I have dark almost black arm air all over my arm and it's truly awful I also have a LOT of it so it's totally noticeable I hate the idea of waxing what would truly happen if I shaved?
Im not really a mechanic but i believe it might burn valves. If it is a 22re toyota pickup motor they are supposed to tap overtightening them may lead to a burnt valve.
There are many arm muscles. The triceps (on the back of your upper-arm) contract when you straighten your arm, and the biceps (the front of the upper-arm) relaxes.