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1979 mercury 40hp Thunderbolt Timing questions..

V

vaino

New member
hello. I have a 1979 Mercury 40hp "thunderbolt ignition" engine with rope start, and i wanted to install a electric start. So i Went to Scrapyard and bought a Flywheel, starter and startersolenoid out of a 35hp 1985 Merc, It has only 2 big magnets under the flywheel, as in the old one has magnets all the way around. Does this affect something?

Also, i removed the flywheel all the way wrong by removing the 8 bolts.. but this doesnt effect timing, even if the outer flywheel doesnt go on the same position?
- it only affects the timing marks being messed up? in my mind the triggerplate does the ignition timing, and flywheel/stator generates electricity? ANYWAY, i'm very new to the boat engines, actually this is the very first one i have..



Also.. is there anyway this engine is going to start by that specific flywheel?..

-Sorry for my bad english. -Sam
 
fastjeff said:
Fixed the 8 bolts screw up is easy, but you'll need the correct flywheel.

Jeff
Click to expand...

Yeah, but does this mean that the flywheels magnets also have something to do with the timing? i mean, i read somewhere that the triggerplate generates "half" of the timing on high rev? as it adjusts the advance.., and that the magneto's ring generates the other half.. Maybe i should try to remove the starter teeth from the flywheel and attach them to the old one? that might be the only way way to get me a electric starter then..
 
fastjeff said:
I believe that motor has a distributor? IF so, the magnets are only there to charge the battery.

Jeff
Click to expand...

Those were my exact thoughts, yes it has a distributor. Anyways, we already grinded the starter outer ring what has the teeth from the other flywheel, and welded it to the old one.. so that should do the trick. :)

Thanks for the responses, hopefully in few weeks we've had the time to make the wiring to the starter, and built an ignition switch , and safety switches to the gear levers.. It actually started snowing just now, so our hurry is long gone..

Wasnt it that when i install the old flywheel outer ring back, I have to turn the number 1 cylinder to DTC, and then align the wheel so that the timingmarks show from the hole around 0 to 3 degrees?
 
kimcrwbr1 said:
What is the model number of your motor? I believe your getting your years mixed up from what I am seeing the 79 has the trigger, stator and switchbox with separate coils?
Click to expand...


Oh.. I mixed words again. I'm actually getting my bad english skills mix up words in my head.. This doesnt have distributor.. this has the same switchbox as 4860103
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4860103 THRU 5556229
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5556229 (USA) > and all the other components are identic. Ignition coils are on "top of the engine" isnt the switchbox like a "cdi box" out of a moped?

I'm pretty sure it's a 79. I Did once check it with the serial number. I don't have it with me at the moment tho..
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kimcrwbr1 said:
My concern is you say you welded the ring on from the later model flywheel correct, is it the same size as the original or have same number of teeth? Is the starter the same and have the same pinion? Will the pinion fully enguage the ring gear. Yes it has the CD type ignition with a switchbox and a trigger does it also have the charging circuit with a rectifier? You can find all the original parts for electric start and charging system. That engine will be turning 5000 rpms at WOT if your welds are uneven it will shake that motor apart pretty quick. I just want you to be safe when your out there.
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I'm actually not concerned about the welding part, it has been done properly, and the wheel was a tight fit. so, you think i should balance the flywheel? i could do that.
i'm not sure about the rectifier, since i havent seen one there.. as i said it has rope start originally. All the parts fit perfectly, since the 35hp newer motor has the same block etc.. starters pinion engages just as much as the 35hp one's. It would be pretty costly to order parts over to Finland..

Are there differences between models, that they don't have proper charging unit? i have a very good optima yellowtop battery which can handle just fine all the starts i'll need on a trip..
 
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