No acceleration after 2,000 rpm

[Keeganh]

HELP!! I'm new to this forum so I will try and be as descriptive as possible with my limited boating vocabulary, I recently purchased my first boat, a 1974 volvo penta 270 with a 130 horse b20 engine, the boat will idle and accelerated perfect in neutral, and if drive is engaged on hose, once the engine is in the water and under load it will not go over 2,000 rpm... It just Boggs out and stays there, I have replaced fuel, fuel pump, cleaned fuel lines to carb and ran direct from a hose to fuel pump to eliminate any fuel line issues, I have replaced points, rotor, coil, plugs(twice) plug wires, I took off the fire suppression cover and did a full spray of the top of the carbs with sea foam, I'm in the process now of completely tearing apart carbs and cleaning them, I'm at a loss and don't know what to do, there is no exhaust flapper but I was told this would not cause my problem, there is no smoke from exhause, engine is not over heating, gauges all read perfect.

 

[Keeganh]

Sorry boat is a glastron v174 with engine and outdrive described

 

[Keeganh]

Also replaced plug wires

 

[Keeganh]

And also boat sat for a year, was winterized and dew intermixed properly, and 2000 rpm puts me at about 10 miles an hr

 

[MikDee]

Check the firing order of the engine, maybe you have 2 crossed wires?

 

[Keeganh]

The firing order is correct to my knowledge, according to the diagram of the b20 engine I pulled up

 

[Keeganh]

I have noticed a few variations on different years and can't find my exact year any help?

 

[Alan Lloys]

It sounds to me like a typical carb issue.
You probably have the idle jet working but not the high speed jet(s).

I would re-visit once you have the carb cleaned and rebuilt.

The engine will rev up in idle just fine without load as the throttle barely opens when there is no load.
That is why you have the difference between the land test and on water test.

 

[Maclin]

How adept are you st setting the points properly, checking dwell and initial timing and timing advance? Is dwell within specs, and does timing advance properly?

 

[bruceb58]

Make sure you use a dwell meter when setting points on that engine. They are notorious for needing the dwell to be perfect.

 

[MikDee]

Have you checked your centrifugal advance in the distributor, it is under the points, & condenser plate (breaker plate) It has weights, & springs that need to move freely so that you get full advance throughout the engines rpm range. If it is rusted in place, this could be your problem!

To check it, with the engine off, & distributor cap off, you should be able to move the rotor in one direction, about 1/4 of a turn by hand, then the rotor should spring back by itself. If not, take off the breaker plate, (usually 2 screws), and clean, & lubricate the advance assembly till it moves freely. You may need a shot of liquid wrench, or WD-40 to get things going, then finish up with a LIGHT coat of grease on the weights.

 

[Keeganh]

The gap is set at the .020 specs the carbs are soaking in sea foam at the moment and the mechanical advances in the distro move freely

 

[Maclin]

The dwell can be checked without having to start the engine, just need it to spin while the meter is hooked up and ignition is on, it is worth knowing what the gap setting translates to in actual dwell.

 

[Maclin]

Keegan, can you post a pic of a top view of the distributor with the cap off? Wanting to see what style of point set it has, some have "external" spring to augment, could be missing.

 

[Keeganh]

I can't upload a pic cuz it exceeds limits the points themselves are a type of spring but there is no spring attached to the points, the mechanical advance moves but only about an 8th of the rotation, the cleaning of the carb did nothing, the only thing left is the exhaust I'm going to pull it apart tomorrow to check it but if something had built a nest in there it would have blown out by now

 

[MikDee]

I can't upload a pic cuz it exceeds limits the points themselves are a type of spring but there is no spring attached to the points, the mechanical advance moves but only about an 8th of the rotation, the cleaning of the carb did nothing, the only thing left is the exhaust I'm going to pull it apart tomorrow to check it but if something had built a nest in there it would have blown out by now

By the way, the points ARE a spring! Sometimes there's an extra piece of pre-shaped metal in the pkge, that needs to be attached to the back of the points, it needs to be assembled (made of spring steel) that reinforces the points pressure. Also, If you take off the breaker plate (2 side screws) then you can see if the springs, & weights in there maybe binding, and not opening fully.

Don't be complacent, and move onto other things, there's no way to do this diagnosing 1/2 assed, be thorough if you want to be safe, and responsible for you, & your family, or friends.

 

[bruceb58]

The gap is set at the .020 specs

Set it with a dwell meter.

 

[Keeganh]

I will try being more precise with a dwell meter, I have removed breaker plate and the spring loaded advance opens and closes, I lubed and moved the advance a few times and it seems to be opening properly and retracting properly

 

[Keeganh]

I set the dwell with a meter and it is at .020 on the dot, mechanical advances move just like the new distributor I looked at that was the same model number. Still no change.

 

[Keeganh]

So after everything, this is what I'm at, the butterfly valves are never opening after the engine heats up thus keeping the engine choked, is this a sensor or are my dual solex 44s mechanical