A short how to video on the proper procedure to gap a spark plug using two different style spark plug gapers. Please subscribe to our channel and find us on Facebook @ facebook.com/southmainautorepair

9 thoughts on “How to gap a spark plug”
  1. Avataaar/Circle Created with python_avatars Piper Cessna says:

    Damn, after 50 years I found out what that "T" shaped bit on the gap tool did. Thank You Eric! (I'm sorry….Dr O!) 👍
    First tools I acquired when I got my first car was small flat head (slotted) screwdriver to open spark plug gap, spark plug gap tool, feeler gauge, points file (electronic ignition killed their sales), spark plug socket and a adjustable spanner (shifter) which was used to close the gap when it was opened too much. It was used to tap the electrode on the flat part of the tool. Wheel brace came next even if the car still had it's tools. I used to change tyres (tires) and fix punctures for several years as my after school & holidays job and I preferred to spin the wheel brace than struggle with those stupid lug nut bars when changing wheels.
    Also had a theory that if the plugs oiled up then one would open the gap in the belief the the spark would be hotter (because it had a bigger gap to jump) and therefore would burn the oil off the plug. No idea if that really worked because I was not a mechanic but the plugs didn't seem to oil up as much however that may have been just wishful thinking of the young and ignorant. 🤦‍♂

  2. Avataaar/Circle Created with python_avatars Tom Oakhill says:

    What?!? Why so few views. This is short & sweet, Barely 3-a-day since published.

  3. Avataaar/Circle Created with python_avatars Dewayne Maiden says:

    Since I started as a kid messing with cars I always thought that was 4 the keychain. And they say an old dog cant learn new tricks

  4. Avataaar/Circle Created with python_avatars Sam Valentine says:

    One footnote on gapping spark plugs when you have a spec range – as Mr. O said in the video, the plugs he was working with was .042" to .046" thousands – that's the range. With plugs, one is wise to set the gap on the smaller of the range (closer in this case to .042"), the reason being that the plug will stay in spec longer. As spark plugs wear, the gap increases, so a plug gapped to the smaller dimension (.042") will get larger as the plug wears, and will get closer and closer to the .046" in time. A plug set to the larger side of the gap range will go out of spec sooner as the plug electrodes wear, the side electrode and the center.

    One would use the opposite with ignition points on an older traditional non-electronic ignition. For example, if there was a range of .018" to .012", you'd normally want to set them to the larger gap of .018, because points usually get closer together as they wear. The rubbing block that rubs against the cam lobes wears down, and as it does, the point gap decreases. Hence the reason why they give a small amount of light grease to wipe on the lobes – this makes the rubbing surface last longer – therefore keeping the ignition in tune for a longer period of time.

    Love your videos, Dr. O! Keep 'em coming!

  5. Avataaar/Circle Created with python_avatars David Crandon says:

    Incorrect about the round disc and determining the gap. You do not take an average because the electrode covers about 0.003 or 3 markings as you state. You take the widest marking. That is the marking the leading edge of the electrode first touches and stops. The electrode is not touching the width of 3 marks. It is only touching the "first" or widest indication marking at the leading edge of the electrode. In the video, that would be 0.051 before modifying the gap, and 0.045 after gaping it.

  6. Avataaar/Circle Created with python_avatars jimbola77 says:

    Excellent I never knew what the hole was for thank you you are an Excellent mechanic!!! thumb's up….

  7. Avataaar/Circle Created with python_avatars Geo Jor says:

    thank you…

  8. Avataaar/Circle Created with python_avatars johnwrench4speed says:

    I just learned that one should not use the ring type plug gap tool on any coated (i.e., platinum, etc.) spark plugs because it will take the coating off.

  9. Avataaar/Circle Created with python_avatars Handy Daddy says:

    Another awesome video. I have one of those "coin" type tool and had no idea until now that that hole is for expanding the gap. THANK YOU!

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