Ford Excursion 2003 140K original spark plugs. I used two torque wrenches one was a beam type the other a clicker type. Both torque wrenches were Sturtevant high quality. Plugs 2, 3, and 5 plugs had around 75 inch/pounds of torque finger tight.

I torqued plugs dry no never seez applied to 150 inch pounds slight above 12 foot pounds maximum is 14 foot pounds. The other plugs broke about 175 inch/pounds. The rubber boot was badly cracked on cylinder 2.

I plan on replacing the other boots from the set when I retorque the plugs next year to 150 inch/pounds. The gap on the plugs were at .068-.070. The new plugs gaped at .052 installed motorcraft had the same P/N as the original plugs.

I think that the steel and aluminum having different heat coefficients the heat and cooling loosens the plugs. One of the plugs had crud built up on the seat of the plug. I was fortunate, knowing what I do now I would have done this job much sooner

 

Don't be surprised if you replace the plugs around 60-70,000 mi.with better performance. Don't agree with the 100,000 mi change interval. More hype than fact. Sure the engine will run , but the decline in performance is so gradual most people don't notice it.