Top speed with 18hp Evinrude on 14′ aluminum

[johnny]

I get 26 MPH on my 14 foot AlumaCraft with my 18 HP 1957 Evinrude. I weigh 185 pounds.

[wyo307]

Not entirely related but how much more speed are you seeing out of a 25hp or a 30hp of the same erra? I’m thinking the big twins on a 14ft boat vs the 18hp.

[olcah]

My experience is it depends on where you steer the motor from. For a small light boat an 18 HP steered from the rear is near as fast as a 25 hp steered from the front. If you want the most from 18 HP steering from the rear is probably best and lots of fun. A rear steering wheel looks sharp too. I had that setup with a 12 ft boat and new 58 Johnson 18 HP as a kid and often had to turn the throttle back to prevent the boat from flipping over. It got about 26 MPH. If I was real dumb and sat on the transom, it got over 30 MPH.

My 12 footer using rear tiller steer with 25HP is a bullet and I think would be real dangerous at WOT. (Never got it wide open with rear steering. With a 12 HP Gale I got 22 MPH by GPS). Steering 25 HP or 30 HP from the front it is sporty, lively and controllable but definitely slower(26 or 27 MPH by GPS) than from the rear. If you are steering from the front 25/30 HP is ok. If from the rear, you should investigate a 25 HP before going for one.

Individual opinions, boats, heartrates and risk tolerance will definitely vary. 😀

[wiscoboater]

Stephen,
Shoot me a PM. I have a powerhead for you.

[stephenspann27]

Update… My motor didn’t actually fail the leak down test, I re tested with the motor locked at TDC and both cylinders passed. I think I’ve tracked the problem down to a bad crank seal at the top. The top spark plug stays perfectly clean, and the bottom plug gets soot on it. I installed a tiny tac and ran the motor for 3.5 hrs today. The max RPM I get is 3,400RPM.
The reason I think it’s a bad crank seal is because if I spray the top of the block (under the armature plate) with brake clean, the motor will stall. This also would explain the clean top plug (running lean).

Motor running and being sprayed (you can hear the RPM’s drop, didn’t spray it long enough to kill it)

https://www.dropbox.com/s/y44llm7isc6g4 … 2.mov?dl=0

Is this tool the only way to change the seal without taking the case apart?

[Mumbles]

To confirm the top seal is leaking, you can pour some TCW oil or fuel mix on it and crank the motor over with a socket. This has to be done with the mag plate removed. Removing the spark plugs will make it easier to crank it over to.

https://www.youtube.com/watch?v=cXt6fV6Z5rc

You can remove the seal if you don’t have the proper tool or don’t want to split the cases. Punching or drilling some holes in the seal will let you get some screws threaded into it which can then be used to work it out. The bearing is right below the seal so you want to make sure you get any metal chips out before installing the new seal.

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[stephenspann27]

That’s a great tip on checking for the leak. I’ll do that tomorrow.

[dave-bernard]

I would think if you have a leaky seal then when sprayed it would pickup RPM’s.?

[stephenspann27]

quote Dave Bernard:

I would think if you have a leaky seal then when sprayed it would pickup RPM’s.?

That has been my experience on other engines, but there is always the rule that there should be no change in RPM. I’ll try to confirm it with the oil test sometime this morning.

[stephenspann27]

The crank seal is indeed bad. Oil all over everything, including the points, and when I did the oil test, it blew bubbles.

Oil test:

https://www.youtube.com/watch?v=TpW3erYNrv4

[Author]

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