stuck valve cover on 90?

[buffalobill]

i have a stuck valve cover on my atc 90, the head is stripped after multiple tries with first a 23mm wrench, and then vice grips. i have soaked it in wd40, and banged on it pretty good with a hammer. my next step is to put it in a vice and grip it around the circumference with a pipe wrench. if this doesn't work, any other idea's? my last ditch plan was to just start drilling holes around the inside area of the threads so i could take a hacksaw and cut to the edge of the threads, and possibly crack whats left with a chisel.

anyone else have this problem?

[Dirtcrasher]

You mean the valve adjustment caps? The outside is very thin (where the o-ring is underneath) I've used a punch and cracked that portion away, all the way around, then you can get out the caps.

A pipe wrench on the OD may crack it too, or break it loose.

For SOME reason, people put them on super tight.

Another method I use is to sharpen a chisel, angle it and place it on the top of the flats. Tap it in the loosening direction and lots of things break free this way.