Ah marine engine's eather idle or wot prop pitch is what determine the max rpm. They get the most abuse compaired to automotive engine's I bet that thing screamed along @ 5000 rpm or so when prop was matched correct. said Such a cool ad, I had no idea that some boats had a 440+6 in them. Not sure why the carbs would be different than autos. Maybe they were set up a little differently because boats typically run at a lower rpm. Click to expand...