Spark Plug Torque ?
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Junior User
Joined: Dec 2006
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From: Prairie View, Texas
Spark Plug Torque ?
I have seen recomendations all over the specified range ( 84 - 168 in lb) for plug torque. I just retorqued mine @ 132 in lb figuring better on the low side than to much. Any comments or suggestions ?
'99 F250 SC V10 83,000
'99 F250 SC V10 83,000
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Too low in my opinion
The range I shoot for is 160 to 165 inch pounds on a calibrated "click" type torque wrench that read 60 to 320 inch pounds so 160+/- is near mid range
The moving pointer "T" bar type torque wrenches are no good for this operation unless you are a pro and have a well calibrated eye.
Too loose is just as bad as too tight for this reason: Each plug will go through a lot of full hot to full cold cycles and the steel plugs and aluminum heads expand and contract at different rates, usually a fastener that is too loose will loosen up further. At 132 inch pounds you are at 11 of the 16 foot pounds.. This is roughly 65% of max torque.. you need to be around 85~90% of max to ensure no over torque and solid contact of the mating shoulder
The range I shoot for is 160 to 165 inch pounds on a calibrated "click" type torque wrench that read 60 to 320 inch pounds so 160+/- is near mid range
The moving pointer "T" bar type torque wrenches are no good for this operation unless you are a pro and have a well calibrated eye.
Too loose is just as bad as too tight for this reason: Each plug will go through a lot of full hot to full cold cycles and the steel plugs and aluminum heads expand and contract at different rates, usually a fastener that is too loose will loosen up further. At 132 inch pounds you are at 11 of the 16 foot pounds.. This is roughly 65% of max torque.. you need to be around 85~90% of max to ensure no over torque and solid contact of the mating shoulder
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Junior User
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From: Prairie View, Texas
Ok Sarge, on page two of this forum "tmehrkem" posted his plug change sequence with photos and he said torque to 132in lb ( which i just finished the last one an hour ago) I used an inche pound clicker torque wrench. Now should I go ahead and retorque to 160 in/lb ? I've heard that the '99 has fewer threads so will "tighter" still be better ? Your reasoning makes sense to me.
- Blow out the dirt arround the COP.
- Remove the 7mm screw holding the COP.
- Pull up and remove the COP.
- Press the tab and unplug the COP.
- Blow out the spark plug hole.
- Inspect the plug using a mirror.
- Blow out again if necessary.
- Loosen the plug using the spark plug socket and rachet.
- Blow out again.
- Inspect again.
- Unscrew and remove plug
- Lightly coat the plug threads with anti-seize.
- Put the new plug in the spark plug socket.
- Carefully start the plug. Make sure it is not cross threaded.
- Torque the plug to 132 in lb.
- Pull the spark plug boot off the COP.
- Put ignition grease on the inner surface of both ends of the new boot and iinstall the boot on the COP.
- Seat the boot and COP on top of the new plug.
- Put anti-seize on the COP screw.
- Secure the COP with the screw.
- Repeat 10 times.
Last edited by jutahh1; Jan 21, 2007 at 09:35 AM.
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If you followed that sequence just as it is written, you are in good shape.. now tell the truth did you use the anti sieze? If so did you do what I always recommend and paint it INTO the threads with a small acid brush and wipe off all the excess?
If you suspect for any reason a previous high torque or over torque then stick with what you have.... I still like a tad higher torque byt that is me because I do not want to keep screwing with checking them frequently...as you know getting the COPs off is a royal PITA
In 10,000 miles or one year which ever comes frist remove each COP inspect the plug boots and break each plug off torque and re torque to 132~140 and keep trucking... if you choose to go to a higher torque you can let them stand in the hole for 30,000 or 24 months
no matter what torque.... do not let these plugs go unchecked for more then 50,000 or three years
If you suspect for any reason a previous high torque or over torque then stick with what you have.... I still like a tad higher torque byt that is me because I do not want to keep screwing with checking them frequently...as you know getting the COPs off is a royal PITA
In 10,000 miles or one year which ever comes frist remove each COP inspect the plug boots and break each plug off torque and re torque to 132~140 and keep trucking... if you choose to go to a higher torque you can let them stand in the hole for 30,000 or 24 months
no matter what torque.... do not let these plugs go unchecked for more then 50,000 or three years
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Junior User
Joined: Dec 2006
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From: Prairie View, Texas
Just finished the plug job..... Autolite APP103 gap .54 torqued to your reccomendation of 165 in/lb antisiez and dilectric grease on boots. Now I have a broken exhaust manifold stud to tackle next ! GO ARMY!
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