There should be a separate screw for the vent. Some older engines had a small screw for the vent. The Flush goes right in to the water pump base and is where you would put an adapter to run the engine instead of muffs.
Carholme I had the serial number and left it in the boat. I will try to get it. Really appreciated the info. Where is a good place to get a manual then my problems can be alot easier to find out.