YOu have to be careful with the head bolts. The recess the wrench fits into will be filled with oil and perhaps dirt, so you have to be sure it is cleaned out well so that your wrench will seat fully. If it is not seated or you get it angled instead of perfectly straight you will have the problem that you saw.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.