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1971 Johnson 60 HP rebuild problems....

M

Monsterboas

New member
So let me throw some information out first of all my name is Robert and I have been working on this Johnson rebuild for some time now, absolutely love this engine but starting to hit my frustration point....Here's my problem

Over the winter I removed the powerhead, installed new pistons, every single gasket on the powerhead, thermostat, cooling pipes, and water pump. I got everything assembled about 2 months ago and first had a issue with no spark. Well I resolved this issue (hope this is still not a issue) but now I can only start the engine with a touch of throttle body cleaner (I know naughty me) and the issue I'm having is the engine will ONLY run at high throttle. As soon as I attempt to decrease the RPM's she just shuts down. I can start it again but with the same results. I know there is ALOT of professionals on this forums so please give your input.

Sincerely,
Desperately Frustrated
 
Starting procedure: Pump fuel bulb up hard, Apply a slight bit of throttle, Crank engine and push the key in (or engage toggle switch) at the same time to close the choke butterflies. When the engine fires/starts (normally within 6 revolutions), release the key so that it falls back to the run position.


Did you completely dismantle, clean thoroughly, and rebuild each of those three carburetors? If not, do so.

Did you make sure that the brass high speed jets located horizontally in the bottom center portion of the float chambers is absolutely clean? Use carefully a piece of single strand steel wire as solvent just doesn't do that job properly.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

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I dismantled the 3 carburetors a couple different times and used compressed air to blow the orafaces out. I did not replace any parts on the carburetors when I rebuilt the powerhead.

I cant set the idle on it until I can get it to idle, so whats my next step?
 
Before the rebuild someone may have adjusted the idle stop screw in order to keep the motor running.----------Back that screw out and see if that helps.
 
The floats were set flush with the body of the carb, did that according to float recommendations. Yes I am setting the idle air needles. I can adjust the needles and it would smooth out only on high idle. no I did not completely rebuild the carbs just dismantled them, cleaned them and reassembled. I plan on getting a rebuild kit, found a great deal for the rebuild kit. No I did not surface the flange when i had them off but it sounds like I will need to do so and yes I did install new flange gaskets. I will remove the carbs for the mean time until I get the rebuild kits. I will dismantle the fuel pump while I am waiting for the rebuild kits.
 
Thanks for your advice, I want to try to get it on the lake this weekend to see if it will even start with back pressure. I am fairly confident it will, I will adjust when its warm. This project has got me fairly frustrated but I refuse to give up!
 
There is only one idle stop screw !---Find that screw and back it out so that throttle / timing will go back far enuff to slow the motor down.--Initial setting for slow speed idle mixture screws is at 5/8 turn out from gently seated !
 
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Ok guys as I get time to think about the motor more and more.....would the motor run if I had the spark plug wires on wrong? I completely dismantled the stator and distributor for inspection and after a few months I couldn't remember the correct locations BUT I am fairly confident they are on right but not 100% sure. I am sure I will have other things that come to mind so please bear with me.
 
Racerone, I can see the throttle/timing base move accordingly and can see it move back when attempting to idle, one other question I had, I am not 100% sure but is there any particular placement of the rotor? So it goes timing base, rotor, stator/distributor then flywheel.
 
There is a notch in the crankshaft and the rotor key / tab must fit in it.-----I believe distributor cap is marked 1 2 or 3 for the wires to screw in.
 
Did you by any chance change this measurement or cam to roller alignment?

75_70HP SYNC LINKAGE1a.jpg
 
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