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Discussion Starter #1
Hi All,

I've searched and searched but haven't found concrete info.

2012 Impala LTZ - 3.6L.

Changing the plugs this weekend with OEM: AC Delco: 41-109.

I'll be able to torque the front plugs, but not the rear due to the intake.


1st question: Gap
- Manual says .043". I'm reading some people on the forums saying .040". Thoughts?

2nd question: Torque
Online I am reading Torque spec: 15 ft/lbs. Correct?
I can torque the front 3, but not the rear due to the intake.
Is everyone just doing the 1/8th turn?

Thanks!
 

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Discussion Starter #4
@jtrosky - Thanks for the reply! I've actually been through that thread and all over youtube haha.

I was planning on leaving the intake on - more curious what people have been doing to torque down the rear spark plugs?
I figure I could do the front three, gauge the angle on those, and try my best to do the same on the rear? Or has someone successfully gotten a torque wrench back there??

Second question - The manual says .043" gap - but even in that thread you shared people are saying .040. which is it?
 

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Not sure about the gap - I'll try and check my service manual and see what that says.

To torque the rear spark plugs, I'm assuming you can do it with a torque wrench using some extensions (maybe the kind that "pivot")? I haven't done it yet myself.. I'm sure someone that has done them will chime in shortly though.
 

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Maybe I'm dumb, but I always just do spark plugs by feel. I suppose you could do the front ones with a torque wrench, and then put the wrench you are gonna use for the back ones on the fronts and feel how much effort it takes to turn it a fraction more. Should get you in the ball park.
 

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@jtrosky - Thanks for the reply! I've actually been through that thread and all over youtube haha.

I was planning on leaving the intake on - more curious what people have been doing to torque down the rear spark plugs?
I figure I could do the front three, gauge the angle on those, and try my best to do the same on the rear? Or has someone successfully gotten a torque wrench back there??

Second question - The manual says .043" gap - but even in that thread you shared people are saying .040. which is it?


GM has issued TSB’s stating NOT to change the gap on the ACDelco iridium spark plugs, as changing the gap can damage the iridium coating on the tip (it is not solid iridium) and thus damage the plug’s longevity.
 

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Just did mine a couple months back. It’s tight back there, but you do not need to remove intake. Tightened mine by feel also.
How many miles on your car and how did the plugs look? There is a rebate on AC plugs till the end of this month so I am going to grab some for both the Impala and the Yukon.
 

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Read this entire thread - you can change the rear plugs without removing the intake or anything else. The one member even made a video showing how easy it is near the end of the thread:

http://www.impalaforums.com/chevy-impala-8th-gen-discussion/718378-lfx-spark-plugs-who-s-done-it-3.html
Yep, this was the thread that got me started here. Came in to thank that user.

I used autolite plugs for mine, gap was called for being .040 and went to tight to feel rather than attempting to use torque wrench. Dialectric for boot, but did not use any antiseize on the threads.
 

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How many miles on your car and how did the plugs look? There is a rebate on AC plugs till the end of this month so I am going to grab some for both the Impala and the Yukon.
I was about at 90k. Plugs didn’t look that bad, not too “burnt”. Glad I went ahead and did them though. Also, I always use just a bit of anti-seize on plugs.
 

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For those, like myself, who like a little more detail, here's an 8-minute in-depth video ...

Cheers!

T-

 

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^+1 on the great video! Only things I'd add: Dab of never-seize on the plug threads, dielectric grease applied inside the boots with a small screwdriver or cotton swab and instead of dropping the new gapped plugs down in the plug hole, I insert them into a scrap piece of 3/8" hose and gently position and start them by hand with the hose attached. When plug is started, hose will stop or slip. Pull hose off and tighten with ratchet, extension and plug socket.
 

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a short piece of 3/8" hose and insert the plug cap into the hose and then hand thread those plugs into the aluminum heads. Engine must be cold.
 
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