Hi Matthew,

The small tube of yellow stuff is for the head capnuts.

First, you really should get a tap and die to clean out the capnuts and
clean off the head studs.  When you put the capnuts on ... ONLY put the
yellow stuff on where the nut mates with the head.  Don't get any inside
or on the threads or you could have a hydraulic lock and the torque
wrench will give you a very false reading.

The larger tube of black stuff is for the big rubber gaskets between the
heads and the case.  Apply it to both sides of the big rubber gasket.

My gut feeling ... and according to the directions on tubes of "Similar"
sealants ... I'd say you should be somewhere that will achieve 40� or
more while you're doing the work.

Mike