1957 Lark won’t idle

[Nutzferjunk]

Just overhauled a 1957 Lark. Starts fine at half throttle and sounds good but it will not idle below 2800 rpm. What have I missed? I have changed the two line fuel system to a single line. I have spark on both cylinders until the engine stops. I believe it is a fuel issue. In fact I erroneously put the adjustment screws in the wrong holes and it does the same thing! Any thoughts are welcome.

 

[oldboat1]

Top needle comes to a point. Initial setting is 1 1/2 turns c.clockwise from lightly closed. Bottom needle setting is about 3/4 open or a little less.

These are air/fuel adjustments. At the right rear underside of the pan, there should be a plastic screw and spring. This is a throttle idle setting. Open it all the way and use the twist grip to set to idle/slow idle, then set the screw to hold that position. Advance the throttle a bit to start. When warm adjust the throttle idle to the slowest setting that allows the engine to keep running. Between the carb needle setting and the throttle setting, get the slowest running speed you can. Test to see if the engine will shift into gear without stalling (or throttle higher for idling).

Adjustments require back pressure (test barrel or on the lake).

should get you started subject to further adjustment (for high speed mix, requires at or near wot on the boat.)

 

[Nutzferjunk]

Thank you. Let you know the outcome.

 

[racerone]

Describe what was done during this " overhaul " on this motor ?

 

[Nutzferjunk]

New pistons, rings, carburetor overhaul. Check valves at intake were removed. One hole was plugged the other is used for the fuel pump. New gaskets, power head was pressure and vacuum tested with no leaks. New coils points and condensers. Points set to .020. New spark plugs set to .025. New water pump impeller. Lower unit cleaned out new seals as well. Electric choke works engine starts easily. I am a full time two stroke mechanic so I treated the rebuild like a two stroke rebuild.

 

[oldboat1]

Believe the standard connection for a fuel pump pulse is at one of the by-pass covers. Also, the standard plug would be a Champion J4C or J6C, gapped at .030. But you have presumably done a number of these, so have a good idea of what works best for you.

 

[Nutzferjunk]

The plugs are J6C. Gapped to .035. My .025 was a typo. My first marine overhaul. I traded two string trimmers for this motor. Figured it was worth putting some money into. Clean outboards in the ozarks are hard to come by. Most are stored outside with little preventative maintenance done. It is on a ‘65 Starcraft. I am the second owner. The unit sat for 15 years when the original owner had a stroke.