50's 12hp sea king prop question

[jasonhowerton]

14 foot Lowe lake Jon, when by myself I can get on plane by leaning forward a bit and it will scoot. Once I have 2 more guys in boat, one in middle and one in front, it moves forward quickly but is very slow at wot. My current prop is probably original 3 blade 9x10. Other number on it is 553874.would going to a lower pitch help push me faster with a load? It doesn't seem to be getting all the rpms as it does when by myself, it almost sounds loaded down. I can get a serial number off the motor this evening if that would help. Thanks

 

[Sea Rider]

That's a underpowered engine for that size boat while heavily loaded, a less pitch will better fast displacement speed, will it be able to plane that combo out ? who knows..

Happy Boating

 

[steelespike]

Assuming a healthy motor and no excess weight with one aboard 19-21 could be possible.
Your model number would help.The 15GG9018A is a 51 12 hp full gear shift.
Note the 51 is the first 2 numbers reversed. 25GG9018A 52 12 hp. And so on.
A number of things can help your speed.
The antivent plate (just above the prop) should be about even with the bottom of the boat.
Points should be set for .020. Champion J6C plug set at .030.
Note the condition of the throttle advancement mechanism. Carb wide open at full throttle
Timing not advanced too far or not far enough?

 

[Sea Rider]

OP's requirements is with 3 on board, with one up no problem. Anyway, to get the max out of that 12 HP, need to know factory mim-max wot range, install an induction tach, go for a solo wot spin, check achieved max wot rpm. Will know where you stand right now.

Standard delivered factory props are usually medium size pitched which performs good on lightweight boats. If plan boating with 3 up most of the time will need a prop maximization with less prop pitch to rev around ideal max wot range. Bear in mind that when solo boating OB will over rev, so watch tach and throttle less..

Happy Boating

 

[steelespike]

Motor developed its hp at 4000 rpm Original prop on the 15GG 9018A is a 3 blade 9 X 10,later models use a 9 X 11.and a Different power head.

 

[jasonhowerton]

Montgomery Ward
Model NO. GG90165
SERIAL NO. 65X633915
So 1956 year...
I have had points issues with this motor when I first got it, was able to work all that out, but maybe they have moved or become dirty. Some times at low idle it will almost sound like it drops a cylinder, then regains it, until I give it a higher idle on the throttle. This boats sees the river only a few times during the summer. It definitely seems like it takes a lot longer to get on a plane by my self than last year. I will look at the antivent plate, that was one thing I was never quite sure of if the motor was too low into the water. It may just need a going through again no more than I use it, I really thought it pushed a little better in the past, of course I have gotten fatter, so that doesn't help. lol. Thanks guys

 

[steelespike]

I think you may find that is GG9016B Serial number seems to make it a 56.
These motors share parts with the Evinrude/Johnson motors of the same era.
If the coils haven't been replaced they are overdue.Your symptoms are typical.
You can find these here at iboats.Carb kits as well.But you will need to use the E/J numbers.
Maybe you could post some pictures.If it has a knob on the front that you twist to choke the carb kits may be different.
Does it have full gear shift and tiller control?

 

[jasonhowerton]

No Title

 

[jasonhowerton]

http://forums.iboats.com/forum/engi...oard-brands/392331-12hp-sea-king-trouble-help
Not sure if this link will work. I forgot I had a couple post about this motor on here a few years ago when I first got it. This one has a few pics

 

[jasonhowerton]

Where can I find a manual/specs for this motor? The above link on my last response has a few pictures of the motor.

 

[steelespike]

You might try the guys at www.aomci.org.or watch craigs list or ebay.
12 hp at 4000, 2 1/4 b X 2 1/4 s 17.89 cu. in. gear ratio 12:21 ,3 blade 9" X 11"prop.
Magneto, 2 gallon tank,.approximately 1 hour wot burn time , 66 lbs
.020 point gap,.030 plug gap J6C champion plug.Oil ratio 24:1
Torque numbers in inches,rods,96, crancase 120--144, cyl head 96--120,flywheel 480--540,spark plugs 240--246.
Ignition and fuel systems are very similar to E/J motors.
Always used a single line remote tank.