Once all the slack is taken up so the manifolds are snugged up against the head, turn each bolt/nut one flat (1/6 turn) tighter. That's about as accurate as using a torque wrench. I use the same basic procedure when tightening wheel nuts if a torque wrench isn't available.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!