Originally posted by Streets
Correct way to install a spark plug: Screw in the spark plug finger tight until the gasket meets the cylinder head. Then seat the plug/gasket with a torque wrench as specified in the chart below.Chart is in (Ft.Lbs.)

Spark PlugType.......Thread Diameter........CI Head......Alum. Head

Flat seat type............18 ø mm..................25.3~32.5..25.3~32.5
(w/gasket)...............14 ø mm..................18.0~25.3..18.0~21.6
...................................12 ø mm..................10.8~18.0..10.8~14.5
...................................10 ø mm....................7.2~10.8........7.2~8.7
.....................................8 ø mm............................................5.8~7.2
Conical seat type........18 ø mm....................14.5~21.6...14.5~21.6
(w/o gasket)
Conical seat type.........14 ø mm...................10.8~18.0.....7.2~14.5
(w/o gasket)
I wuz just reading the installation instructions in my spare NGK BR8ES box. And how do you read that? I can't seem to figure it out. My method's better than my tech teacher's, his is " Tighten it till it feels right ". Oh, all those mm thread things are written in Japanese so, don't think he'll be able to follow that chart. Is that the chart used for car engines? I never use charts, I just use the 1/4 turn thing and, I'v never had a problem although a chart is the Official proper way to torque the spark plugs.