C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

torque spark plugs

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Old Mar 6, 2010 | 11:29 AM
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Default torque spark plugs

How many pounds of torque for my 86 350ci.
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Old Mar 6, 2010 | 11:41 AM
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I would find it difficult to torque a spark plug with clearance issues between the wrench and the body. Just get them tight.

Do you have cast iron or aluminum heads? Not sure....test with a magnet. The magnet will stick to cast iron, not aluminum.

If you have aluminum heads....BE SURE to use anti-seize on the plug threads.
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Old Mar 6, 2010 | 01:03 PM
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Originally Posted by John A. Marker
I would find it difficult to torque a spark plug with clearance issues between the wrench and the body. Just get them tight.

Do you have cast iron or aluminum heads? Not sure....test with a magnet. The magnet will stick to cast iron, not aluminum.

If you have aluminum heads....BE SURE to use anti-seize on the plug threads.
I was able to get a torque wrench on all the plugs on my 89. I don't recall if I used a swivel though.
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Old Mar 6, 2010 | 01:05 PM
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Originally Posted by lexman52
How many pounds of torque for my 86 350ci.
According to my Haynes:

Cast-iron heads = 22 ft/lbs

Aluminum heads = 12 ft/lbs
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Old Mar 6, 2010 | 01:29 PM
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As far as I know (Helms Manuals) 22 ft/lbs all heads - the only way to accomplish this is with the Heads removed. Install the plugs with the correct torque before you install the heads.
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Old Mar 6, 2010 | 01:52 PM
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Originally Posted by SunCr
As far as I know (Helms Manuals) 22 ft/lbs all heads - the only way to accomplish this is with the Heads removed. Install the plugs with the correct torque before you install the heads.
I was able to torque all the plugs on my 89 with the engine in place. I'm sure I probably used a swivel on some of the plugs though. I do believe the torque values are different for cast-iron and aluminum heads.
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Old Mar 6, 2010 | 01:55 PM
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Also torque values vary when using swivels. I just snug down the plugs and have never had a problem with one coming loose.
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Old Mar 6, 2010 | 01:59 PM
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Originally Posted by STL94LT1
Also torque values vary when using swivels. I just snug down the plugs and have never had a problem with one coming loose.
Yeah, I think you have to add 2 ft/lbs or take away 2 ft/lbs. I forget.
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Old Mar 6, 2010 | 02:55 PM
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Originally Posted by John A. Marker
Just get them tight.
If you have aluminum heads....BE SURE to use anti-seize on the plug threads.



German torque for me too......goodentight

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Old Mar 6, 2010 | 04:07 PM
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Thanks guys, all set at 22lbs.
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Old Mar 6, 2010 | 05:04 PM
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Originally Posted by lexman52
Thanks guys, all set at 22lbs.
So, I'm guessing you have cast-iron heads?
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Old Mar 6, 2010 | 05:21 PM
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Originally Posted by STL94LT1
Also torque values vary when using swivels. I just snug down the plugs and have never had a problem with one coming loose.

You do not want to tighten them to tight you might want to get them out another day. I do the same as STL94LT1 and have never had an issue at all.
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Old Mar 6, 2010 | 05:27 PM
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I torqued the plugs on my 86 aluminum head L98 to factory specs and did not have any problems doing it, although the passenger side front plug required a universal adapter to get the T.W on it. All worked out just fine for me.
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Old Mar 6, 2010 | 05:39 PM
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Originally Posted by pmihaltian
I torqued the plugs on my 86 aluminum head L98 to factory specs and did not have any problems doing it, although the passenger side front plug required a universal adapter to get the T.W on it. All worked out just fine for me.
What ft/lbs is that? Just wondering if they are the same as the Haynes manual.
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Old Mar 6, 2010 | 09:17 PM
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Originally Posted by joshwilson3
What ft/lbs is that? Just wondering if they are the same as the Haynes manual.
Ft/lbs is incorrect; should be ft lbs. Also, torques are normally specified for clean, dry threads. If you are using anti-seize or any other lubricant you need to back off on the torque value.

Steve
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Old Mar 6, 2010 | 09:20 PM
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Originally Posted by azrocketman
Ft/lbs is incorrect; should be ft lbs.
Steve
Sounds the same to me. How about lb/ft?
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Old Mar 6, 2010 | 10:03 PM
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Originally Posted by azrocketman
Ft/lbs is incorrect; should be ft lbs. Also, torques are normally specified for clean, dry threads. If you are using anti-seize or any other lubricant you need to back off on the torque value.

Steve
Are we going to the moon in this or what ?
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Old Mar 6, 2010 | 10:39 PM
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With old threads Id be worried about a failure. Get them good and snug, maybe add a touch of oomph thats it. Yeah I know, neanderthal.
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Old Mar 7, 2010 | 08:06 AM
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Good God, why make this harder then it has to be, just put them in and snug them up. Ive never used a torque wrench on a plug in 50 years and never had any problems....WW

Last edited by WW7; Mar 7, 2010 at 08:08 AM.
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Old Mar 7, 2010 | 09:48 AM
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Originally Posted by WW7
Good God, why make this harder then it has to be, just put them in and snug them up. Ive never used a torque wrench on a plug in 50 years and never had any problems....WW
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