MTL_4runner

I give em a visual inspection (for any physical damage) on the Densos and NGK's.
......otherwise I install them straight out of the box.

deathrunner

does it really make a difference? i gap em too

dwa

I had the same question and e-mailed NGK. This was the response:

"When they talk about gap they are referring to single ground spark plugs.
The gap for the dual ground is measured between the insulator and the bottom
of the ground electrode. This spark plug is designed for anti fouling. If
you adjust the gap on these spark plugs the spark plug won't perform
properly. Again dual ground electrode spark plugs don't require gapping."

I asked for clarification re the measure being between the insulator and the bottom of the ground electrode and this is the response I got:

"The gap is read between the bottom of the bent part of the ground electrode and the insulator to the center electrode. These spark plugs are designed for anti fouling. When the insulation resistance is lowered by carbon deposits it fires across the insulator and breaks the deposit off. You can't adjust the gap on dual ground spark plugs. When they refer to gap, they are referring to a single ground electrode spark plug. This doesn't apply to a vehicle with dual ground spark plugs installed."

For what it is worth.

deathrunner

so that leads me to assume that you don't need to adjust the plugs with 4 electrodes.....good to know.

habanero

I'd still check the duals and exchange if the gap's wrong. It may be less likely that these would get bent but too many people handle plugs before we buy them and many don't think a thing about sticking them back on the shelf after dropping them. The singles I always check and adjust if need be. For a few extra seconds of time to insure I don't have to pull a plug it's not worth not doing it.

pat161

I always check them, why wouldn't you?

spyne

I've gotta gap them. Who knows how many times they've been dropped during shipment, banged around in the parts room, etc.

kyle_22r

platinum 4 plugs are a waste of money IMHO. most guys like NGK or denso plugs for toyota engines, though i've never had problems with autolites either(i run them in my trail truck)

mach4

I use NGKs and Densos and always gap them.
FSM and owner's manual says to gap em.
There was a post a while back where someone had changed out the spark plugs and started getting knocking.
He pulled all the plugs out and one of them looked like it was misgapped.
The spark plug was replaced and knocking went away.

Now, there could have been something wrong with the inside of the plug or it could have been damaged in some fashion, but why take the chance when gapping is a simple procedure.

getitdone

Yep, he's right.

Tacoclimber

I always check mine...

V_Runner

NGK's pregaped or ungaped work fine...BUT YOU SHOULD ALWAYS GAP THEM...gapping them makes them fire hotter or colder and depending on the enigne they should be gapped correctly for BEST preformance...

WV Jay

same here

srpage

I always check em first and generally the gap is correct.

It seems foolish not to at least check the gap before you install em.