Swapping parts from '72 Merc 500 to '68 Merc 650

[joblo33]

I have a 1968 Merc 650 with a broken rotor and stuck rings on #2 piston. I was looking at this motor and a blown '72 Merc 500 and started wondering if the new style distributor would swap over. They're both 4cyl engines and I doubt the firing would be much different. Does anyone have any experience with trying this? Also, it seems like a long shot, but would a piston and rings from the 500 work in the 650? I could probably find out by looking up the bore/stroke but I figured I'd ask here first.<br />Eric

 

[Laddies]

Re: Swapping parts from '72 Merc 500 to '68 Merc 650

Most 4 cyl. dist are the same on the same year engines, you might have to change the pickup lever on top of the carbs to make it work with engines that many years apart, also some of those engines were driver CD and some were batt CD which would require changing not only the ign, components but also the engine and boat harnesses or at lest rewiring and changing the ign. switch

 

[emckelvy]

Re: Swapping parts from '72 Merc 500 to '68 Merc 650

M650 and M500 are different bore/stroke and nothing inside except maybe the lower crank bearing and misc hardware is the same.<br /><br />You might be able to adapt the 500's Lightning Energizer ign to your 650 with the aforementioned issues. Be sure to use the matching CDI box with the 500's distributor. Also you'd need to use the 500's internal wiring harness and modify the wires as needed to reach. <br /><br />Not necessary to change the external control harness as it has all the wires necessary to run a mag-type, CDI-type, or Energizer-type ign. The difference is in what pins are utilized in the respective motor's internal wiring harness.<br /><br />Both motors have the same 1-3-2-4 firing order, so no issues there.<br /><br />HTH.........ed

 

[joblo33]

Re: Swapping parts from '72 Merc 500 to '68 Merc 650

Thanks. I'll see if I can get that ignition to fit then. I guess I'll have to open up my 65hp parts motor for the replacement piston.<br />Eric