Hello

I'm coming up on 5 yrs on my 2004 sunfire. 68,000 Kms.
I bought new platinum spark plugs.
The gap should be 0.042"
2 of the plugs have a gap of 0.041" in one pack and the other 2 have a gap of 0.044" from the second package.
Is this good enough or should I try to bend it slightly to get it closer to 0.042" ?

Thanks

Walt

You should always gap plugs yourself. ALWAYS



I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26

agreed, always gap them yourself, just dont get too hasty and break them, ive done that before and it sucks when you pay 8 bucks a plug

Assuming that you've bought OE style plugs - be VERY careful when checking the gap, as it's very easy to break off the small "dot" of platinum on the side wire. Many of the side wires on the newer plugs are very hard to bend - so being accurate within .002" is probably close enough. You're not likely to get it much closer than that without risking damage. With the double platinum, that gap will remain essentially the same over the lifetime of the plug, so such a small difference isn't likely to make a difference.

I'm not sure how the Ecotec module works internally, but if it uses 2 coils, then 1 likely fires 1 and 3, and the other 2 and 4. If this is the case, I would make sure that 1+3 match, and 2+4. Not that it's likely to make much difference, but if you're being picky...

Those original plugs would likely be just fine for more than double their current amount of usage. I've known people to run them in excess of 200,000km before running into problems. I changed mine early around 120,000km, but gas mileage didn't change a bit, and there were no indications of misfire before anyway. For some reason I just figured that it was probably "time" (most likely like yourself), when in actuality I should have just stuck with GM's recommendations and saved my money for a while.

One thing I found unusual was that GM specifically recommends against using any type of anti-seize compound on the plug threads. I've always used this on my own cars - but they must have their reasons. Maybe something about the head design in the Eco can allow them to back out more easily? I'm not sure why for sure, but I would probably stick to their recommendations, as long as you're using AC Delco plugs. Other plugs may not have the same corrosion resistant coating on them, and this could alter the recommendation somewhat.
John

Hey John

I thought of using anti seize, so I'm lucky you pointed out that I shouldn't.
I noticed that the plugs do not have a washer. The instructions on the package say that once seated I should turn the plugs 1/16 of a turn to secure them. There is a taper at the end of the thread which probably mates with a taper at the top of the spark plug hole. (If you use plugs with washers, usually it's about 1/4 of a turn or there abouts.)

I figured the plugs in there are OK but I wanted to change them just in case. If they look OK, I'll keep the new plugs in there longer.
This is another job I'll do over the holidays

Thanks again for the advice.

Walt

I (firmly) believe that spark plugs should be tightened using a torque wrench to the manufacturers specification. The argument against using anti-seize compound on the threads centers on the concern that it will act as a lubricant and the specified torque will then be too much. As a result, most modern spark plugs come pre-coated allegedly to eliminate the need for anti-seize or the spark plug shell itself is made of a nickel alloy. I've seen a recommendation that if the plugs you're going to use are plain steel, then use anti-seize and reduce the tightening torque by 30-40%. That being said, I always use a trace amount of anti-seize compound on plugs I install. I guess this goes back to my Chevy Corvair days when coated plugs didn't exist, most mechanics preferred to not work on aluminum engines and torque wrenches were optional. (I got pretty good at installing Heli-Coils and Keen-Serts.) Good luck and take care. - Mark

I never gaped my plugs, cause i got 'hasty', but the car runs just fine, even smoother than before, i only had 96 000 on the old plugs.

Used NGK iridiums. without any anti-seize either. my stock ones had no anti seize, and even they were kinda hard to get out.

Maybe i'll take em out tonight and chek em