What is the effect of the flywheel being in the wrong position?

I recently replaced the stator, trigger assembly and flywheel on my 1986 Mercury 75HP. It's a project motor that had some mysterious and intermittent no-spark occurrances. So I threw as many ignition parts at it as I had on hand.

Motor ran smoothly before I swapped the parts, with a nice steady idle. But since the swap it runs like crap. Super-high idle that I cannot bring down, and it's running extremely lean. I fear I may have re-installed the flywheel incorrectly. I admit not paying attention to the "compass" position of the flywheel when I pulled the old one off and put the new one one. I just set it back down on the splines, thinking it didn't matter where the magnets are.

I now know that the position matters for timing reasons, but "IF" the flywheel is off by a little or a lot, what would the effect on the motor be?

Feel free to call me out for being naive about the flywheel. Deserve it totally.

If it was a splined crankshaft then there is one tooth that is missing.----You can not install the replacement in the wrong position.-----Unless of course you did not look and used brute force !

Outer magnets position do not matter......

racerone said:

Unless of course you did not look and used brute force !

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I definitely did not look, just plunked it down on the splines. I was happy that it wasn't the shaft/key situation, so I just put the flywheel on any old way. Yes, rookie move, but that's what I did. I'll pull it off in the coming days and double check, but my original question stands: how would the motor behave if the flywheel was not replaced in the exact same? Any differently? Thanks.

I believe there are magnets on the hub of the flywheel.------Those have to do with timing of the spark.-----No doubt you know what that means !

If that's the motor I'm thinking of, the flywheel is attached to the hub by 8 bolts. The outer portion can be off if someone repositioned it incorrectly. If so, when attempting to time it the WOT set point will be off a mile.

Jeff

fastjeff said:

If that's the motor I'm thinking of, the flywheel is attached to the hub by 8 bolts.

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I never touched the bolts or took the flywheel apart, just lifted the whole thing off with a puller. My thought is that I replaced the flywheel with no consideration to it's position. And I was wondering what the effect on the running motor would be if the replaced position was off, even by a few degrees. Or would it even start?

You really cant install the center hub wrong unless you force it ..then flywheel would be wobbly. The outer ring can be installed wrong but only thing is timing decal will be off. A motor will start and run even if a could of degrees off. Running lean will make em idle high. Make sure you didn't break the throttle slide arm on front of block as it can hold carbs open..

..."I never touched the bolts or took the flywheel apart, just lifted the whole thing off with a puller."

I meant someone else might have.

Jeff

PS: Started a triple up backwards once--it backfired, started rotating the wrong way and kept running! So much for the flywheel having to be in the "right" location.

**UPDATE** I pulled the flywheel and sure enough, I had re-installed it incorrectly. I remember now that when I put it on a couple of weeks ago, I just sat the flywheel down on the splines, got the nut started, and hit it with an impact wrench. Yes, I'm an idiot.

But after I replaced the flywheel correctly, it started first pop and now runs nicely and idles properly. The lesson I learned: Guess what? It matters how the flywheel is oriented!

And in case you're wondering, this is what the shaft splines look like when you force a flywheel down in the wrong position. Lovely.

Ouch!

Jeff