spark plug gap

[toyota62]

Hi.
Spark plug gap the bigger the better or smaller the better?
Ex:1.1mm to 0.8mm?
Why OEM's using larger plug gaps on these day's?
Cheers.

 

[m2200b]

Hotter spark when it leaps farther leads to more complete burning and lower emissions. Most the gap jump is from early 1990s as cars went from carb to fuel injected.

 

[unDummy]

Bigger is better is you can fire that plug.

The gap can be increased because the newer cars have exotic plugs and better ignition systems.

The gaps don't change much(if at all) on fancy plugs in 100k miles of usage.

And multiple coils, coil on plugs, short plug wire runs, ....... increase the power available and reduce the power wasted.

 

[BlazerLT]

stick to stock gap, you don't need to tinker with it.

 

[acewiza]

I gap the copper plugs on my V8s a couple thousandths under spec so they run through the optimal range as they wear out.

 

[toyota62]

Set mine to 0.9mm from 1.1mm gap and running far better.Better acceleration.

 

[sprintman]

Buy NGK Iridiums the best plug you can buy and you don't have a 'gap'. Mine have done 80,000kms and still 'as new'. Think I'll screw a new set in soon just to see if there's a diffence.

 

[toyota62]

Hi sprintman.
I have installed Denso VK20 long life iridium spark plugs.
They are better than NGK's.
0.4mm centre electrode compared to NGK's 0.6mm centre electrode.
Also have 0.7mm platinum chip on the ground electrode.
This plug will last 100000kms easily.
$30 each.
Cheers.
Bob.

 

[mechtech]

For idleing and cruising, a wider gap can be used, and will help fire the leaner mixtures, under those conditions.
Problems arise when accelerating - there is more resistance to overcome, and the wide gap may misfire. You may not feel a 1% misfire when it occurs.
US automakers used gaps of up to 0.10" , then worked their way down, as they were problematic.
.040" - .060" is common, now.
If everything is in tip top shape, you can generally gap your plugs .002" -.004" wider than stock, with a benefit in some conditions.
At least go to the wider end of the factory spec.
Older ignition components, and frequent heavy acceleration, would favor a slightly smaller gap, to give some leeway and insurance.