question for I/O guys

[cfelton]

My buddy has a 86 v20 with a 470 I/O like mine,and the O ring on the exhaust pipe to inner transom plate went bad. So we pulled the motor back about 3-4 inches to get the pipe out. We replaced the o ring ,put the motor backin and now it wont start. We checked ,it has fire, gas in the intake and good compression and the timing is dead on. Its stumped us!Both of us are pretty good mechanics but we cant figure this thing out. What the heck are we overlooking? weve checked everything. Anybody got any ideas? Forgot ta tell ya we pulled a couple of plugs and they were dry. Its like its not pulling the gas into the combustion chamber. I took off the breather and cupped my hands over the carburator throat and its really not sucking in alot. It ran perfect before we pulled the motor back. weve checked the carb base gasket and the intake gasket, they look ok.