runner264

I just finished the plug change. I did open it up to .032. This is what the plugs were gapped to by JDM on the install last year. Seems to be idling fine but I'll keep that in mind. I did tighten them down a bit more because 9lbs seemed way too little although it's the spec. Easier install than I thought. Running well on my initial drive.

it did take over 30lbs to break them free, so I am assuming they were tightened by hand.

bingo2

Here's another reference for torque values; http://www.ngksparkplugs.com/tech_su...e.asp?mode=nml

I'm not running much boost on my litle M90, just 8lbs and I gap the plugs at .040 with no issues. I tried .032 and .035 and experienced some idle issues as well.

runner264

After taking a much longer ride I can feel the difference in performance. I knew I had lost some power over the past few months. Didn't really know what it was. I guess changing the plugs after a year on a S/C engine is a must. Funny thing, my friend heard my car going down the road and he said it sounded different and better. I am assuming Superchargers are rough on spark plugs. Has anyone else experienced this? I am also thinking maybe a change even sooner next time. I put on about 8k since the initial install

I did see the NGK plug specs but it didn't show the torque spec for the 12mm conical taper plug. I went with 20lbs because it is what felt right to me.

goose5

Also add a smear of brake caliper silicone caliper grease/dielectric compound(the thick stuff) in the coil boots...

kpd1031

Runner, I absolutely agree that 9 lb/ft and 25 lb/ft is a huge difference. It can be the difference between stripping the head or breaking a plug. Anyone who suggests using the old torque spec on the new head with out knowing the proper values is crazy, I don't care how many posts they have. Be guided by these forums, but do your research.

Simon1

Reading the thread makes me want to go check my plugs. I have been bad and haven't looked at them in a while (4 months or so).

The guy who built my motor wants the plugs changed every 5000 miles, depending on usage and if I ever have detonation, I change them. I don't keep track of the mileage, I just check them often enough to see when I get the detonation or heat marking on the porcelain, or the electrode gets yucky.

I keep an entire set in my track bag, gapped and anti-siezed. It used to take me 10 minutes to change all plugs but now with the KB, the intake makes it tricky on the passenger side.

I run the HTOs and have had great success with them.

runner264

I did use the dielectric grease on the boots. They came off and went on very easily.
After changing the plugs and feeling the difference, I plan on changing them every 5k as Simon's mechanic recommended.
Chaning the plugs was very easy. I recommend getting the 9/16" spark plug socket with the 6" extention built right on it. Then you will need another 4-6" extenion to get out the back plugs. Just makes things easier. Also recommend compressed air and blowing out all debris around the spark plugs before removal. You will have dirt and junk in there and you don't want that to fall into the chamber.

Riptide

Seems pretty ridiculous to have to change plugs every 5000 miles. Some people go longer than that on a fill of oil. WTF

runner264

I would tend to believe that the added pressure and increased fuel would tend to wear out the plugs more. I know for a fact most are tuned to dumped in more fuel at WOT and a richer A/F ratio. I would think this over time would burn out the plugs more. That's just my unprofessional opinion. When I pulled my plugs they looked okay but when I installed new ones that were exactly the same with the same gap it is running better. Not to say it was running bad before but there wasan improvement.

Simon1

I agree. But it's cheaper to buy a one or two sets of plugs every year then to get a new motor. I would hate to replace a motor because of alck of maintance. Running lots of timing and 15 PSI is pretty rough on plugs.