Seems to me that running rich is running rich, not timing. I guess maybe poor timing wouldn't combust the gas/air charge properly, but that doesn't seem likely . . .
When we were reassembling our freshly-rebuilt 216, we also freshly rebuilt our Carter W-1. Along with some other kinks, we had a rich situation, with quickly fouling plugs, and dribbling gas after shut-off.
Turns out the float valve seat had worked loose (we probably hadn't tightened it properly), so gas would keep flowing, even with the float up. Easy fix.
Possible leaking float, as well. I know disassembling the carb can be a pain in the A$$, but take it slow, don't lose any parts, and check the float. It's not too bad to just pull the top off to get to the float. Float should basically sit level when the assembly is held level. There's a proper measurement, can't remember it right now. Double check the float valve and pin, and seat. If they're all good, and float is reasonably close, you should not get a drastically rich condition.
Report back what you find. Hope this helps!
-Michael
