75hp evinrude wont go with engine cover on

[bdmack]

I have a 62 75hp evinrude starflight 4. i rebuilt the carb, replaced the rings, honed the cylinders, and everything. The thing smokes a lot, even under the alien head looking engine cover housing thing. Should it? I cannot get it to run well unless the cover to the carbs is hanging open. It runs even better without the cover on at all... Running rich, that seems obvious, but this seems silly. I even removed the air filter things that are on the bottom of the motor cover. This is happening at all speeds. I have checked the float level four times, and tested the float for buoyancy. Any help? Also, no matter what the book states, I cannot get the carbs to sync to the distributer as described in the book. I have the flywheel to distributer lined up per book instruction. The carb linkages cannot be lined up as the book has it drawn out, and still run.
I am pushing a little finned 14' 1957 reinell runabout with the motor, and have it running an easy 25 to 35 mph fully loaded. Any ideas??? Near ready to use the old sledgehammer tuning device. I appreciate any help I can get.
Also- What prop would seem proper for this little boat. Currently running a 10 x11 something.....

 

[Solittle]

Re: 75hp evinrude wont go with engine cover on

Your description fits an exhaust leak under the cowl depriving the air mix to the carb of oxygen. Take the cowl off and the fresh air clears enough of the exhaust gas.

Oh and WELCOME!!

 

[F_R]

Re: 75hp evinrude wont go with engine cover on

solittle nailed it, but he didn't say where the leak is. I'll betcha you put a new water pump in it, didn't you? You left out the foam seal that goes on top of the pump housing cover. That problem will drive a guy nutso if he doesn't know that will happen. The seal is part number 305762, at your dealer. Glue it to the pump cover to make installation easier.

 

[bdmack]

Re: 75hp evinrude wont go with engine cover on

I think you nailed it. I saw one of those foam gaskets when rebuilding and did not put one back on,(stupid huh). That will also explain (I hope) the black ooze that dribbles out onto my shop floor after taking the boat out. I'm also curious about fuel consumption. I easily burn 4 gallons in an hour running it at near full speed for 1/2 of that time, and idle to half throttle for the rest. Is this normal or excessive? How about a prop recommendation, anyone?

 

[Evinrude Boater]

Re: 75hp evinrude wont go with engine cover on

That black ooze is unburned fuel, carbon and exhaust all mixed together. You won't get rid of it. You can minimize it by tuning your engine for optimal performance and not idling prior to coming in. Fuel consumption, who cared about fuel economy in the 60's when gas was 30 cents a gallon. Again, tuning your engine and throttling back a bit from wide open throttle (WOT) and you'll save a bit. It was a feature call "Cruise-throttle". If you take the hood off and look at your carb linkage as you push the throttle all the way then start pulling it back and watch for movement in the butterly plates. You'll see how much you can pull back before the butterflies start to close. As you pull back this changes the timing advance...I think. This is a thirsty engine....remember 30 cents a gallon, who cares? I think the rule of thumb was hp/10= gal/hr @ WOT. My engine came with a 10x9 1/4 prop. I don't know if that's a good speed prop or economy prop but we ski and wakeboard behind it with no problem.

 

[F_R]

Re: 75hp evinrude wont go with engine cover on

Those engines burned at least 6 gallons per hour at full throttle. Trouble is they also used a lot at idle, where they dumped as much overboard as they burned. That's the black ooze you see. Normal.