Spark plug torque on Denso IK27 spark plugs

[Neal]

I've been trying to find the proper torque to use on the Denso IK27 spark plugs in my Lycoming 363i from CubCrafters (essentially an IO-360). I read somewhere a year ago 15 ft-lbs and am trying to find my resource but also at the last condition inspection done as owner assisted the A&P also confirmed 15 ft-lbs. But I want to verify so if anyone knows the info please let me know.

I looked up the plug at the link below and in the specs it shows the torque values so I think 15-22 is correct. Also FYI they are 14mm plugs.

Torque SpecsCast Iron: 26-30 lb. ft. Aluminum: 15-22 lb. ft.

Denso 5312 IK27 Iridium Power Spark Plug

Denso 5312 IK27 Iridium Spark Plug - Same Day Shipping. Free Returns. PayPal Accepted. Secure Online Ordering. Est. 1969.

www.densoproducts.com

I do change the plugs every year, even with lean while taxiing and LOP while flying my plugs still looked like crap. For FX-3's like mine they are cheap at $10/plug. Amazon seems to be the best place to get them and I carry two spares in the plane as well.

Amazon product ASIN B000CIY4FM

 

[Neal]

Back to this topic on spark plug torque. CubCrafters recommends 15 ft-lbs which I think is too low. In my recent saga with Lightspeed coil packs I found that Lightspeed recommends 20 ft-lbs in their installation manual. I researched the Van's forum and seems the average is 19 ft-lbs. I have been using 18 ft-lbs.

What I also stumbled upon was discussion on using anti-seize or not. I found the Denso says NO to anti-seize as it can cause the plug to be over torqued. Interesting! I also read discussions of the same on the Van's forums. Anyone here have opinions on whether or not to use anti-seize?

https://www.google.com/search?q=does+denso+ik27+require+anti+seize

 

[ve6yeq]

It would be my guess that if you use anti-seize, it has a lubrication effect and hence you need to reduce the torque value to account for the lubrication. From your Google search, someone had a "-25%" adjustment factor which then makes sense if CubCrafters is recommending 15 ft-lbs and anti-seize and Lightspeed recommends 20 ft-lbs without anti-seize.

 

[Neal]

Interesting analysis, you may be right. What I know is when I remove my plugs to inspect or replace it takes very little force to unscrew the plug at 15 ft-lbs which concerns me imaging the force on those plugs from detonation, compression, etc. I replaced my plugs yesterday and did not use anti-seize and used 19 ft-lbs. I'm sure there is plenty of lubrication on the threads on the receiver side already.