Proper full throttle rpm for a 1956 lark 30 hp

[wrfalpacas]

Hello, I got my boat and motor finished, it's a 1957 Starcraft SkiChamp 14' aluminum I restored with a 1956 Evinrude Lark 30 hp that I re-built. I recently had it at Webster Lake in Indiana at the AOMCI MOB meet. She would make 20 mph at 3100 rpm via tiny tach with the prop that came with the engine. What is max rpm for this engine, and what is a good idle rpm to expect? I also have a michigan wheel 12 by 24 prop I might try. Any reccomendations?

 

[Mas]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Don't know...but you've a very nice boat/motor!

Mas

 

[wilde1j]

Re: Proper full throttle rpm for a 1956 lark 30 hp

I am guessing here, 5000 to 5500 @ WOT. Liquid Nirvana on Webshots has copies of old OMC docs going way back and has the original sales brochure for your motor, which would have the HP @ RPM data. Set idle for ~ 650 RPM in gear in the water.

See if this link works for you:
http://rides.webshots.com/photo/2768684510091848696jQePiz

 

[F_R]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Full throttle operating range is 4500-5000 RPM, per the Evinrude book. Personally, I'd shoot for 4500. You are lugging it badly at only 3100. Either that, or your tach is wacko.

 

[wrfalpacas]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Ok, so I changed props from one marked J 35 to a michigan wheel 012024 and replaced the plugs with a set of NOS Champion J6J 's. My rpm is up to 3800, and it idles down to about 750. The motor has new wires, points and coils. I also rebuilt the carb. (This was my first time at working on an outboard -actually working on a internal combustion engine in general). Any further suggestions?

 

[rolmops]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Your prop is right for your boat,You may try to set the trim one hole higher thereby coming up on plane a bit better.that should bring your rpm up to where it should be

 

[wilde1j]

Re: Proper full throttle rpm for a 1956 lark 30 hp

WOT RPM still way too low.

 

[Chinewalker]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Is your boat heavier than it looks? Might want to go down in pitch a little bit. You definitely want to be running just the far side of 4500 RPM. Any less is hurting the engine. I would also think you would be getting better than 20mph. Can you get another tach to verify the reading?
- Scott

 

[wrfalpacas]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Ordered a MW 012023 to try (10-3/8 dia 11-1/2*pitch) as well, will try changing the pin setting. Tach is a tiny tach digital, so i am pretty sure its accurate. could the gap on the pionts being off a little cause this? I don't remember how close to .020 i got when i set it?

 

[wrfalpacas]

Re: Proper full throttle rpm for a 1956 lark 30 hp

I took the recoil off and checked the points, they are a little tight at .020 but I can get the gauge in between them, how tight is tight enough?

 

[F_R]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Points gap affects the timing, but not enough to make much difference for what we are discussing here. The proper way to set points is with the special timing fixture tool, but realizing that most people don't have one, they simply say to set them at .020" which is close enough to be in the ball park. If you were to set them with the tool, then check the gap, you would probably find them to not be exactly .020".

I guess what I'm saying is that as long as it starts and runs well, that is not affecting your RPM enough to be concerned about. It's all about prop and load.

 

[wrfalpacas]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Took her out again tonight. 1 click up on the trim bar got me an extra 5 mph (25mph) and easily up on a plane. Rewound my tach wire, now i am getting funky readings on the tach 350rpm up to 2300rpm, my guess is it is reading 1/2 of true so that would correlate to 700 slow idle to 4600 WOT. I will have to try another click on the trim next time I go out.

 

[rolmops]

Re: Proper full throttle rpm for a 1956 lark 30 hp

Took her out again tonight. 1 click up on the trim bar got me an extra 5 mph (25mph) and easily up on a plane. Rewound my tach wire, now i am getting funky readings on the tach 350rpm up to 2300rpm, my guess is it is reading 1/2 of true so that would correlate to 700 slow idle to 4600 WOT. I will have to try another click on the trim next time I go out.

Make sure that the ground wire of your tinytech is hooked securely on to a very good ground,that should stop the weird readings.Unless you have a button that makes it switch between 2 and 4 stroke readings.
Be careful not to bring that engine up too high.One more hole is probably fine,from there on it may start cavitating in turns.

 

[Throckmorton]

Hello,

Im quite certain I now have this boat and need some information. My attempts to make contact through WRF Alpacas have been unsuccessful and Im having difficulty finding any other contact info. Can anyone help?
Thanks
Rich

 

[oldboat1]

Gather you've tried a pm? (may not be active anymore). You might try the AOMCI site and see if you can track down the local chapter from info in the first post.