That is the river cruiser hull will cutter bow....slips thru water better. The earlier models with the 318 Chizzlers and Dana drive would actually plane and run high 20's MPH...same hull
Being a V-drive it most likely has 15x12 props ,one RH and one LH. If boating on a lake GPH will only change with load. If on rivers you will use more fuel going upstream vs down.
Here...used a bunch of em...
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That sludge is from unburnt fuel in exhaust not lower unit oil. As Racer stated you need to replace water pump assy and seals on driveshaft as they could have heat damage
All the newer motors work great in saltwater...its what maintenance that occurs when its removed. They (motors) all require extra attention from salt use so be diligent on flushing cooling system ,greasing fittings and use salt inhibitors in spray or wipe on applicators'
To do it properly the crank needs to come out of motor but if your going to go that far just replace it. Other option is to get another crank nut and split it in half and torque to spec
Adjust the carbs in a barrel or lake to apply backpressure. Start at bottom carb and work way to top one. Make sure motor will run without carbs being cracked open with roller.
