OMC Flywheel difference

[Valv]

I have a 1976 Johnson 115hp V4, I was wondering if flywheel is different than a 1989 90hp.<br /><br />Reason is, I replaced all ignition parts with a 1989 90hp, motor runs great but idles very high (1800/2400rpm.<br />Somebody suggested that trigger rod to throttle lever might be stopping it from returning all the way back, but I had it completely against rectifier post and still no change in speed.<br /><br />I tried to completely disconnect all cables and trigger rod, and didn't change anything.

 

[jegervais]

Re: OMC Flywheel difference

The flywheels are different. The orientation of the sensor magnets could account for your excessively high idle speed - basically the ignition timing may be way advanced.<br /><br />-John

 

[Valv]

Re: OMC Flywheel difference

John,<br /><br />Are you sure 100% ??? That's what I thought all along, but I wanted to hear it from an expert, I think sensors inside it are different than older version, that could be only logical explanation, in fact I already sheared 2 crank keys starting it.<br /><br />Now I have to look for a flywheel (and I had the correct one....I sold it )

 

[Solittle]

Re: OMC Flywheel difference

Valv - Let me start out by saying I ain't sure about nuttin. With that said seems to me you got a basic timing problem. The timing marks on your flywheel may not be in the correct orientation to the other components. You MAY (note the caps) be able to time your motor with the flywheel you have even though the marks on the flywheel are not in the correct place. What I am saying is that timing is relative to the number of degrees the spark is supposed to happen relative to top dead center of #1 cyl. Get or borrow an OMC V4 manual for (not sue which year in your case). Anyway the procedure is to find TDC of #1 relative to the pointer (not the flywheel). You then can then check the timing even though the scribe marks on the flywheel are in a different place. I know this is not described very well but think it through. By the way the timing for my 1987 OMC V4s are 28 degrees before top dead center. You may have to play with this a bit for your motor if my thoery is valid.<br /><br />I hope for your sake that others chip in on this and validate what is in my head on this or steer you in a better direction. Let us know as you got me curious.

 

[Hooty]

Re: OMC Flywheel difference

The throtle pick-up timing for the '76 is 4* BTDC and 24* full advanced. I'm bettin if you can get the timing to that 4* throttl p/u, you've got it whipped. Like SoLittle said, you may have to go back and re-locate TDC on the flywheel.<br /><br />g'luck & c/6<br /><br />Hooty

 

[Valv]

Re: OMC Flywheel difference

I understand very well what you are saying, I din't even go to the timing check yet, since I believe problem resides in flywheel.<br /><br />The trigger sits inside the 4 posts holding stator armature, and it rotates partially counterclockwise to change timing. With this set up trigger is resting all the way back against post closer to heads of motor, and cannot be moved that direction anymore, I can slide it forward (folowing throttle lever) as much as I want (till next stator post), but the starting point is already way too advanced.<br /><br />I hope I explained situation.<br />Other way around could be installing flywheel in differnt position on crankshaft, but this will include cutting another shear key slot in it (way out of my capabilities and not worth it).<br /><br />The reason I point to flywheel is location of sensors underneath it, if newer ones have sensors positioned slightly different, it will change timing in relation to trigger position.<br />Unfortunately I don't have another V4, I only have a V6 1989 and I rather not mess with it (runs very well).<br /><br />My question was also pointed to anybody that can have both flywheels on bench to look and see if underneath they are different. I am trying not to spend a fortune replacing original ignition parts when I have here some newer and in good conditions.<br /><br />Val