Re: 70's Model 105 horse starting issues
Your problem is compliance in the control cables. Because of this compliance, the shift may not actually return to center when the control handle is returned to straight up--neutral. Thus: The neutral interlock switch is not being depressed. What you are doing by moving the control back and forth is correct. It works the compliance and re-centers the shift which depresses the button and allows starting.
HOWEVER: Depending upon the year of your engine, the neutral interlock can be mounted on the distributor or on the shift actuating arm down low by the cables.
The neutral interlock switch is a brown rectangle about 2-3 inches long with a white button protruding from the center.
Early 70s engines had the neutral interlock switch attached on the front of the stationary distributor mount. A cam shaped bent piece of metal was mounted on the movable distributor body. This piece was slotted so that it could be adjusted to positively depress the white button in neutral.
Later, (as I was told) the Coast Guard decided this was not a positive enough neutral interlock and Chrysler changed it to the shift arm lever. This switch is mounted below the bottom carb and a cam on the shift arm depresses the button only in neutral. The cam is held to the slotted shift arm by two screws which allow adjustment.
So there you have it. If you get tired of moving the control lever or if it stops correcting the no start condition, then adjust whichever interlock cam you have. Just put the control handle in neutral. Remove the engine hood. Loosen the two screws and slide the cam whichever way causes it to depress the white button. Retighten the screws and replace the hood. Go enjoy your engine.
Also, understand that with the ignition key on, the neutral interlock only functions to stop the starter motor from turning. You can still pull start the engine by wrapping a stout cord around the flywheel--no need to be towed.
