1967 Johnson 6 hp carb low speed needle valvesetting

[bednick]

I DID IT! Motor is running.<br /><br />Replaced fuel pump, rebuilt carb.<br /><br />Let engine warm up running in barrel full of water: water pump works, everything sems ok.<br /><br />BUT when adjusting low speed needle valve for best running found that needle valve was completely closed and motor running well. Opening needle valve 3/4 turn did not make much difference other than more exhaust smoke!<br /><br />You guys have been so helpful thus far, don't forsake me when I am so close to being done.<br /><br />Thx again.

 

[OBJ]

Re: 1967 Johnson 6 hp carb low speed needle valvesetting

Well...one of two things jumps to mind. Either you didn't get the float setting right or you forgot to install the nozzel well gasket.<br /><br />When you set the float, hopefully a new one, it should be set level with the bowl gasket surface.<br /><br />The nozzel well gasket is a thickish gasket that goes over the high speed nozzel before you put the float bowl on.....the gasket could also have broken during assembly.

 

[bednick]

Re: 1967 Johnson 6 hp carb low speed needle valvesetting

OBJ, thank you very much.<br /><br />Pulled carburetor, checked float level and replaced gasket over high speed nozzle. Same thing. Motor runs best with low speed nozzel closed. Also generates lot of smoke which I put down to maybe having too much oil in gas mix.<br /><br />What now? Since it runs well, why bother changing anything?<br /><br />If I have to pull the carburetor again I will, but do you have any handy hints on how to get carb mounting nuts onto the studs? Space really cramped.<br /><br />As ever, tyvm

 

[OBJ]

Re: 1967 Johnson 6 hp carb low speed needle valvesetting

OK...let's look at the cam follower. That's that roller on the carb that rides against the cam under the flywheel.<br /><br />There is a reference line on the cam. When you advance the trottle, the cam moves to the follower. When the reference mark on the cam is at the center of the roller, the throttle plate should just be starting to open. If when your at idle and the cam is misadjusted so that it's keeping the throttle plate open, then the low speed adjustment would have little or no effect. Take a look at it and let us know...<br /><br />Jim.

 

[bednick]

Re: 1967 Johnson 6 hp carb low speed needle valvesetting

Fiddling with that does make a difference. How critical is this setting and how accurate do I have to be? Can I just fiddle with it until motor runs best?<br /><br />Again TYVM<br />Bruce

 

[OBJ]

Re: 1967 Johnson 6 hp carb low speed needle valvesetting

Fiddle with it until you get it right Bruce. This adjustment sets the ignition timing with the throttle plate opening so get it right. Set it just like I posted.