57 fleetwin woes

[tallyhoe_chap]

Hey guys I have a newly acquired 57' fleetwin 7.5. I rebuilt the carb new float gaskets etc. Change the gear oil, new plugs wires and set the gap with an ohms meter. I also converted to a single line system. My question is both before and after converting the fuel system it seems like the motor wasn't reaching the correct rpm at WOT. Yes I have tried tuning the high and low. It feels to be around 3000 rpm judging the sound of the motor. And the gps "says" I'm averaging 10mph. To those out there with more experience on this motor is that normal? It also has a leak in the new base gasket at full throttle.

 

[F_R]

Depends on the boat and load. That would be "normal" if it isn't quite enough horsepower to plane the boat. Can we assume the motor turns over freely? If it feels like it is binding, it could have a bad shock absorber in the lower unit.

 

[tallyhoe_chap]

Yes the motor turns over freely and out of gear it revs great but in gear it struggles to hit the "sweet spot" rpm. It's pushing a 200lbs + me + fuel load. It feels like it just needs 1 more mph to get on plane

 

[racerone]

Report the facts.----What are the compression numbers ?----Does spark jump a gap of 1/4" or more ,yes or no??------And are you aware of the " binding shock absorber " on these motors.

 

[F_R]

Yes the motor turns over freely and out of gear it revs great but in gear it struggles to hit the "sweet spot" rpm. It's pushing a 200lbs + me + fuel load. It feels like it just needs 1 more mph to get on plane

1 more MPH....or one more horsepower. IF your motor is up to what it is supposed to be, maybe you need a bigger motor. Up to what it is supposed to be remains to be proven.

 

[tallyhoe_chap]

I'll have to pull the gauge out again but if I recall it was in the upper 70's for both pistons. Yes it jumps a 1/4 gap and no I'm not aware of the shock binding. In gear I can spin the motor via prop with some resistance. I was referring to the "1 MPH" because I can feel the boat getting on plane for a split second then fall out. The best way I can put it is when the motor is out of gear and I rev the engine it sounds strong. When it's in gear it sounds bogged. What are some ways to test the shock absorber?

 

[racerone]

All outboards will ---" sound strong " ---in neutral.---the motor does not have to do any work !-----Shock absorber is inspected by removing the lower unit and bearing plate under the waterpump.----To remove the lower unit the power head must be removed.----All easier than it sounds and very satisfying when done properly.

 

[wrench 3]

Was running one of those on a 14' ceder strip open boat when I was a kid (many many moons ago) you never expected it to get up on plane.

 

[Chinewalker]

Before digging too deeply, confirm that it is running on two cylinders. While running, pull one plug wire off at a time with insulated pliers, and note what the motor does.

 

[silver_bay]

How long is the boat? A longer boat will be easier to plane