Spark Plug Torque

jdallen · Posted: December 11, 2008, 8:26 pm Post subject: Spark Plug Torque

The yammie manual says 14 ft/lbs, but the NGK package says 18-21ft/lbs for aluminum heads, gasket type....should I use 18-21?

xsjohn · Posted: December 11, 2008, 8:32 pm Post subject: Re: Spark Plug Torque

Right or wrong I just snug them........

xsjohn

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

mee too. never used a torque wrench on them ever.

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

Yeah...DONT use a torque wrench...

Thats good advice given to me and by me many times...

You "could" have a damaged thread ..that gonna be fine for ever unless you put 14 ftlbs on it!..

I use a plug socket with my "fist" one side touching the actual extension bar..so you've only got a hands width of leverage..(I know..some pretty big hands out there LOL)..

ost important thing is to use NEW plugs or NEW plug Metal O-rings as soon as those rings are squashed thats it! No need for any massive torque..

jdallen · Posted: December 11, 2008, 9:19 pm Post subject: Re: Spark Plug Torque

I just changed the plugs in my car today b/c of some high speed stuttering and 3 of the 4 had backed themselves out. 1 was so loose that I didn't even need a socket wrench to loosen it. Also, the 3 loose ones all had the end cap stuck in the cable plug. They were Autolites.......I don't think I'll get those again!

anyways, that got me thinking about proper torque.

Retiredgentleman · Posted: December 11, 2008, 9:31 pm Post subject: Re: Spark Plug Torque

18 to 21 ft/lbs is too high. Haynes manual says 14.5. If you want to use a torque wrench, try using 12 ft/lbs and I'm sure it will be fine. The idea is to use the least amount that will get the job done.

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

Indeed...definatately the least at least ? LOL

xsjohn · Posted: December 11, 2008, 10:30 pm Post subject: Re: Spark Plug Torque

Could be almost....maybe

xsjohn

gordo · Posted: December 11, 2008, 10:50 pm Post subject: Re: Spark Plug Torque

All your answer's are proper,just a little more than snug.Jake is correct in saying that new plug's & gasket's.I just tighten until the gasket crushes, then a little bit more.Torque is probably about 10- 12 lbs/ft.It is a "feel" that develope's over time.Haven't had one back out yet.Thanx to all you guy's Jake, xsjohn, R.G.,..Also, a little anti sieze on the thread's help's.I said a little!!!The stuff will be runnin' down to your side cover's.

metalredneck · Full Member Joined: Aug 04, 2008 Posts: 308

Yep. More of a "feel" thing.

xsleo · Posted: December 12, 2008, 6:58 pm Post subject: Re: Spark Plug Torque

i always spin them in with my fingers till snug, then turn another 1/4 to 1/2 turn. anti sieze use very sparingly. it acts as an insulator, makes plugs run hot. gums up in the threads, need to run a thread chaser in the threads occasionaly to keep clean.

jdallen · Posted: December 12, 2008, 9:16 pm Post subject: Re: Spark Plug Torque

thanks men. here's what NGK says....

Torque is one of the most critical aspects of spark plug installation. Torque directly affects the spark plugs' ability to transfer heat out of the combustion chamber. A spark plug that is under-torqued will not be fully seated on the cylinder head, hence heat transfer will be slowed. This will tend to elevate combustion chamber temperatures to unsafe levels, and pre-ignition and detonation will usually follow. Serious engine damage is not far behind.

An over-torqued spark plug can suffer from severe stress to the Metal Shell which in turn can distort the spark plug's inner gas seals or even cause a hairline fracture to the spark plug's insulator...in either case, heat transfer can again be slowed and the above mentioned conditions can occur.

I think the key will be to torque it to the "least at least" and just check it frequently.....not like my car which get's checked every couple of years.

jimmythetrucker · Full Member Joined: Mar 12, 2008 Posts: 1283

In all of my life the only time I ever had plugs come loose on me was in an old Ford six-banger. In that engine the plugs came loose repeatedly and I couldn't figure out why. Then I paid attention to the fact that the plugs (Autolites) in the specified heat range came without copper crush rings, and the manual for that engine listed a torque spec for the spark plugs.

So I used a torque wrench to install a new set of plugs. They came loose anyway. By and by I got smart: I switched to NGK plugs in the correct heat range. They came with copper crush rings on 'em. I installed 'em with a 3/8 ratchet, wrist tight. I never had any more trouble with loose plugs and I never bothered with a torque wrench on spark plugs again.

I don't know if the problem was Autolite manufacture or the fact that Autolites in the correct heat range came without the crush ring. I just know that switching to NGK plugs fixed the problem.

xsjohn · Posted: December 13, 2008, 2:18 am Post subject: Re: Spark Plug Torque

That's all I use is Autolites in mine......maybe I should epoxy them in ... Shocked

xsjohn

jimmythetrucker · Full Member Joined: Mar 12, 2008 Posts: 1283

John -- Autolites wouldn't run in my old XS1100. I put one set in and didnt get 40 miles before one of 'em fouled.

As for Autolite plugs coming loose in an XS-650 -- you say you have no problem with 'em. But I bet the ones you use come with crush rings on 'em, don't they?

xsjohn · Posted: December 13, 2008, 5:31 am Post subject: Re: Spark Plug Torque

Crush rings for sure...........now that I have changed the tuning the bit hotter heat range is good.....I use the Autolite 64 which is a BP6ES......Autolite 63 is a BP7ES.........I can't tell the difference between the Autolites and the NGK.....If I could I spose I would use NGK........plugs seem to last forever in mine.......just change them when I get bored every couple of seasons sometimes.....Heck I have had these 64's in there forever in there it seems......different tuning and the plugs are clean before I get to 5th gear and don't get white on the express........guess I am done with that issue and it runs dead smooth.......compression ratio 8-1...@...135lbs................and 55-60mpg..........

xsjohn

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