73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1979C20 on October 17, 2011, 05:50:18 am
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And I dont mean the electrode. I like to start my truck up and take a good look at everything to make sure its in good condition. While I was checking my plug wires to make sure they arent tou,hing my headers, my number 2 plug boot was bouncing. I looked and checked to see if the wire was clipped onto the spark plug and it was, but my spark plug was hanging onto my head by half a thread and my spark plug was bouncing around. I tightened it up and its fine now. Is there a torque rating for spark plugs? But I just wanted to tell people to make sure theyre plugs are nice and tight. I also found in my search that both freeze plugs on the drivers side have rotted through a pin hole and are dripping.
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glad you found the leaking plugs in time.
yes there is a torque rating for the plugs, i just dont have it at the moment. make sure you use anti seize on the threads and some diolectric grease on the plug end (wire side). might as well take them all out, check their color and do them all.
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I need to replace them all. But, I have other things to deal with right now, my driver side header is starting to fall off.
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22 ft lb
Most spark plugs you will use with these heads should not have anti-sieze. This is misconception by many but essentially you should not use it unless the manufacturer specifies to use it while utilizing the OEM plug.
http://www.ngksparkplugs.com/pdf/TB-0630111antisieze.pdf
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Years ago, I was driving down the highway in my ol' '74 when I heard a "Whack", and then a rhythmic racket. I'd have sworn an exhaust manifold had just busted...
But, when I pulled over and checked it out, one of my spark plugs had blown out of its hole. I threaded in a spare, popped the wire back on, and kept on truckin'. There were pucker marks in my vinyl seat, though.
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Most spark plugs you will use with these heads should not have anti-sieze. This is misconception by many but essentially you should not use it unless the manufacturer specifies to use it while utilizing the OEM plug.
http://www.ngksparkplugs.com/pdf/TB-0630111antisieze.pdf
Did NOT know this. good info!
I only been using Anti Seize in aluminum heads, not my iron heads. Good to know about the shiny coating, ive been using AS anyway on aluminum heads. wonder if its just that brand or other brands too?
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22 ft lb
Most spark plugs you will use with these heads should not have anti-sieze. This is misconception by many but essentially you should not use it unless the manufacturer specifies to use it while utilizing the OEM plug.
I find this very interesting. I have always used anti seize on spark plugs since I had one seize in a head back in the 80's. I must admit, I don't normally torque plugs and tighten by "feel". My bad. :)
Thank you for posting this information.
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It's hard for me to believe that anti sieze would change the torque values enough to overtighten a plug enough to break it off. To me it seems that the real problem would be on the other end of the wrench.
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Believe it. Just like coating cylinder head bolts, the torque values are based upon many factors including sealants and lubricants applied to the threads, tensile strength, pitch etc. I posted a lengthy thread on this a while ago. You're right though, too many people don't know how to properly tighten a fastner and can't feel when it's about to go very wrong.
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Hmmm, never knew that. I've been using never seize on plugs for 20 plus years. Only ones I have ever lost was due to the plug metal getting so rusty they blew the porcalin out.
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I was just remembering... I have had on all 3 of my chevy trucks with 350's stock head, a couple of spark plugs do just that. I don't know if they worked loose or I missed tightening them down though.
Anti sieze changes torque values quite a bit...
heres a post I mad in another thread as an example of this. the 3/4" bolts have the widest spread. around 100ft lbs.
copy and pasted~
Here's a torque value table i got from my Bowman Fasteners Torque Chart for Grade 5 fasteners
for coarse Thread (DRY - no anti-seize)
1/4" = 9 ft lbs
5/16" = 17 ft lbs
3/8" = 31 ft lbs
7/16" = 50 ft lbs
1/2" = 76 ft lbs
9/16" = 110 ft lbs
5/8" = 150 ft lbs
3/4" = 265 ft lbs
for coarse thread (WITH anti sieze compound on threads)
1/4" = 5 ft lbs
5/16" = 10 ft lbs
3/8" = 19 ft lbs
7/16" = 30 ft lbs
1/2" = 45 ft lbs
9/16" = 66 ft lbs
5/8" = 90 ft lbs
3/4" = 160 ft lbs
fine thread studs and bolts are about 4% higher values than above.
fasteners should be tightened by holding the bolt still and tightening the nut. if you have to tighten the bolt and not the nut, increase torque value by 20% (multiply by 1.20) to make up for torsional twists of the bolt shank.
I did note on the NGK page, it said to not use AS for the initial installation of the spark plugs. it says the coating comes offf when you unscrew it, so you would need AS if you reinstalled it again.
A handy dandy thing to have is a good torque value chart. I use them all the time, they have to have saved my bacon many unknown times ;)
you can usually get them at fastener stores, like fastenal or something similar, otherwise hunt the net n print it out.