(continued topic) 1973 20hp merc....

[ryanc]

Hey guys ordered all parts and waiting for them to get here. I have a question that i will post here--i thought it got lost in all other post.. If you have forgot...I have a 1973 20hp Mercury model200) ... can anyone tell me at what position is the flywheel on the crankshaft, when the No.1 piston is at TDC??? i have no idea??? . I have worked on Johnson outboards before, they have points under the flywheel, this motor has none..I'm trying to understand with a switchbox, how the thing actually fires and runs??weird!!! Any way help would be good wih my problem with flywheel...thanks Ryan C<br />

 

[ryanc]

Re: (continued topic) 1973 20hp merc....

what I meant to say when piston is at tdc what position would the magnets on the flywheel be in reference to providing spark for combustion. I am just trying to understand how it works without points. thanks again for your thoughts

 

[ryanc]

Re: (continued topic) 1973 20hp merc....

Need some help here guys??!?!!<br /> ryan c

 

[Clams Canino]

Re: (continued topic) 1973 20hp merc....

The problem is, without having one to look at - I don't know. <br /><br />I always mark flywheel parts because I've seen too many people bit by this very problem.<br /><br />-W

 

[ryanc]

Re: (continued topic) 1973 20hp merc....

Thanks Clams, I marked the top two parts but negleted to mark the Key part. irregardless, physics must apply here in the sense that no spark means no conbustion = no power. I am still trying to learn and understand how the conbustion takes place with the use of a switch box and the relationship of the emf produced by flywheel magnets. Engine timing would be correct only when all is aligned but mechanically and electrically, so if this is true then I should be able to put the flywheel hub(holds magnets) into correct postion on flywheel centerpiece that is keyed to shaft. Rod bolt has three of these motors, how do i get in touch with him??? thanks again for your reply

 

[Clams Canino]

Re: (continued topic) 1973 20hp merc....

Try starting a new post - "Paging Rodbolt!" <br /><br />Or if you want, I can start talking about dingleberry cylinder hones again - that outta reel him in like a fish. <evil grin><br /><br />As for how ADI works. The stator produces a fairly HV AC current that is sent to the switchbox, rectified to DC, and stored in a capacitor. The capacitor is gated by an SCR transistor. The trigger magnets on the inside of the stator induce a voltage in the trigger that is used to fire off the SCR at the right time. The SCR then allowes that voltage to dumo to the ignition coil where it's stepped up to very high voltage. <br /><br />-W

 

[ryanc]

Re: (continued topic) 1973 20hp merc....

thanks again Clams for your help! This really clears things up about how the motor works without points... I also will try your idea of a post to page Rodbolt about one of the outboards that he has... they are just like the one I got. Thanks again Ryan C.

 

[Clams Canino]

Re: (continued topic) 1973 20hp merc....

You could buy one... or just have him look at a stator and describe it in detail. <br /><br />-W

 

[ryanc]

Re: (continued topic) 1973 20hp merc....

Yea i would like to have one because i would have a parts motor... I just bought a powerhead for this motor on e-bay so i ahve a extra one..It would be good to have a whole motor---espically the lowerunit as extras parts.

 

[DoctorCAD]

Re: (continued topic) 1973 20hp merc....

Ryan,<br />Where are you in SC. I have a 1973 Merc 200 that you could use as a "look-at" if you are close enough to make it worth your while.<br /><br />Mine runs fine, just had its first impeller change since I bought it last summer. The previous owner stored it for 10 years, and doesn't ever remember changing impeller! The telltale was strong and warm, so I assumed it was fine.

 

[ryanc]

Re: (continued topic) 1973 20hp merc....

Hello doc, thanks for reply, I am located in north charleston, S.C , closer to summerville.<br /><br />First time rebuilding motor and manual doesn't show alot of pictures, such as flywheel from underneath(relationship or positon of magnets to the Key on flywheel) Anyway, looking for some help with that and possibly getting even a broken motor for parts or that I can look at to make sure I am getting it back together right. Anyway, you can reach me at remnant333@hotmail.com. This is an adventure for both my son(ryan) and myself- hopeing that it wil be a positive experience for him and build confidence in himself to become a do it yourself fellow.<br /><br />Anyway, let me know more about that 73 200 20hp. Thanks again for your reply. robert

 

[emckelvy]

Re: (continued topic) 1973 20hp merc....

Ryan, here you go:<br /><br />On the outer circumference of the flywheel ring you should find a timing mark. It'll be a vertical line, punched (not just scribed) on the face. It may even have a bit of white paint in it to help see it.<br /><br />I believe we already figured out that the 2 removeable bolts line up with the keyway. With the flexplate bolted to the center hub (don't think it makes much diff at this point how the flexplate goes), and the keyway pointed AWAY from you, the outer ring of the flywheel is properly positioned when the timing mark is just to the LEFT of the centerline of the flexplate bolt that lines up with the keyway.<br /><br />Hope this helps, I don't have a digital camera or I'd send you a pic. Will send a rough sketch if the above doesn't clear it up for you.......ed

 

[ryanc]

Re: (continued topic) 1973 20hp merc....

This clears things up more than they were. Starting Tuesday afternoon, we will be putting powerhead back together, so when we get to the flywheel and timing stuff, maybe somebody will have a photo. It may be 2 weeks before we get the linkage adjusted back right and the carb adjustments as well. Will update everybody asap.....Thanks again Ryan C.