M109 Rider Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
49 Posts
Discussion Starter · #1 ·
running ngk iridium 8 at 5000 foot elevation should i stay stock gap?have some backfire on deceleration:dontknow:
 

·
Registered
Joined
·
4,485 Posts
No, you are right. You aren't suppossed to mess with the gap on them; they are pre-gapped.
that is what i was saying just in a round about way. i think the only spark plug that needs gapped now a days is like a old autolite type plugs if you dare run those in anything. for like old school applications.
 

·
Seasoned Member
Joined
·
7,635 Posts
someone please chime in if im wrong here but arent iridiums already gapped per application??
Yes, they are. But you should "check" the gap out of the box anyway. Especially if you received your plugs "loose" in the shipping box, like the last set I got from DLP (2 were out of the NGK boxes, bounced loose around the shipping box and the factory gap got messed up in transit). Gap should be .024"-.028" (.6-.7mm). The reason NGK discourages "adjusting" the gap on iridium plugs is that you will most likely either break/damage the center electrode or misalign the ground electrodes to the center electrode. Same goes for multi-ground plugs like the OEM plugs. Again, there is a difference between "checking gap" and "adjusting gap". It is recommended that you always "check" the gap of new plugs. It is not recommended that you "adjust" the gap of iridium and multi-ground plugs. Check NGK's FAQ page on iridium and multi-ground plug gapping... says the same thing. :bigthumbsup:
 

·
Radio Active Member
2007 Candy Sonoma Red
Joined
·
22,864 Posts
The backfire, or popping, on deceleration has nothing to do with your plugs. You either have a leak in the exhaust or your PAIR valve needs plugged. Popping is caused when outside air is admitted into the exhaust.
 

·
Registered
Joined
·
49 Posts
Discussion Starter · #7 ·
pre gap was wrong

they are gaped at 32 I did mine at 28 my buddy did his at 27 no back fire runs smooth getting better gas millage to,,we tried running at pre gap didnt runs as good ,back fire to thats what works for us
 

·
Registered
Joined
·
1,458 Posts
I've seen a couple that are more around .015 on one side . Always check them. They get dropped in the factory and bumped in shipping so always run a feeler gauge across them. I got into the habit years ago of metering out plugs as well to make sure that they were all good.

I run them at .025 and that's about where they all seemed to be gapped at for me.
 

·
Registered
Joined
·
2,703 Posts
You can do the Pair valve block off plates or the marble mod like I did and it took all the popping on deceleration away.
 

·
Registered
Joined
·
39 Posts
Before gapping your plugs get a micromiter that you trust and check your gap setting gauge. I thought what the hell the two were together and checked it... the cheepo gap setter was way off and I had been using it for years.

Getting a good tool right off the bat saves time and money.
 
1 - 10 of 10 Posts
Top