Spark Plug Torque--Not By Hand!

[cpostis]

For a copper gasket what should the condition of the metal be in for it to seal properly?

Does anyone take the time to heat treat (anneal) their copper gaskets to ensure they seal and transfer heat as they are supposed to?

Stuff on the surface might appear to be simple but in reality it is not always so. There is a lot more going on in a spark plug than simply making a spark.

Interesting Boscoe! I just had top look this up.

https://www.youtube.com/watch?v=YSRx3k8domw

That Kevin guy seems to know his "Old School" stuff!

Early in my career as an apprentice, I had to anneal large diameter copper air conditioning pipe (over 3") to bend at an odd angle. This was in a new temple with a $2 million dollar hardwood ceiling that had the have the pipe concealed in minimal space allowed. The old time journeyman should me how to do it. We had two men on the pipe with rosebud torches heating them up red hot then bending the pipe while it was red. Some bends kinked. I got reamed out by the journeyman. He got peed, off left me alone with another apprentice and we heated the pipe, quenched it and used a bottle jack and a rigged a "wood die" to the angle we needed. Not a kink in the remainder of the custom bends.

The journeyman bought us lunch and then a few beers after the day.

[Jason2tpa]

I's something how some people can solve "Rubiks Cube" in moments and others can't ever?
On NGK "crushable gaskets" are three stamped flats in the ID (others have four). These must be lined up in the spark plug threads properly in order to unthread from the plug. Here's a video that shows the gasket being removed and contains ferrous metal (click on image).

[IMG]15375246_1736673533326855_2560081111514349568_n by Charles Postis, on Flickr[/IMG]

I normally don't worry about the gasket, but if you remove and re-install several times, why not change the 15 cent gasket? You guys change your gear case drain screw gasket every time, don't you?

Now, do you guys know the most important role in a "crushable gasket"?
Heat transfer!
Take a gander at this.

https://www.ngk.de/en/technology-in-...and-heat-flow/

40% of heat removal from the cylinder to the head is through the "crushable gasket". It increases the surface area of the transfer area. I know you guys always install your plugs and gaskets oil free, clean and dry, right? The hotter the plug range the more critical the heat transfer area is.

Very interesting read. I had thought the most important role of the crush gasket was as a seal. Now you have to wonder, if you're reusing a crush gasket then it no longer has the preformed corrugated surface area to transfer heat. So this heat that is normally transferred to the gasket is going somewhere else. Replacing the 15 cent gasket when reusing plugs doesn't sound like a bad idea.

[Jason2tpa]

Seems like I remember oil seepage around plugs before on 2 strokes.
I do not believe you would need to worry about leaking compression thou

This i can confirm. I installed new plugs after purchasing my engine. Few months later I noticed a brown oily discharge coming from the spark plug ports. I attributed this to 2 factors...the spark plugs were not seated tight enough (despite the hand tight then wrench snug technique), and second the high amount of idle time.

No oily discharge has been seen since I tightened down plugs another 1/2 turn in, and the engines idle time has not changed since then. Which kinda brings this thread back full circle. Seating plugs to specified torque is worth practicing.

[noclutch]

Cross post fromTHT- opinions please

Engine - F300, 350 hours

Last night when replacing mine ( because I'd de-carbed/shock treated) I found that the dealer had greased the threads of the old plugs, and they came out with what seemed like 10 nm of torque max.

I followed the owners manual torque recommendation and used a little grease (and there was left over grease on the head threads), but became uneasy with how much twisting it took to get to 28nm or 20 ft/lbs. I stopped a bit before that number.... say 20 -25 mm with grease...

So the question from the noob here, since I apparently over toqured them to a degree, and
I'm sure the crush washers are totally flat now and they're overtorqued. What should I do?
Replace the plugs with dry threads and barely torque? Loosen and do the "1/12 turn past finger tight" as per manual? I do remember the day when replacing plug washers after cleaning the plugs was commonplace, but times have changed. LOL

Pix of old plugs and top of piston as seen through plug hole.

https://drive.google.com/open?id=0Bx...lpBbHp2QjhMc2s
https://drive.google.com/open?id=0Bx...nJzdFNIQzR3LUk

[Jason2tpa]

Engine - F300, 350 hours

Last night when replacing mine ( because I'd de-carbed/shock treated) I found that the dealer had greased the threads of the old plugs, and they came out with what seemed like 10 nm of torque max.

I followed the owners manual torque recommendation and used a little grease (and there was left over grease on the head threads), but became uneasy with how much twisting it took to get to 28nm or 20 ft/lbs. I stopped a bit before that number.... say 20 -25 mm with grease...

So the question from the noob here, since I apparently over toqured them to a degree, and
I'm sure the crush washers are totally flat now and they're overtorqued. What should I do?
Replace the plugs with dry threads and barely torque? Loosen and do the "1/12 turn past finger tight" as per manual? I do remember the day when replacing plug washers after cleaning the plugs was commonplace, but times have changed. LOL

Pix of old plugs and top of piston as seen through plug hole.

https://drive.google.com/open?id=0Bx...lpBbHp2QjhMc2s
https://drive.google.com/open?id=0Bx...nJzdFNIQzR3LUk

This thread was from almost a year ago. If you were to start a new thread with your question you will get more responses.

Personally I don't grease spark plug threads. I used to apply that same rule of thumb of tightening by hand. Then one time I needed to replace plugs I also had a torque wrench handy, so I used it to test that rule of thumb. Found it to be way under the spec lb-ft torque listed in my yamaha manual. Some people replace the crush washers, others do not like myself. I've never tested the compression pre and post crush washer application, though my engine runs the same either or.

[Captn Dave]

Put the plugs in, tighten them, and go boating.

[TownsendsFJR1300]

Engine - F300, 350 hours

Last night when replacing mine ( because I'd de-carbed/shock treated) I found that the dealer had greased the threads of the old plugs, and they came out with what seemed like 10 nm of torque max.

I followed the owners manual torque recommendation and used a little grease (and there was left over grease on the head threads), but became uneasy with how much twisting it took to get to 28nm or 20 ft/lbs. I stopped a bit before that number.... say 20 -25 mm with grease...

So the question from the noob here, since I apparently over toqured them to a degree, and
I'm sure the crush washers are totally flat now and they're overtorqued. What should I do?
Replace the plugs with dry threads and barely torque? Loosen and do the "1/12 turn past finger tight" as per manual? I do remember the day when replacing plug washers after cleaning the plugs was commonplace, but times have changed. LOL

Your links don't work..

Per my F150 shop manual, it doesn't call for any anti seize.

Greasing threads also changes the actual TORQUE VALUE your applying... It'd be higher WITH grease..

Per NGK:

https://www.ngksparkplugs.com/about-...ut-spark-plugs

[noclutch]

Thanks for the feedback guys.
I'm guessing that since my heads threads are "fouled" with grease from both the dealer mechanic and me repeating this bad habit, going forward I'm going to forget the torque wrench way of installing plugs and resort to fractions of a turn past finger tight as described elsewhere i their thread. Ie 1/2-2/3 turn and call it good regardless of torque value.

[robert graham]

Put the plugs in, tighten them, and go boating.

My 2nd on this!....My 1999 C90 Yamaha still has the original plugs...I remove them about twice a year, sand-blast them clean and white, clean threads with a wire brush, a drop of oil on threads, replace by hand and tighten nice and snug without a torque wrench....no problems so far....it ain't brain surgery!!!

[oldmako69]

Don't forget to stick them in Drano...and put a video on YouTube.

[panasonic]

Don't forget to stick them in Drano...and put a video on YouTube.

Yes don't forget the drano...lol

[TownsendsFJR1300]

LOL, love the net, and CS.....

Heck plugs are cheap and NEW ones DO make a difference...

R&R, snug down, DONE!

[99yam40]

Makes you wonder if CS got hammered by the storms,
where was he living anyway

[calif-victim]

Was the topic of a crush gasket seat plug and a taper seat plug brought up??
That could be where the confusion is coming in.

[pstephens46]

Was the topic of a crush gasket seat plug and a taper seat plug brought up??
That could be where the confusion is coming in.

What are the engineering thoughts on this taper versus "square" seat?