I'm sure you would have noticed a sticking valve when you hand swung the
prop prior to start to check for such things

"Robert M. Gary" wrote in message
oups.com...
I noticed that my Lycoming IO-360-A3B6 engine, when cold in the AM
sounds like its running on 3 cylinders for the first 5-10 seconds on
start up. After that it sounds strong and runs well. Does this sound
like "morning sickness" or just normal startup?

-Robert