Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 times

I have the motor running now but cannot get it dialed in all the way. I can get it to idle great and it will get to top speed eventually. there is a good deal of sputtering as it tries to reach top speed. Once I get to top speed I can back of to mid speed and then it re-accelerates very nicely back to top speed. Now I have broke the carb down 3 times and cleaned as best I know how. Carb cleaner, then blown out with air compressor etc.

There is also what appears to be a lot of fuel behind the motor as I idle and then when I hook the boat to the trailer I always leave a good deal of fuel right at the ramp ( the ramp is steep though.)

I have attached and image of the fuel in the water, there is a strong gas smell and it does not accelerate smoothly from a stop

I cannot figure this thing out, I have made adjustments to the carb while on the water and if I lean things up it dies and wont idle or start and if I rich it dies.

When I first accelerate is hesitates and then speeds up like it grabs some fuel and or burns off enough for it to run right, then there is another hesitation and the same thing repeats until it finally get to top speed.

Any thoughts

Re: Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 t

year of motor would be nice just a wild guess your needle is stuck open when you reach top speed eventually it's burning off excessive fuel then it runs good just by all the problems you said it sounds like your needle is stuck open

Re: Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 t

Did you set the float levels when you rebuilt the carbs. Definitely running rich will cause your symptoms.

Re: Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 t

fmalott said:

year of motor would be nice just a wild guess your needle is stuck open when you reach top speed eventually it's burning off excessive fuel then it runs good just by all the problems you said it sounds like your needle is stuck open

Click to expand...

Sorry here is the motor info, it is a 1963

It is a Johnson Super Sea Horse, Electric, I think 75HP
V4S 15R
2385713

Re: Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 t

rickdb1boat said:

Did you set the float levels when you rebuilt the carbs. Definitely running rich will cause your symptoms.

Click to expand...

When you say set the float levels, do you mean the float is suppose to be parallel with the surface of the top of the carb, I just followed the specs in the manual. Is that what you mean?

This is a 1963

It is a Johnson Super Sea Horse, Electric, I think 75HP
V4S 15R
2385713

Re: Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 t

fmalott said:

year of motor would be nice just a wild guess your needle is stuck open when you reach top speed eventually it's burning off excessive fuel then it runs good just by all the problems you said it sounds like your needle is stuck open

Click to expand...

When you say needle, do you mean the small peice that goes under the float?

Re: Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 t

I'm leaning toward a syncronization issue. You say that the engine stumbles a bit while bringing it up to WOT but that it smooths out if you bring the throttle back down a bit then increase to WOT again. The linkages will advance the distributor and throttle plates at the same time. When you move the throttle lever to increase rpm, the distributor will be fully advanced before the throttle plates open completely. If you continue to move the throttle level, the throttle plates then open completely even though the distributor cannot advance any further. It seems that (perhaps) that last bit of throttle adjustment that occurs after the distributor is fully advanced but before the throttle plates are fully opened is a bit suspect. Did you syncronize exactly according to the factory service manual?

BTW, this applies to distributor ignition systems. If you have the magneto, then perhaps things are different, but I don't believe so. I believe that the principal of spark timing (retarding or advancing) is the same for both systems. Can somebody verify this?

Also, note that cruising speed is attained by fully advancing the throttle until on plane and then backing down the throttle a bit. This allows the throttle plates to close just a bit while keeping the spark timing fully advanced. Joe Reeves taught me that one.

Re: Still can;t get this 75 HP Johnson dialed in, Have rebuilt carb and recleaned 3 t

yorab said:

I'm leaning toward a syncronization issue. You say that the engine stumbles a bit while bringing it up to WOT but that it smooths out if you bring the throttle back down a bit then increase to WOT again. The linkages will advance the distributor and throttle plates at the same time. When you move the throttle lever to increase rpm, the distributor will be fully advanced before the throttle plates open completely. If you continue to move the throttle level, the throttle plates then open completely even though the distributor cannot advance any further. It seems that (perhaps) that last bit of throttle adjustment that occurs after the distributor is fully advanced but before the throttle plates are fully opened is a bit suspect. Did you syncronize exactly according to the factory service manual?

BTW, this applies to distributor ignition systems. If you have the magneto, then perhaps things are different, but I don't believe so. I believe that the principal of spark timing (retarding or advancing) is the same for both systems. Can somebody verify this?

Also, note that cruising speed is attained by fully advancing the throttle until on plane and then backing down the throttle a bit. This allows the throttle plates to close just a bit while keeping the spark timing fully advanced. Joe Reeves taught me that one.

Click to expand...

Thanks for this detailed guidance for this newbie.
I have gone through the sync process one time today and I am getting ready to go through it one more time. The motor still fires and seems to be okay but there is no way for me to test acceleration in a tub however I tried it once and it still seems to sputter. I also still have strong smell of gas, but when I put my hand over the exhaust and then smell it, it does not seem to smell of gas, but the tub really smells(which could be from before) and there is a whitish cloudy film forming on the surface.

Any thoughts on the gas smell, I hate to got out and start dumping gas again at my friends lake.

Again thanks.