That day I realized I was torquing spark plugs wrong for 5 years

I was working on a Lycoming engine last Tuesday at my shop in Nashville (it was an old Cherokee 140) and a senior guy walked by while I was tightening a spark plug. He just stopped and said 'you know that washer is supposed to crush flat, right?' I looked at the plug I had just put in and the washer was barely deformed. I had been tightening them just barely past finger tight for years (I thought I was being careful). How much extra torque do you guys usually give them after the washer contacts the cylinder head?

2 comments

2 Comments

the_stella1mo ago

Read somewhere that most plugs need about 1/4 turn after the washer hits.

james_campbell121mo ago

That's pretty much what I've always done too.

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