Thanks to both of you. The engine has never been in a boat yet, it is brand new with colored plastic plugs in the orifices where the distributor, thermostat, and carb mounts. The intake manifold is a cast iron manifold for a two-barrel carb. The distributor, thermostat and housing and carb will transfer from my present engine which the paperwork says is 300 hp. My present engine spun a bearing and is coming out of my boat tomorrow. I just do not want to under-power my 26 ft fiberform Cabin Cruiser that weighs 5000 lb with fuel and water but no passengers. I guess that if it is 250-260 hp that I should close to the performance of the 300 hp engine. The boat came up on plane readily and topped out at 34 mph. Again thank much. Tom