I just put a new long block in my boat. I rebuilt the carb, replaced
the distributor, points, condenser, thermostat, coil, new spark plugs,
and it had a new starter on it when I got it.

I finally got it to run hooked up to the muffs so I took to the lake
today to see how it does in the water. It idles at 800 rpm like the
book says. Oil pressure is great. Temp stays at 165. It runs solid and
smooth up to about 2200 rpm. It then sputters and acts like it may be
missing or choking out and will slowly get to around 2400 rpm. The
speed is 15 mph.

Any ideas on what it could be? Will the timing advance keep the engine
from going into the higher rpm range? Or is it more likely I screwed
something up on the carb when I rebuilt it?

About the only thing I haven't changed is the timing advance parts.
It's a centrifigal advance. How would I know if it's bad?

Any ideas? I have worked my tail off for the last month getting this
engine in and running and it's so close I can taste it. If I can just
get this last thing fixed so it will go to WOT then I will be done.