Need advise on RPMs shooting up like 500RPMs w/ new engine

[the brain]

Couple things I should mention

1. the cowl latch cut 3 wires going into the EMM I believe this damaged to current tackometer. I have a spare that came w/ the ETEC (didn't use bc it's white face. an previous tack is the same but matchs the rest of my gauges)on next shakedown runs.

2. both the previous an new ETEC where purposely purchased as 20” shafts this for weight savings.

3.the bottom of the transducer is even w/ bottom of hull per Ray Marine instruction.

4.never had a Mercury hub on either outboard for this vessel.

5. the reason setback is so popular is setting back gets the engine in unaggretated water, I can’t intelligently respond to the air bubbles comment.

6.oil alarm is caused by the resovior being half filled when the hull tilts the sensor thinks theres no oil. another contributing factor is air entered the oil line during derig.steps to resolve are purge oil line w/ primer bulb which is rock hard, or use the automated winterize feature builtin to the ETECs basicely pumps extra oil to coat the inside of the cylinders which helps purge the air. either not that big a deal.

7.now the water I believe that is acutely a overheat bc the waterpump discharge was real weak however ETECs are know for this weak discharge.I will logon w/ evinrude diagnostic sotfware an check the alarms.

8.yes Phil you can see how low the engine already is.which is exact same height as previous engine remember both are 20” purposely purchased 20”. Yes the previous engine an prop have been run though some sand/smut but the prop damage I mentioned was a couple small dings. Will post up a image of this minor ding.
the cupped prop sounds worth looking into thats after I determine the correct pitch. this horsepower level ETEC prefers a 14.25" diameter so that part of the guesswork is done it's the pitch thats needs figuring out.

That water pickup is interesting.these shakedowns are the first for the ETEC remember this is a rebuilt transome an repower rebuilt exactly like for the inboard to out board conversion.

thanks Guys for feedback even the harsh constructive criticizium.

 

[DogCavalry]

You can clearly see the holes here on the front of the gear case. My engine is the HO model. As close to a race engine as Evinrude made, I guess. Still gets water in surface piercing mode. Unfortunately my engine filled up with muscles and barnacles through those holes. I only do 33 knots and under, so not exsctly a speed demon.

 

[the brain]

I've never looked closely at gearcase but think theres one hole plus the speedo water pickup.what engine is that?

 

[baeckmo]

I suspect your geometry is right at the hairy limit of shallow draft for that engine, and it looks like you have already run it through the mud. Prop damage is probably causing ventilation and rev rise, since you didn't have it at first. The cooling thing is a real problem, though. You may need an aftermarket remote pickup for it. It just depends whether you can live with another inch of motor depth.

Found this - WATER PICK-UP KIT, P/N 5006337, 5005124, 5005063 & 5007081 INSTALLATION INSTRUCTIONS | Crowley Marine https://www.crowleymarine.com/d/tech_article/water-pick-up-kit-pn-5006337-5005124-5005063--5007081-installation-instructions

Good info there, Phil!

 

[DogCavalry]

I've never looked closely at gearcase but think theres one hole plus the speedo water pickup.what engine is that?

Yes, my two etec 115's don't have those extra holes. I didn't know what they were until @baeckmo told me.

Etec 250HO

 

[fallguy]

I’m not going to comment as more than the idiot here, as you have great help from @baeckmo

And I mean it sincerely, pay attention to his advice. His contributions are solid; go back and reread it three times.

Baeckmo fails to understand the place of the idiot. I don’t mind it.

but, I will ask as the idiot

Did you suggest you can lower the motor 1.5”? Cuz I believe I read it and it looks like you can come down more.

I suspect you may still spin out, but maybe less. And perhaps you can get more water. Or with the suggestion.

Just another dumb question here as well. Despite the leg looking rather high; have you attempted a slow throttle up sans trim tabs? I expect you’ll overheat, but will you still spin out? I think probably spin still, but did u try it?

All I have are a couple of simple questions, I try hard not to get too far outta my lane; generally.

Afa Etec, they were, yes were a unique engine, but they actually are a bit complex and that made them difficult. I didn’t say it, but many others have. And Evinrude died a business failure after people got nervous about Etec; which is only one of the issues. They are finicky. Who wants an oil alarm on a half tank?

 

[fallguy]

ps

I have a Ray ducer on my boat and put it all the way on the edge. My transoms are super narrow; did the best I could.

 

[the brain]

I should mention I’ve recently rearranged my fuel an oil storage location from stern to midship. I’ve been planning new saddle tanks for a while.


Previous engine had 19 gallon tank on star side 12gallons on port side, oil resovior was aft of midship now is relocated to well forth of midship.


So basicely I’ve relocated about half of the 31 gallons of fuel weight 217LBs an oil probally 20LB total 120LB off the stern.


Previous engine was 383LB new ETEC is 418LB so 35LBs heavier 155LBplus the cantilever effect w/ engine weight.

I also modified the knee brace a bit shaved about 10LBs so minus 10LB. so netting these weights 145LB differnce at stern w/ new ETEC.

I can factor in the weight of the new transom rebuild when I initialy did the outboard conversion each piece of marine plywood weighted approximately 70LBs total 140LBs plus 10LBs of epoxy. I think I could have gotton jipped on the quaility of the new transoms plywood
one plywood was heavy like a normal marine plywood however the 2nd plywood was like half the weight probally 35LBs. so factor in even less weight on stern.lets say 40LBs

I think relocating the fuel lowered the waterline at rest basicely elevating the engine effecting the performance.


Yes I know these weights don’t effect the proper engine to hull height ratio w/ the extra 200LB. but do effect how deep the prop sits in water.


Now I can’t factor in the whole amount of fuel bc these shakedown runs I only had 8 gallons at the stern.


I’m hopping the 1 ½” of downward adjustment will be enough if not I’ll be forced to lower the pod a bit more.

 

[gonzo]

Fuel and oil are not a proper way to adjust trim. If the boat only runs well at a particular amount of fuel and oil, it will run badly most of the time. Ideally the CG of the fuel tank will coincide with the CG of the boat. It should at least be as close as possible.

 

[the brain]

If the boat only runs well at a particular amount of fuel and oil, it will run badly most of the time. Ideally the CG of the fuel tank will coincide with the CG of the boat. It should at least be as close as possible.

yes I agree w/ your logic makes sense. another weight I didn't factor in was the weight of the previous 19 gallon fuel tank on it's own empty weights 20LBs. each 6 gallon tank probally 5 LBs each so theres another25LBs off the stern.
I'll continue to crunch the #s while in the process of lowering the engine.

what is CG thanks

 

[gonzo]

Center of Gravity. If the CG of the boat changes too much it will affect how it runs as the fuel gets used.

 

[Barry]

Fuel and oil are not a proper way to adjust trim. If the boat only runs well at a particular amount of fuel and oil, it will run badly most of the time. Ideally the CG of the fuel tank will coincide with the CG of the boat. It should at least be as close as possible.

Why? (and this question does not refer to the boat inclination at rest)

 

[BlueBell]

Why? (and this question does not refer to the boat inclination at rest)

If I may take the liberty of answering in Gonzo's absence:

Because fuel and oil are variable weights. They are poor ballast as they vary in weight between full and empty.
This is a basic application of principle, perhaps something is missing in translation???

 

[kapnD]

CG is also Coast Guard, you might want to jot their number down…

 

[gonzo]

Not correct USCG is the Coast Guard.
As far as the variable weights, BlueBell answered it correctly. Ballast to trim a boat should be fixed and not variable. Otherwise, it will only run well at a certain volume of fuel and not at others.