Spark plug gap question.

[wtd]

I own two 98 chevy trucks, one with a 7.4L and one with a 5.7L. I've read some things on the internet that suggest that both of these engines will run better with the spark plug gap set at .045 instead of the factory .060. Has anyone else heard this for these engines and has anyone tried this out.? Supposedly this will enable the engines to idle smoother and won't be as hard on the ignition system. Thanks.

Wayne

 

[paulo57509]

Gap the plugs at the factory specified setting. The ignition system was designed for plugs with that wide a gap.

If the specs list a range (like .038" - .042") gap them at the lower end of the range. As the plugs wear the gap will widen.

 

[Gary Allan]

What's he got to lose trying? If you're into the labor of regapping them if you lose economy, gap them .050-.010 closer ..and see what happens.

 

[mcrn]

I have an 03 GM with the 5.3. I have had the same issue. I have not changed mine yet but it seems GM recommended two different gaps. One being for factory plugs and the new gap being for platinum or Iridium. IIRC. Please check this out for yourself before you take my word for it. My truck says .060 under the hood but even when I search for plugs online most of them come set at .040.

 

[ATS-V]

I like to close the gap on some engines as it wears it will open the gap anyway, so in theory you get longer service life. On a standard plug I subtract 0.010'' and half that on a plat or iridium. Also in theory, a small gap is a slightly hotter spark. Most manufactures run cars way too lean at idle for emission in which case misfires are normal but a smaller gap will help in many cases.

 

[wtd]

Thanks for the replies. I think I will try closing the gap and see what happens.

Wayne

 

[mechtech2]

Engines like the most gap as possible.
This is always the best choice.
But what is the widest gap that will not ever misfire?
Obviously, it varies with different engines and set ups.
With no other information, use the widest factory gap .
Often cars are best with a bit more gap than this.