1967 Johnson 40hp rough idle/ ignition or carb??

[cchildress142]

I have a 1967 Johnson 40hp RDSL-29e. I just disassembled, cleaned and put in a new carb kit due to a sticking float. Now that it's back together it won't idle without "coughing" and choking down. I've set the low speed needle adjustment per the manual (seat slightly then back out 1 1/2 turns). I spent a little time trying to tweak it 1/4 turn at a time in both directions, leaner and richer, and having no luck in getting my smooth idle back. I took it out to the lake Tuesday for an hour or so to see how it ran at WOT. (if your familiar with this particular motor you'll know most came with Type II carb with a fixed orfice but mine is the less common Type II with high speed needle adjustment). It ran smooth at WOT but not at full power. I could tell that it wasn't running at full blast like it used to but due to being alone I couldn't adjust the high speed needle (bow drive stick steer).
My question is do you guys think its just a matter of keep messing with the needle adjustment to get my idle back or should I look to the points, coil, etc....?
Let me also throw this in. A buddy of mine who is mechanically challenged tried to help out when I wasn't there by changing spark plugs. I've checked the gap on them but he doesn't know if he got the two plug wires back on in the right order.
I'm fairly handy around a wrench but new to the old outboard world. Any help is greatly appreciated!!!! It's time to go fishin!

 

[racerone]

If plug wires are switched it would not run at all.-----Do a compression test first.---Then check if spark will jump a 1/4" or more.----If the 2 coils are factory original you need to install 2 new ones.-------Is the throttle opening at the correct ime and not too early ?

 

[steelespike]

Coughing(sneezing) Is a classic lean condition. The 33 is listed at 3/4 turn for high speed and
40 idle adjust is 1 turn out. I don't think you can get the idle right until the high speed is set to the final setting.
If idle continues to" sneeze"try opening the high speed a little.But you do need to get it set right before trying to do the final idle adjust.
Older 40s up to 63 were 1 turn for low speed, Initial for high speed is 3/4 turn open.
those settings are for 30,35 and 40 with a high speed adjust.
If the wires were on wrong it wouldn't run.

 

[cchildress142]

Ok. I had forgotten to mention that I already set the high-speed needle at 3/4 turn out. I'll reset the low speed at 1 turn and check the fire on the plugs. I believe the points and coil were just changed before I bought the boat in December. I've never done a compression test before. I'll check with my local parts store and see if that something they will loan me for the day. Sorry for the stupid question Racerone but i'm not really sure what you mean by "is the throttle opening at the right time"?
Thanks for all the help guys. I'll be getting back on it this evening and post an update.

 

[F_R]

Carburetor and magneto must be properly synchronized for it to run right. Takes a lot of typing to explain the whole thing, but for right now, I think you need to check the carburetor pick-up point. Note to the left of the roller that opens the carburetor throttle, there is an upward pointing arrow. There is a mark on the brass cam that operates the rubber roller. When the cam mark is aligned with the pointer (NOT the roller), all the slack should be taken up and the carb just barely ready to start to open.

 

[cchildress142]

F_R I see exactly what you're talking about. My next question is how do I adjust it if the Mark isn't exactly lining up with the pointer. I have turned the flywheel slowly and can never find a point where they line up exactly. The mark is just to the port side of the pointer when it gets closest. I stopped it at that point and took up the slack in the roller (which there was a lot of). I haven't had a chance to put it in a bucket of water and try it yet though. Also haven't had the chance to check compression yet.

 

[racerone]

That motor came from the factory with a fixed high speed jet.---You have to wonder why someone would install an adjustable one ?---Saw that on a motor that had scored pistons and broken rings.

 

[cchildress142]

Yeah my thoughts too Racerone. Before i had the problem with the float sticking though, it ran like a champ all through the end of duck season.

 

[Willyclay]

BTDT with my RDSL-19. Cleaned the carb three times before finally using a pick to scrap the hard crud out of the low-speed passage. Was still idling great went I traded it away many years later. It is usually the simple stuff. Good luck!

 

[cchildress142]

Finally got a chance to get the boat on the water and make some adjustments. Double-checked the needle settings and started from there. I've got a smooth idle back after some tweaking and running better at WOT. Still not quite running 100% WOT but i'm sure some more tuning will get me there. Thx for all the help guys!!!!

 

[Willyclay]

Attaboy!