Re: 79 johnson 140 hp problem
Bree... Powerheads do not fail by themselves, something caused the failure. It sounds like whatever caused the failure has not been corrected. As Dhadley has requested, tell us about the rebuilding... who did it, what size was what numbered cylinder(s) rebored, etc.<br /><br />What is the present compression (actual psi numbers) on each numbered cylinder? The spark, with the s/plugs removed, should jump a 7/16" gap on all cylinders with a strong blue lightning like flame (a wide sharp strong snap!).... Does it?<br /><br />The carburetors have not been rebuilt properly. There are no adjustments available to the fuel/air mixture other than changing or drilling out the fixed jets.<br /><br />The proper jets should be: High Speed = .065 - numbers imprinted on H/S jet would be 65C. Slow Speed = .030 - number imprinted on jet would simply be 30. Note that many of these engines run and start better if the slow speed jets are drilled out to .031.<br /><br />Hopefully complete carburetor kits were used in rebuilding the carburetors. The last superceeded number that I have on the carburetor kit is #439076 which would still be available at any Evinrude/Johnson dealership, NAPA, and no doubt other sources. The float should be set as follows.<br /><br />(Carburetor Float Setting)<br />With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (off level) than the other end. And when viewed from the end, make sure it is not cocked.<br /><br />(Synchronization) - Loosen the set screw on the throttle cam roller and back it away from the scribed cam that operates it. Adjust the throttle linkage between the carburetors so that the throttles open and close at the same time. You want both throttle butterflies closed at idle. Now, set the carburetor throttle cam roller so that the it just starts to open the throttle butterflies when the center of the roller aligns with the scribe mark on the cam.<br /><br />The timer base under the flywheel should move smoothly through it's entire range from idle to the full spark advance position (up against the rubber stop of the spark advance stop screw). <br /><br />To check the timer base for sticking (Engine Not Running), spin the prop to align the shifter dog with forward gear and while doing so, put the engine into forward gear. The reason for spinning the prop follows.<br /><br />(Shifting When Out Of Gear)<br />Pertaining to the manual shift models, when shifting into gear with the engine NOT RUNNING, the prop must be spun so as not to possibly have the dog and gear lobes run directly into each other.<br /><br />To grasp this scenario, with your left hand form a "C" with your thumb and forefinger. Now, with your right hand, form a backwards "C" with your thumb and forefinger. Your fingers will represent the dog and gear lobes.<br /><br />Slide the finger and thumb of your right hand alongside the thumb and finger of your left hand so that they overlap. This is the position of the dog and gear lobes when properly in gear.<br /><br />Seperate that position, then butt the tips of the finger and thumb of your right hand up against the finger and thumb tips of your left hand. This represents having the gear and dog lobes directly facing each other. Should you atempt to force the engine into gear with this condition existing, damage to the shift mechanism will surely ocurr.<br /><br />Now, while watching the timer base, slowly apply throttle clear up to full throttle. The timer base should move smoothly all the way up against the black rubber cap that is atached to the end of the full advance spark setting screw. If the timer base sticks, find out why and correct that problem.<br /><br />Keep us informed.
