running lean? 260 Sea Ray

[ottawamerc]

Hi guys, quick run down on whats going on. It's a new to me 1987 Sea Ray 268 with a 260 Alpha 1, the engine was blown when I bought it so I had it rebuilt over the winter and after two test runs I'm not happy with the boats performance. It seems sluggish and will only put out 3200 rpm on WOT. The engine was bored out 0.30 over with new everything, plugs, wires etc etc. I pulled a few plugs and they seem pretty lean even though the boat only has less than 4 hrs on it so far. I have checked the fuel pickup and lines and they seem good and while the engine was out I cleaned the carb. I'm wondering if this might be a defective carb issue and the main reason why this boat is on its 3rd engine? On land with a hose connected it will run up to 5000 rpm no problem and the timing is fine but under load, no way! It has a 16X16 prop on it and I tried a 14.5X17 one too with the same result? I also have a Thundercraft Magnum Express 25' with the same engine package and that boat runs like a jack rabbit!

So any ideas on this would be greatly appreciated.

Scott

 

[alldodge]

What drive ratio do you have? Going from a 16 pitch to a 17 pitch is going the wrong direction.

 

[ottawamerc]

I used the prop from my other boat as it works on it and was 14.5 dia the one on the Sea Ray has a 16" dia. How do I find out the gear ratio?

Scott

 

[alldodge]

Many are stamped or printed the ratio on one side of the drive where the stripe would be, along with the drive serial number

If it's missing, the next thing would be to remove the drive and rotate the drive shaft by hand. Then count the number of revolutions the prop turns.

 

[alldodge]

Had another idea
Put muffs on to protect the impeller and turn the water on.

Mark the harmonic damper with white grease pencil of something like.
Put shifter in forward
Now with someone out side counting the revolutions of the prop, jump across the two terminals on the slave solenoid.
One counts the damper revs, the other counts the prop revs.

Do not put the key even in the ignition
The motor will not start because no power is going to the motor

 

[Bondo]

I pulled a few plugs and they seem pretty lean even though the boat only has less than 4 hrs on it so far. I have checked the fuel pickup and lines and they seem good and while the engine was out I cleaned the carb. I'm wondering if this might be a defective carb issue and the main reason why this boat is on its 3rd engine?

Ayuh,..... The fuel system starts are the tank's vent, 'n goes to the cylinders,.....

If the 1st two motors died from detonation, 'n the spark plugs say it's runnin' lean,.....

Ayuh, I'd say ya got a fuel delivery issue,.....

Change the fuel filter, 'n inspect the contents of the old one for water, 'n debris,.....

Hook up a can of fresh clean gas to the fuel filter, 'n try it,....

That leaves the fuel pump, 'n carb to figure out where the issue lies,...

What carb,..??

Did ya Rebuild it, or just clean up the outside of it,..??

 

[ottawamerc]

Ayuh,..... The fuel system starts are the tank's vent, 'n goes to the cylinders,.....

If the 1st two motors died from detonation, 'n the spark plugs say it's runnin' lean,.....

Ayuh, I'd say ya got a fuel delivery issue,.....

Change the fuel filter, 'n inspect the contents of the old one for water, 'n debris,.....

Hook up a can of fresh clean gas to the fuel filter, 'n try it,....

That leaves the fuel pump, 'n carb to figure out where the issue lies,...

What carb,..??

Did ya Rebuild it, or just clean up the outside of it,..??

Thanks for the replys

Yes I did check the vent and it is free and clear, new fuel filter the original had no water or contanimates in it. I disassembled the Rochester carb and cleaned out with Seafoam and carb cleaner but I did reuse all the original parts and gaskets, I ordered a new kit for it today. How could I check the fuel pump for flow/pressure?

Scott

 

[ottawamerc]

Had another idea
Put muffs on to protect the impeller and turn the water on.

Mark the harmonic damper with white grease pencil of something like.
Put shifter in forward
Now with someone out side counting the revolutions of the prop, jump across the two terminals on the slave solenoid.
One counts the damper revs, the other counts the prop revs.

Do not put the key even in the ignition
The motor will not start because no power is going to the motor

Any idea what the proper gear for this package would be? 87 Sea Ray Sundancer 268 5.7 Alpha 1 gen2

 

[alldodge]

They didn't have a Gen 2 in 1987, so it's been replaced. I would hope they installed a 2.0 or 2.4, but you could have any thing from a 1.47 , 1.62 , 1.81 and a couple others. The spec shows it weights 5200 pounds, that's a lot of boat to move with a 5.7

 

[Bondo]

Ayuh,..... I would think the 1.5:1 would be pretty tall on such a big ship,....

1.65:1, or 1.84:1 would be my Guess,....