Saw a guy torque a spark plug with a ratchet yesterday - is there ever a case for skipping the torque wrench on engine work?

I was at a shop in Tulsa last Thursday helping a buddy with a cylinder change and his new helper just cranked the spark plugs in with a regular ratchet. No torque wrench, just a feel for it. My buddy chewed him out but the kid argued that on older engines like the Continental O-470, you could feel when it was tight enough. I get the efficiency argument - digging out the torque wrench adds time on every plug. But I've also seen a plug strip out from overtorque on a Lycoming and the fix took half a day. Can someone actually feel the correct torque reliably on these things or is that a gamble that always catches up to you? Anyone else see this kind of shortcut on legacy engines?

2 comments

2 Comments

paige87020d ago

My first real lesson on this came back in 1997 on a Cessna 172 with a Continental engine. The mechanic I worked under back then had a hard rule: you never guess on spark plug torque, whether it's a car or an aircraft engine. The problem with the "feel" method is that a little dirt or corrosion on the threads can make it feel tight way before it's actually at the right spec. I've seen that kid's approach work fine for a while, until one plug gets just a little too much and you're pulling the whole head off to fix the threads. It always catches up with you, especially on those old engines where the aluminum is softer and more prone to stripping out.

jennifer_west19d ago

It's wild how that "good enough is fine" mentality creeps into everything, not just engines. You see it with people skipping the last step on a home project or not reading the instructions on furniture, and it always seems fine until it isn't, lol.