RAC1812,
I wouldn't have given much thought to torquing those bolts had you not asked the question. I looked in a manual, granted it was for a 235, but interestingly enough, it showed a torque of 25/30 ft/lbs for the two bolts nearest to the heat chamber and 15/20 ft/lbs for the remaining bolts.
I don't think this is a critical issue at all. If you tighten from the center outward, and don't over tighten and stretch the fasteners, you are going to be fine.
A flat manifold bolted to a flat head with a good gasket is far from rocket science.
The pregnant question is...what kind of beer are we talking here!
Stuart
