1959 QD20 10hp running rough

[Revelation]

I was given a 16ft jon boat with a 1959 Johnson QD-20 Seahorse 10. It had been sitting for over 5 years with gas in it. I cleaned out the carb, ended up rebuilding the carb with new synthetic float, it still wouldn't run. I replaced plugs, and I took the view port off the points and reset them to the .020" that is marked on the head. (Everything inside view port looked shiny and new with no corrosion.) I managed to get it started with a little starting fluid and lots of pulling. Ran well for 5 minutes at idle after I set the slow idle adjust on carb to where it is running smooth, but when I tried to adjust the fast idle on carb, I could not get it running smooth. At full throttle, it doesn't appear to have much more power than at slow idle (in or out of gear). I have not tried a compression test, yet. My next attempt at getting it running is going to be using SeaFoam to clean out the engine.

I had written this project off, until I was bored this past weekend. Since, I got it running, although roughly, my motivation is revived. Any help would be great!

 

[Revelation]

Re: 1959 QD20 10hp running rough

I reviewed the carb adjustment directions. When adjusting the carb, I started by adjusting the low idle valve. Instructions say start with high idle valve. Would it make a difference? Perhaps this is why I can't seem to get the high idle adjustment correct.

 

[lindy46]

Re: 1959 QD20 10hp running rough

Compression is the first thing to check. No sense pouring money into a motor with poor compression. If compression is good, check spark. Make sure both coils are good. You've already taken care of the carb, so if it idles reasonably good, take it out on a lake and open it up. Then adjust the high speed needle for optimum speed/performance. Finish off by slowing down to a troll and fine tuning the slow speed needle.

 

[jonesg]

Re: 1959 QD20 10hp running rough

I have the same engine, same yr.
Been working on it on and off, I poured seafoam right in the cylinders and left it to soak, compression doubled.
Both coils were falling apart so I replaced and did all new points, condensors and plug wires.

where did you get the carb kits and floats?

I have good spark now, have to give it a test run yet.

 

[Revelation]

Re: 1959 QD20 10hp running rough

I got the synthetic float and new glass bowl from marineengine.com and the rebuild kit for carb from iboats.com. I bought the gasket kit for the original fuel tank through vintagemotors.com. All parts ranged from $10-$30.

 

[tmcalavy]

Re: 1959 QD20 10hp running rough

Gently seat both high and low speedle needles. Back the high-speed needle out (CCW) about 3/4 of one full turn, back the low-speed needle 1 and 1/2 turns out (CCW). Run it up to speed and adjust the high-speed needle 1st, then throttle down and adjust the low-speed until it runs smoothly. Best to do this on the boat/water.

 

[jonesg]

Re: 1959 QD20 10hp running rough

I got the synthetic float and new glass bowl from marineengine.com and the rebuild kit for carb from iboats.com. I bought the gasket kit for the original fuel tank through vintagemotors.com. All parts ranged from $10-$30.

thanks for the PM you sent, much appreciated.

 

[Revelation]

Re: 1959 QD20 10hp running rough

I adjusted both carb knobs to where it was running good in a drum. I had to take it for a run on the water. The river was too high, so I took it to Kinzua Dam. Once on the water, it ran almost perfect. I ran it at WOT and decided I needed to make a minor adjustment. Went too far and it shut off. No big deal, until my third pull and the rewind spring broke. I found part number (sierra 18-6501) and ordered it. Now I am out of commission until parts are delivered.

The trip on the water was a blast! We are having isolated thunderstorms with flood warning, but a sunny break came along. I couldn't wait for another day to do a trial run on the water. My 9 yr old girl said that she wanted to go, too. That lead my 7 yr old girl to want to go, so she wouldn't miss anything. My wife reluctantly tagged along. We just got on the water and it started to rain lightly, we pushed on. The heavy rains came when we were about 3/4 mile out. I messed with the carb and it shut off, then the rewind spring broke. We putted back on the trolling motor with the boat filling up with rain. We made it to the dock, but were soaked. After getting dry, we all laughed about the trip.

 

[KB1]

Re: 1959 QD20 10hp running rough

Good eve!

Sounds like you had what REAL river rats would call a fun outing!! Most today think it needs trading in and get a "reliable" engine! Yeah!! Right!!

If you all had a laugh and enjoyed what was happening, then you are a tight family and know how to really have fun.

Happy boating and living!!