Any exhaust system experts have any advice to offer?  I just installed a
new 2.1 engine in a 90 and ( with engine out) bolted on new exhaust
header pipes and the heavy elbow flange that joins them together on the
LH back corner. It was a bit of a bear to get em all to mate up
properly, but with a lot of loosening and tightening and coaxing I
thought I got em all snug ( poor fitting aftermarket parts I'm
thinking). Well after start up it looks like I have an exhaust leak at
one of the connections to the large elbow flange.  Damm - I'm thinking
these were hard enough to mate with engine out, now I have to do it on
my back  and looking up !

So are there any tricks here ? Use a gasket sealer along with the
regular flange gasket? Are regular nuts better than copper as it might
be easier to tighten them down more ? I used copper thinking they were
superior. Maybe I just need to use a bigger ratchet and tighten the crap
out of the bolts, at the risk of breaking a bolt though. Maybe it's not
uncommon to have to loosen/re-tighten them after a few heat/cool cycles ?

Any sympathy and or suggestions appreciated.   -john