1971 Johnson 50 Low Timing

[lowebo]

I have a 1971 Johnson Electric shift 50 my issue with it is the timing at idle is retarded Aprox a 1/4inch ATDC so there is no number to read. The only way I can get it to advance is to raise idle way to high and is the same spining it with the pugs out. A little history on the motor is I acquired the power head (all but lower unit) thru a friend because he knew I had a 1972 50 so I took two and made one using my original lower unit. The power head has a awesome 170psi on both cylinders checked by two gauges.

I replaced both coils and power pack and rebuilt both carbs dipped in Carb acid blown out ...master kit put in..ect,on a side note the carbs like 5/8 turn out and nothing more,same as before rebuild and at idle will stall with more which I thought odd(maybe timing?) so I even JB welded the plugs inside and out incase of air leaks but no change. I did the Link/ Synk as described in the 1971 shop service manual I have not checked the key to see if it has sheered and have not been under the flywheel. The timing advances fine to 19deg, it idles fine and go's in gear fine has a slight rough spot on take off but clears out and run ok but feels a bit slower (no tach sorry) than I expected but its on a pretty well loaded boat. So all in all WHAT would make the timing retard that low at idle? Or is it normal?

Thanks for any help!

Matt

 

[kodibass]

Re: 1971 Johnson 50 Low Timing

not sure what you mean about JB welded plugs?, As far as I know the timing is set with the crankshaft key, I would check that key. sounds to me like you might have some kind of low speed jet issues going on, check the hoses from tank to carb & all points in between. I Also would check everything under the flywheel and make sure nothing has vibrated loose.

 

[lowebo]

Re: 1971 Johnson 50 Low Timing

The core plugs blocking off some of the passages that alows you to clean them on the carbs .

 

[Joe Reeves]

Re: 1971 Johnson 50 Low Timing

The idle timing on the 1971 50hp model is 3 degrees, +/- 1 degree.

Make sure that the scribe mark on the cam makes contact with the throttle cam roller when it is dead center with the roller, NOT before or after.

Run the engine (or use the cranking method) and with a timing light and set the timing to 3 degrees (lock it there with the idle set screw). Now, with the engine at 3 degrees, adjust the nylon threaded connector at the cam so that the scribe mark is indeed dead center with the throttle cam roller.

Now, with the idle set screw, set the idle rpm.

NOTE: If the flywheel key was sheared, even slightly, the engine simply would not run.

 

[lowebo]

Re: 1971 Johnson 50 Low Timing

I done everything you said Joe, set timing to +-1 of 3deg and then re adjust nylon yoke so that the cam follower is dead nut center on the roller. But the best timing I can obtain is 2deg which is a heck of alot better than what I had BUT Im 1/2 a turn from being bottom out on the "idle speed adjustment screw".

So is it ok to be that far into the idle screw to obtain correct timing? or am I missing a adjustment in some place or is it another issue causing a incorrect timing read? Maybe a improper timing pointer? It looks as though it has NEVER been moved.

But so far it revs allot better. But the idle seems a tat high but its on muffs.