Loadingā¦
11
I finally stopped using anti-seize on my spark plugs and switched to torque only
For years I was the guy slathering anti-seize on every plug that went into a Lycoming cylinder, and I paid for it with two stripped threads on a customer's O-320 back in 2021. Last month I ran a little test on my own engine: pulled all eight plugs, cleaned them, and installed four with anti-seize at 18 ft-lbs and four dry at 30 ft-lbs per the Lycoming spec. After 50 hours the dry ones came out smooth and the anti-seized ones had already started backing off about a quarter turn. The torque wrench tells you the real story, and the anti-seize just fools it into thinking the plug is tighter than it is. Now I only use a drop of copper coat on the threads if the plug is going into a freshly helicoiled hole. Anyone else ditch the goop, or am I the only one late to this party?
1 comments
Log in to join the discussion
Log In1 Comment
the_tara10d ago
The torque value with anti-seize isn't really fooling the wrench into thinking it's tighter, it's the other way around. Lubricated threads need less torque for the same clamp load, so 18 ft-lbs with goop is actually giving you about the same stretch as 30 dry, maybe a bit less. Plenty of Lycoming guys have run anti-seize for decades at the low end of the range without plugs backing out, so I doubt the goop itself caused that quarter turn you saw. More likely the dry ones just carboned up and stuck a bit, which feels smooth when you break them loose. The real reason to skip it now is that Champion and Tempest both changed their guidance years ago and say install dry unless the hole is new or repaired, which lines up with what you're doing. You're not late to the party so much as the party moved and you caught up.
1