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Is gapping spark plugs important?


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welcome to USMB SDT!

 

no need for a torque wrench on the spark plugs. just make sure the engine isn't warm when you remove or tigthen them. the threads are aluminum and strip easily.

 

as for the gap - that shouldn't be ignored, they should be gapped to spec's when installed. the gap should be in the owners manual if you have it or check the underside of the engine hood - often it's printed on their somewhere.

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I changed my spark plugs 3000kms ago. I didn't use torque wrench etc just tightened until they all felt tight enough, is this ok?

 

What do the clearance on spark plugs mean and how does it affect performance?

 

thanks

 

How tight is "tight enough"? Overtightening or undertightening will damage the threads. You could guess at it, but if you're using a long wrench you could easily overtighten...conversely, if you use a small wrench you could easily undertighten. I dunno, a $10 torque wrench is cheap insurance you dont damage your head.

 

Yes you need to gap the plugs. The clearance is the distance the spark needs to jump across...out of spec clearance stresses your ignition system and gives worse gas mileage. Easy to buy the $3 gapping tool and get it within spec.

 

Also, consider applying a small amount of anti seize compound to the threads upon inserting.

 

Hand tighten to get threads started to prevent cross threading.

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tsk tsk tsk gross, you were almost correct.

 

 

Todays plugs come pregapped from the mfg, becuase the porclin around the tiny electrode, as well as the the electrode tab can be very brittle, and easily damaged if you try to gap them (especially with exotic metals). Do check the gap when you get them, but if they are the wrong gap. you may have gotten the wrong plugs, or they may have been dropped. a very slight tweek is possible, but anything beyond that may be risky.

 

 

 

nipper

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I changed my spark plugs 3000kms ago. I didn't use torque wrench etc just tightened until they all felt tight enough, is this ok?

 

What do the clearance on spark plugs mean and how does it affect performance?

 

thanks

 

Usually the higher the performance engine, the smaller the gap. As the air fuel mix is compressed, the higher the compression, the more resistance there is for the spark to jump the gap. But the downside is the smaller the gap, the easier they may foul. Thats why there are differnt gaps for different applications.

 

http://www.ngksparkplugs.com/techinfo/spark_plugs/techtips.asp

 

nipper

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tsk tsk tsk gross, you were almost correct.

Todays plugs come pregapped from the mfg,

not in my experience. not all NGK's come pregapped. i'm not sure what or why, but i do know i bought a set a week or two ago that were not gapped out of the box, and that's not the first time. i'd say more often than not they are not gapped. it is annoying that some are and some are not, but most i'm buying are not pre-gapped. of course who knows, WV is still in the 50's in many ways, maybe they send all the old stock plugs here, i never use smileys but here's my tribute to poor WV:rolleyes: :rolleyes: :rolleyes:
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not in my experience. not all NGK's come pregapped. i'm not sure what or why, but i do know i bought a set a week or two ago that were not gapped out of the box, and that's not the first time. i'd say more often than not they are not gapped. it is annoying that some are and some are not, but most i'm buying are not pre-gapped. of course who knows, WV is still in the 50's in many ways, maybe they send all the old stock plugs here, i never use smileys but here's my tribute to poor WV:rolleyes: :rolleyes: :rolleyes:

 

Maybe they are matching the teeth?

 

:grin: :grin: :grin:

 

nipper

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what really gets me is that someone from NY is cracking those jokes. it's normal for adjacent states to make fun of each other, but WV has a reputation that's quite widespread.

 

ouch ..... that just hurt

 

 

painful pun, just painful.

 

 

:clap:

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Always, always use a torque wrench when installing spark plugs. Yeah, I installed spark plugs "by hand" back in the day, but a torque wrench is the only way to go. Too tight, and you coud strip the threads in the head. Too loose, and the engine could "spit" the plug out and ruin the threads. Either way you have a considerable problem that easily could have been avoided.

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  • 4 months later...

So I'm doing plugs for the first time today with a buddy of mine who is a BMW guru. Anyway, we differ in opinion. So I'm looking for yours.

 

My view:

1. Subarus (like most Japanese cars) require NGKs. No question. I've had misfires before due to Bosch plugs that the previous owner installed. No good.

2. As the car ages you should install higher grade plugs. Not necessarily iridiums in a car like a 2.5L Legacy, but platinums. And that goes for all cars.

 

 

His view:

1. You can put any plug in any car.

2. You should always put the standard, stock plug in. Anything else is a waste of money.

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You are rtight on #1, he is right on #2, especially on subarus. Too hot a plug can cause ping. I cant even call that hotter plug as the car ages an old wives tale as i never heard of it before.

 

SUbarus waste spark ignition requires balance and is desghned with a specific plug in mind.

 

 

Alos its been proven over and over, fancy plugs dont so anything. Its all psychological, as all you need is one hot spark to fire the fuel air mix.

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I use the Bosch Platinum plug, the least expensive model with the single electrode (the hooked portion). These plugs don't get gapped. I have 20K miles on them, and they run great. Yea, I have read here that Subies require NGK plugs. I installed the Bosch plugs before joining this forum. No complaints about Bosch plugs! They don't cost an arm and a leg, like other plugs do.

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I ended up getting Champions as they were about $10 cheaper per plug than the NGKs. I had never heard of using them in a Subaru before, but the owner's manual reccomended them.

 

Also, last time I had the plugs done at the dealer. I looked at those plugs today and they had a gap of .040. Specs call for .044. Interesting.

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My opinion is you should really return those lawn mower plugs and go get some NGK's! Champions are junk and I've never heard of a Subaru owners manual saying to use them. There is a reason you don't hear of them being used in Subarus! But you can disregard this as well, but I have a feeling you'll have issues later on with them! Good luck

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thats kinda like the guy who torqued the head gaskets Hella Tight.......

 

you sir, should take those plugs out and put NGK in.

 

When, and i know you will, have a problem with something, i will try and remember to give the same advice then.

 

No way, if you care about your car even in the very least bit, would you dare put champion plugs in there. RANt done

 

ps, your justification of they were 10.00 cheaper per plug than NGK is false.

Oreilly, Autozone, etc, NGK price is 1.53 per plug range to 2.12 per plug....I don't believe anything you have said for reason.

 

 

 

I ended up getting Champions as they were about $10 cheaper per plug than the NGKs. I had never heard of using them in a Subaru before, but the owner's manual reccomended them.

 

Also, last time I had the plugs done at the dealer. I looked at those plugs today and they had a gap of .040. Specs call for .044. Interesting.

Edited by bheinen74
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I don't believe anything you have said for reason.

 

Really you were with me at Napa this morning? Funny, I didn't see anyone else in the store.

 

My opinion is you should really return those lawn mower plugs and go get some NGK's! Champions are junk and I've never heard of a Subaru owners manual saying to use them. There is a reason you don't hear of them being used in Subarus! But you can disregard this as well, but I have a feeling you'll have issues later on with them! Good luck

I dunno, car is running better than ever with properly gapped plugs. Don't plan to keep it long enough to justify spending $12 a plug when I don't have to. No to mention that my NGK plugs only lasted 30,000 miles. That is far from spectacular. I'm not convinced that they are all that great.

Edited by Slegacy96
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My opinion is you should really return those lawn mower plugs and go get some NGK's! Champions are junk and I've never heard of a Subaru owners manual saying to use them. There is a reason you don't hear of them being used in Subarus! But you can disregard this as well, but I have a feeling you'll have issues later on with them! Good luck

 

 

2.2L Have Champions listed one choice of sparkplug. They also list NGK and Nippeondenso. 2.5 are NGK's.

 

And I do side with you. At one time Champions were great plugs, but as emission controls got tighter, they seemed to degrade in performance.

 

Maybe they only work well runing in a rich enviorment.

 

nipper

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My opinion is you should really return those lawn mower plugs and go get some NGK's! Champions are junk and I've never heard of a Subaru owners manual saying to use them. There is a reason you don't hear of them being used in Subarus! But you can disregard this as well, but I have a feeling you'll have issues later on with them! Good luck

 

My 1999 Forester was delivered with factory installed Champion plugs. I like NGKs, but frankly, any quality plug will work. A spark plug is just marginally more sophisticated than an air valve cap.

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