The Harmonic Slipped?
Not possible, it has a keyway to lock onto.
More likely that you slipped a tooth or two on the timing Chain.
IF i am correct in what you have done (highly likely have done it myself
), then there are two ways to fix it.
Properly or patch it. (patching it will work if you haven't slipped too far)
Properly involves redoing the head, dropping the sump a little, pulling the harmonic, and timing cover.
Pull #1 plug, and set TDC from the hamonic. You should confirm TDC with a piece of welding wire down#1 plug hole.
Pull the rocker cover and see if the exhaust and inlet rockers are free (not under pressure). If they are not free, then you need to remove the timing sprocket and rotate the cam until they are.
This method IS NOT 100% reliable, as you can still be a tooth out.
When doing this, and any work where you unbolt the Cam sprocket it is IMPORTANT to keep tension on the chain at ALL times, as it is so easy to slip a tooth on the crank end.
Another thought (excuse me..had a few jars
) Have you run through the timing procedure????
Did you have to move the Dizzy much? In theory you should not have had to touch it, unless it was already out. If you had to move it a fair bit, it is a good indication that you slipped a tooth or some on the timing chain.
Timing WILL affect temperature.
If you didn't re-time the engine, find the procedure and check it....you may be surprised.
Hope this helps