I have always gapped my spark plug within the factory specs. I recently changed the spark plugs in my Ranger and after I had removed three from the right side (the tough ones) I realized I left my gapping tool at my shop with my race car. The minimum gap is spec'd at .062" so I decided to use a 1/16" drill bit to gap the plugs. The next day I measured the the drill to make sure it was right and it was .059". I forgot drills are a little under sized.

Now my question is: Is this gap being .003" under the spec really going to have any effect on the engine performance? It is running just fine but I have not gone through enough gas yet to determine if it has effected my gas mileage. Could it possibly effect emissions?

When I put an electronic ignition on my race car it was recommended that I increase the spark plug gap to around .035" or more. When I ran it on the dyno, the results showed that a .025" gap gave better horsepower.

I don't want to change the gap because it is too much trouble but I just wondered if anyone had information that a .059" gap would give me problems.

 

I wouldn't worry. Your talking about 3000'ths of an inch. Pull them in a year & check the gap. I highly doubt anything has changed. As to performance & mileage? Plugs are designed to operate within a "range" of gap. Your well in that gap.

Robin...

 

Gapping is slightly more important on the DIS ignition we have because two plugs fire simultaneously and they are in series with one another.

However, the difference here amounts to 5 precent or so and I'm not sure you have anything to worry about.

 

Thanks guys. That is along my same line of thinking but wanted to find out if anyone knew of a valid reason to go to the trouble of going back in and reseting the gap. I feel confident now that they are OK as is.