<VV> Frustrating weekend update

[Chris]

My first post was long, so I'm just going to start where I left off.  Thanks
to everyone who has responded so far.

 

First, for those who asked, I have a powerglide.

 

Second, I checked the oil.  It is at the full level, not overfull, and no
smell of gasoline.  I took out all six spark plugs.  Numbers 1, 3, 5, and 6
had wet tips.  After taking out each spark plug, I tried to crank the motor
using the starter.  No luck. until all six plugs were out.  Once there is no
compression possible at all, the starter will spin the engine.  I let it sit
for a few hours, figuring that any gas in the cylinders would evaporate out
(or maybe was pumped out while I was spinning the engine).  By the way, when
I was spinning the engine, NO gas came out of the spark plug holes.

 

After a few hours, I put the plugs back in and tried to crank it again.
With the plugs in (even with one plug in), the starter will not spin the
engine.  Took the plugs out again, and it spins just nicely.  There is no
clatter or noise in the engine when it is spinning, so I don't think there
is an issue in there.  

 

Several suggested that my ground wire or my 12 volt supply to the starter
might be at fault, so I eliminated that possibility by putting the positive
and negative from my 200 amp charger/starter directly to the starter.  The
starter pulled a lot of juice out of that charger, but still wouldn't crank
the engine.  

 

Is it possible for a starter to function fine when it is not under load and
to malfunction when it is under load?  On the tester at the local parts
store, it passed the tests, and it seems to hum right along, but it sure
isn't turning this engine when compression is part of the equation.  

 

I considered the possibility that the harmonic balancer might have slipped,
causing to valves to be in a closed position when they should be open, but I
inspected it, and it looks nearly new.

 

What should I check next?