hello everyone i own a 63 apache with twin LYCOMING O-540-B1A5. & rebuilding both of them. & well let just say my dauther soon to be pilot ran both up & the service manual met the left side propeller. you do the rest, & now I'm at the point when I'm ready to drop both Engine's back in, but i don't know what the plug gap is, due to the manual meting the propeller. if anyone knows of where i can go to look it up, i would appreciate it. or know what the gap is i would appreciate it as well.