1956 Evinrude 30HP, model 25924 Everything was great, until........

[pro-crastinator]

Hello everyone. What a beautiful weekend to have the boat on the water. I did get to wade in the lake at the boatramp in the afternoon and the water was not too cold but am still glad it was not up to my belt.
Got to run thru a couple of gallons of 16:1 in the 1956 Evinrude 30hp, model 25924 ? that I have been fiddling around with for so long. Wanted to get some feedback from the experts.
Re torqued head bolts to spec. Nothing bad to note but I'm glad I did it again.
Started motor in bucket the day before, and had a 10 second crank to achieve start. Ran fine.
Next morning, Boat ramp, early, (39 degrees f) took 20 seconds to start. Fresh gas.
Turned low speed jet out to richen mix while it was cold.
Idled out to deep water and throttled up to half speed, held it for 10 seconds, all sounded and looked good. Pushed Simplex controller forward and boat began to move out.
Achieved more speed than ever before. Two adults on board, motor was doing what it should be doing.
Happy happy happy. Only regret at this point is that gps app was not started.
After a minute or so of happy, I pushed on the throttle to see if I had it all the way forward. At that moment, motor lost power and initially sounded like it threw rod (which it did not do)
Low speed/ mid speed/ just under plane speed operation was fine and we ran fine in that mode all the way to the dock.
After the initial power loss, I have a video of full throttle, motor begins to lose power and surge, throttle back and rpm goes up.
( I am workng to get the video posted)
(5 miles ish ramp to dock?) burned right at a gallon of fuel.
When at the dock, up on the lift, took a compression test and got 90-90.
Me thinks that I am suffering from crap in carb syndrome.
Plan to remove silencer, carb, and cover plate for reedvalves (which may be suspect as well)
Reed valves have never seen the light of day in 57 years
and the thought that they could be experiencing a high speed flutter may be valid ?
Ideas welcome....... thanks in advance.
-Bennett

Head Gasket replaced, carb rebuilt, impeller, exhaust cover removed/replaced, Intake side port cover modified for mikuni fuel pump, coils, points, condensers, plugs, wires,

 

[racerone]

Not much goes wrong with reed valves !----Never heard of " high speed flutter " problems with them either.---Dirt can get in and hold them open.-------Look at fuel delivery issues if it is a smooth loss of power.

 

[Chinewalker]

Was the power loss abrupt or gradual?

 

[pro-crastinator]

First time it was like instant loss, had to take a step to steady yourself kinda power loss.
Later on, I could come up to about 80 -90% power and wait for it.. 8-9 seconds and it starts to bog, I reduce throttle and RPM increases.
Fuel delivery is a valid concern.

 

[F_R]

Methinks fuel delivery problem too. Mikuni pump? Hmm-m---m-m

 

[pro-crastinator]

ok, which pump would be a good choice?
I have a use for the mikuni on the Johnson AD-12 aquisition from a couple weeks ago.