friggin exhaust manifold studs!

[Ameer Antar]

I  don't know what's going on, but something's messed up. I tried tightening the manifold nuts today but what a FPITA! I couldn't get to the lower nuts on cyl 3 & 4, and even 5 gave me trouble at the end. It seems part of the problem is also there's not enough room for the socket to fit on between the nut and manifold. Another major problem I had was when I tried to torque the nuts down. The Bentley says 26 ft-lbs which is a lot, but anyway on several that i could reach, the nuts keep spinning (and it looks like the stud too). What's going on???? 

Just so you know, the head was rebuilt by a local shop but I replaced all the studs w/ new ones. The threads in the head all looked like spiral-locks, but I figured that must be the design since it's an aluminum head, and all of em had it. Hope someone can offer some help... TIA.

-Ameer