I had to take my cam sprocket gears off the hard way and took video of me doing it. It took me 5 minutes each to drill them out until the heads fell off.
It took me longer to strip them in the first place haha
Things you'll need:
1. 7/16 HSS Drill (DO NOT USE CARBIDE!!!!)
2. Drill motor
3. Cutting fluid, engine oil, or w/e to lubricate the drill
4. You will need a bench grinder as its almost guaranteed that you will chip the flutes of the drill entering the hex. You must also know how to sharpen a drill using a bench grinder too i suppose.
5. Rags to keep the chips out of things.
Alright well pics will come later as my camera is dead right now.
Assuming you havent done so yet your going to want to remove the timing belt. And oil pan.
Anyway aligning the timing marks and pulling the timing belt off (Theres reasoning for this so just do it). The cams on the Left head (2&4) will spin as soon as you do this, IMPORTANT NOTE!!! DONT TURN BOTH CAMS AT ONCE, ADDITIONALLY ONE CAM SHOULD TURN BACK AND FOURTH FREELY (EXHAUST IRC). ITS THE INTAKE SIDE THATS ENGAGED. now by hand rotate the cams so that no valves are open. (when you can turn it freely back and forth a little the valves are closed). Do this on both sides of the motor, although the right head is already in this state irc.
Once this is done you now know that the pistons wont hit the valves.
Looking through the bottom of the motor rotate it so that the neither 2&4 pistons are at TDC.
Its now safe to drill on the bolts.
Explanation for removing the timing belt:
1: if the drill grabs the cam will spin hopefully preventing the drill from breaking.
2: The timing belt is putting tension on the pulleys and it will cause the pulleys to shoot off as soon as the head of the bolt pops off.
Videos and pics to come tomorrow