug so maybe getting a hotter spark.