1974 50hp Johnson

[smilingtom]

I purchased this motor not running, and I haven"t been able to get it to start. I rebuilt the carbs, checked spark it fires good. Compression is 150 on each cylinder. I can't seem to get gas to the plugs, like its not flowing thru the engine. I can put my hand over the carbs and it has suction. I even put gas in the cylinders and it didn't fire but it did backfire thru the exhaust. It makes me think the timing is off 180 if thats possible. How do you get the timing close without it running?

 

[Joe Reeves]

Re: 1974 50hp Johnson

Backfiring thru the exhaust is normally caused by either having the coil wires reversed OR the flywheel to crankshaft key has sheared due to the flywheel nut not being torqued down properly (105 foot pounds).

If a sheared key, clean up the tapers of the crankshaft and flywheel, then install the proper key (307480), having the outer edge of the key vertical with the engine, NOT aligned with the C/S taper.

If you didn't manually clean OR at least make sure that the high speed jets are thoroughly clean, do so. Jets located in the bottom center of the float chambers.