Properly gapping plugs

[justinf89]

I just purchased new plugs for my 502 and the spec is .045. The plugs come gaped around .03. When I enlarge the gap by bending the rear of the ground, the surfaces are no longer parallel.

Is there a way to properly gap these? Take a look at the pictures below. I'm just using a standard flat feeler gauge but the gap on the outside obviously larger than the inside.

I was thinking about tapping it flat while the gapper is still in it to hold the gap.

The plug on the left is original and on the right was my attempt to gap. The plugs are ngk br6fs.

 

[Drew99GT]

Don't worry about it; as long as the gap is correct leave it be. You can see on the ungapped plug it's not perfectly parallel as well. It doesn't need to be.

 

[Eddie]

There is a tool that allows one to gap plugs and keep the electrodes parallel. Looks like a pair of pliers except for the plug end. I haven't seen one for years and probably only good for standard plugs like shown, but, not other types. Tapping it flat with a Gage installed will break the porcelain or seal.

 

[RF Overlord]

Agreed that having the ground electrode perfectly parallel is not important. I use a round-wire type feeler gauge and set the gap so that the gauge begins to drag when it's in the middle of the centre electrode.

Do not adjust the gap by tapping the plug on something...as stated you risk damaging the porcelain.

 

[KitaCam]

Most plugs today come PRE-gapped....if yours were supposed to be pre-gapped correctly and weren't, return them...do not attempt to regap them.

 

[slug_bug]

KitaCam, By pre-gapped, do you mean from the manufacturer? Or the vendor you purchased from?
If manuf. Does the manufacturer create different part numbers for the same plug at different gaps?

I'm just curious how most plugs could be pre-gapped to specific vehicles? Sorry if this is a newbie question, but, with so many different vehicles and engines it seems like a tremendous number of custom spark plugs/part #'s would need to be created.

 

[KitaCam]

Originally Posted By: slug_bug
KitaCam, By pre-gapped, do you mean from the [plug] manufacturer? Or the vendor you purchased from?
If manuf. Does the manufacturer create different part numbers for the same plug at different gaps?

I'm just curious how most plugs could be pre-gapped to specific vehicles? Sorry if this is a newbie question, but, with so many different vehicles and engines it seems like a tremendous number of custom spark plugs/part #'s would need to be created.


This.

 

[Whimsey]

Originally Posted By: RF Overlord
Agreed that having the ground electrode perfectly parallel is not important. I use a round-wire type feeler gauge and set the gap so that the gauge begins to drag when it's in the middle of the centre electrode.

Do not adjust the gap by tapping the plug on something...as stated you risk damaging the porcelain.


Guess I've been lucky these past 45 years. I always tightened up the gap by gently tapping it on a firm surface like wood. I also find that the circular graduated spark plug gap tool is more accurate. They're about $2 at parts stores and Walmart. That spark plug gap plier tool is nice, though not worth it for me.

Whimsey

 

[Merkava_4]

Originally Posted By: Whimsey
Guess I've been lucky these past 45 years. I always tightened up the gap by gently tapping it on a firm surface like wood.


I do worse than that -- I rest the ignition wire end on a 3/4'' thick steel plate while I tap the electrode with an 8 oz ball pein hammer. I may go back and forth with the gapper and the hammer 2 or 3 times until I get the gap perfect.

 

[Vikas]

The NGK plug number usually ends in -NN where the two digits gives the gap in milimeters e.g. -11 would mean 1.1mm gap mean .044 inch

 

[Tegger]

Originally Posted By: justinf89
Is there a way to properly gap these?

I must have posted this easily-found-through-Google YouTube video four or five times by now.



By the way, NGK does not recommend opening any plug gap by more than .008" from the way it was shipped. Buy the correct plug instead.