On my SDL I found two of the head bolts with the head filled with hardened steel, I'm pretty sure it was broken triple-square bit tips.

Anyway, the rest gave me no trouble with an S-K bit I bought decades ago for quattro CV/Axle nuts.

Back to the ones with bits inside: Drills wouldn't do it, burned up several special hardened bits, couldn't even center-punch them for drilling. Back to Autozone for the IRWIN brand internal-helix type bolt extractor set, about $20 in a nice blue plastic box. For the one external to the cam cover, the extractor worked great, no problems. For the one that was in the cam-tower, I had to grind the external hex off of the extractor for it to fit in the hole around the bolt head, but tapped it down lightly using the socket extension and a brass mallet, and it easily gripped and removed the bolt. I was tempted to use the extractor for all of the bolts instead of the triple-square bit, but no broken bit so it worked okay.

Wish your car were closer, we could do a 2 for 1 here, I am just starting the head R&R on my 603 before installing it in the '95.

__________________

Gone to the dark side

- Jeff