Changing Spark Plug Gap

In case some of you haven’t seen the new variable gap spark plug

The gap opens up completely when the spark plug is pointed up and closes completely when the plug is pointed down!

For what it’s worth, every time I’ve seen this it’s on an Autolite plug. But that’s just my experience.


My replacement DENSO plugs for my Toyota come already gapped so you don’t have to do anything.

DENSO and NGK are the only spark plugs I would ever use. Even in engines which originally recommended something else, they always work well.

Turning it upside down seemed to have shined it up too … :wink: hmmm … maybe that’s the cause of bald men’s shiny noggin, hanging upside down too much.

I’ll bet it acts up driving on a rough road.

I use ACDelco in GM engines, Champion in Chrysler engines, and Autolite for the very rare occasions I work on a Ford.

Another reason not to flip your car. In case you needed another.

I remember those old Autolite commercials. In a Fonzi accent: “Heyyyy…we’re the Autolites!”

Something else to check I guess but yeah I just use AC or Champion or Briggs in small engines. I remember way back in the 70’s, my BIL always had Fords and had a spark plug problem that caused severe damage in his engine. I don’t know if they were Auto-lite or not but I suspect they were. He went round and round with them on the damage and finally got some compensation. It would make sense though if the electrode came off and bounced around in the combustion chamber.

I vaguely remember seeing a plug like that one time but it’s been so many years I do not remember the make. I was using mostly Bosch and NGKs at the time so it was likely one of those two.

As for Autolite, I’ve used them in my Fords for decades and have never had any problems with them. Not to say it can’t happen. Autolite probably manufactures billions of those things so a few failures are bound to happen.

As for Champions, the only thing I use those on are small engines and my Harleys; the latter coming from the factory with Champion produced but HD branded name on them. The plugs on my old flathead are air cooled and can actually be disassembled, cleaned, and put back together for another 50 years of use.

And they can be godawful expensive. About a decade ago someone bid a pair of NOS plugs on eBay up to 750 dollars with several dozen bidders.