whats a decent gap to run on spark plugs? i had plug that were 1 step colder but my tuner had em gapped at like .026. i think that would kinda close for a stock motor considering the stock gap is supposed to be .043. ive seen people w built motors gapped at .030. my main concern is that my driveability tanked, and i was gettin all kinds of codes for misfires and rich codes. i changed em to stock plugs and its runnin alot better.

 

Idk if this is relevant but DON'T gap iridium plugs. the tip might break off.

 

If done correctly there should be no problems. At the moment I have my iridium plugs gapped to .028 and running 20psi. Two step colder plugs btw. Not sure changing the gap any closer will provide any more power in my case but it would be nice to test out different plug gaps on the dyno just to see.

 

When running a colder plug, you may encounter a misfire code but it can almost be expected especially during cool weather upon start up. You have to understand the purpose of running a colder plug, running stock plugs on a boosted application isn't a good idea. It could cost you a motor. I know it will idle better with stock plugs because they run hotter, but under boost the electrode will get too hot... detonation can occur.

Gapping is the same thing, it is give and take . I have personally seen 20whp plus gains just from closing gap .002 at a time. Ideally, a large gap would be best for smooth driveability.... but spark blowout can occur under boost.

Crush.... you are definitely giving up power for driveability running a 28 gap at 20psi.

Oh , I gap Iridiums all the time. If you wack the strap hard enough to where the tip breaks .... Id say you shouldn't be touching cars.

 

we have been gapping iridiums since boost was introduced to our cars my friend. just because the valve cover says that doesnt make it true.

 

i had 2 step colder iridiums, .30 gap on stock motor worked out fine.

 

i used 1 step @ .32 never had any issues @ 10psi

 

right but what im getting at is the fact that they were closed off to around .026. dont u think thats a bit close for a stock motor @ 10psi? i was thinkin somewhere around .032-.035 would be a decent gap for boost and driveability.

 

they were also 1 step colder. i threw in factory plugs to make sure they were fouled. sure enough, it cleared up. i do have a new set of 1 step colder plugs, but idk if i should gap em at the same gap as my tuner did.

 

i ran .32 on a stock motor @ 10psi.

 

FYI, you can buy ND or NGK plugs pre-gapped to .032". If you need to further decrease the gap, it's better to start at .032 than .044". Just buy the same plug without the -11 suffix on the part number. -11 indicates a gap of 1.1mm (.044") and no suffix or -8 indicates a gap of .8mm (.032").

 

fred you have a host of useful information.

 

Many people I know would say "useless information" so I thank you!

 

I know how you feel

Sent from my DROID incredible

 

It's their loss. Most people I know think that you can't even work on modern cars but here we are modifying them to performance and economy levels that 60's muscle cars never acheived. My 68 Camaro 396 SS ran the 1/4 in 14.26 and got 10-15mpg. My 87 Mustang GT ran 14.7 and got 15-24mpg. My 08 XB runs 14.33 and gets 22-30mpg.

BTW, my own experience with plugs and boost has been that NGK iridium IX work great and "copper" (nickel) plugs do not. At 6 psi a gap of .032" works great for me.