17
Old timer told me to torque by feel, cost me a cylinder head
Honestly, this guy Fred who's been wrenching since the 80s swore up and down that you don't need a torque wrench for cylinder head bolts on a Lycoming. He said just go by feel and the threads will tell you when it's tight. I tried it on a 540 in a hangar in Tucson last month and ended up pulling two studs and cracking the head. Had to eat a $1,200 fix out of pocket. Anyone else ever get burned by old school advice like that?
2 comments
Log in to join the discussion
Log In2 Comments
juliag1029d ago
Stopped trusting the "feel" method after a friend with 30 years experience warped his Subaru heads doing exactly that. Thing is, torque specs on aircraft engines aren't just about tightness, they account for thread stretch and clamping force across a wide temperature range. In Tucson's dry heat, aluminum expands differently than steel studs, so a "feel" torque at 100 degrees could be way off when the engine cools down to 70 at night. I've seen it happen on Continentals too where the torque-to-yield bolts get overtightened by just guessing. Your Lycoming probably needed a specific sequence and angle, not a gut check.
10