Use a straight edge such as a long carpenter's level to check for misalignment between the two manifolds. Once you separate the two, it can be hard to get them back into proper alignment on re-installation. Leaving the four intake/exhaust bolts slightly loose while getting the manifolds snugged up to the head helps, then tighten them last.
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!