stripped derby cover threads
 

What to do.
I was changing the derby cover and was torquing to spec when the 5th screw would not click. Any how over tightened and when I back the screw out it came out with the aluminum threads from the outer primary cover.
What should I do?
Helicoil? Bigger thread size and bigger screw? Retap with 1/4 28 to move up in size from 1/4 20? Help?!

you have enough meat there to drill and heli coil however your going to have to pull the cover as you will go though the back of the bolt thread seciont and dont want those shavings in the primary... teflon tape the bolt when you install it and no leaky leaky

drill all the way thru
 

I read somewhere that you won't want to drill all the way thru. Are you sure it's acceptable to drill all the way thru?

i did on mine years ago, never had an issue, i first tried to drill it out without going all the way though and used a flat head tap to retap it, did not get the bite i hoped for so i drilled it, teflon on the bolts and never had an issue. later i welded up the intdent on the primary and replaced the primary to do it but it worked great for years

I stripped one hole and was able to helicoil without going all the way through, but it was a PITA, would me much easier to just drill through

How did you make it work with such a shallow hole?