I?m working on a Mariner 50 hp, 4 cylinder, 2 stroke, electric start, serial # 65428531. Right here is a photo of mine flywheel. Room the numbers left that zero ?degrees BTDC? and also the numbers appropriate of zero ?degrees ATDC??
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2. The Mercury shop hand-operated says to adjust timing in forward gear with engine running and to use a test tank or beginning the boat. Is this because that cooling or go the prop require submersion in water because that resistance while working in forward gear? If just for cooling, can I finish timing adjustments on floor while cooling through a muff (prop gotten rid of for safety)?3. Adjusting the ?maximum spark advance? requires advancing the accelerator in forward gear until the point out on the flywheel check out 32 degrees BTDC. How much force will the prop be generating in ~ this point? have the right to this be done while bound up at the dock, or will I need to be totally free since the engine will certainly be under strength in front gear? OR, are the RPMs low enough when the 32 level BTDC note is reached that i won?t need to worry about how much thrust the engine is producing? Again, curious to recognize if this part of the adjustment deserve to be done v a cooling muff when the watercraft is ~ above the trailer.Thanks in development to all the an excellent people who help me out with expertise this.

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ticondo46Seaman Apprentice
JoinedJan 30, 2012Messages31
Re: Timing: how do I read my flywheel, and also other time questions?At idle, definitely do it through the propeller in the water. With just the muffs on, friend don"t have actually the same ago pressure top top the exhaust, and it would offer you a wrong reading.Don"t effort a WOT adjustment of preferably spark advance with the boat in the water however! at the an extremely least, you space going to obtain covered in splash, and at worst, you will certainly be climbing over the dock! I"m not specifically familiar through your exact form of motor, yet I would say the if nobody disturbed the original factory settings, you have to be OK for maximum spark advance once you"ve got the idle spark advancement right. Alternatively, you have the right to do a max spark development adjustment through the reduced unit in the water, yet the prop take away off. Simply blip the gas towards WOT, have actually somebody host the timing light to the marks and also check it out. Don"t store the motor at high RPM"s and no pack for anything an ext than a 2nd or so!Good luck.
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Chris1956Supreme Mariner
JoinedMar 25, 2004Messages24,641
Re: Timing: just how do I read my flywheel, and other timing questions?Fish, The time marks left that zero is BTDC. Eliminate all spark plugs except #1 and also install these right into their plug wires and also ground them to the block. Now you can crank the engine to collection the timing, and it will not start. Girlfriend may collection idle and max spark advancement in this method in your driveway. Carb mixture adjustment demands to be done in the water, engine warm and in forward.32* max advance is a lot. Because I perform not recognize the year of that motor, it may or might not be right, or quiet recommended.
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Re: Timing: exactly how do I read my flywheel, and also other timing questions?Thanks! That?s a great bit of details to help me out. I simply scanned the 3 pages out of mine shop hands-on which define timing adjustments and also specifications, in instance they will help any of you folks who room gracious sufficient to aid me understand the material.
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1. For my engine?s serial number, the ?primary pickup? timing need to be collection between 2* BTDC and also 2*ATDC. Is this what I want to aim for once adjusting the time at idle speed? 2. Max Spark advancement should be set to 30* BTDC, however should be adjusted at 32* BTDC in bespeak to attain 30* according to the manual. Additionally, the chart mentions 33* BTDC when cranking with starter. Ns gather that if ns do change Max Spark breakthrough in my driveway by cranking through the starter motor and plugs pulled and grounded, I desire the flywheel guideline to review 33* BTDC. Execute I understand the chart numbers ~ above pg 1 correctly? 3. The time light has actually a tiny dial top top the earlier of it because that spark advance. I mean I must leave this at 0*? Would setting this dial ~ above the timing irradiate at 3* then mean that i would change Max Spark advancement so the reminder showed 30* on the flywheel? Sorry because that being together a layman, yet you folks are the ideal teachers!4. I?ve to be doing a totality bunch of occupational to this engine and also figured a time adjustment would be a great measure come ensure that every little thing is collection correctly. I dismantled the throttle lever to lubricate it"s friction points, but did no touch any type of of the protect against screws, so about theory the stop screws should still it is in on target, and also these room what actually collection the timing between the trigger assembly and the mechanical components of the accelerator lever, correct?Thanks again because that all your help! ns can"t give thanks to you enough.
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Chris1956Supreme Mariner
JoinedMar 25, 2004Messages24,641
Re: Timing: just how do I read my flywheel, and also other time questions?With all spark plugs the end (remove prop), except for #1, advancement the throttle until the carbohydrate is just ready to open. Placed timing light v zro development set, crank motor and also read timing. The should match primary pickup spec. Change as specified.Advance throttle fully and inspect that carbs are all the way open. Crank motor and read max advance. I would use 30* BTDC together the spec, because I do not recognize why the time would readjust if the motor to be running.There need to be set screws for minimum idle (Idle stop), max spark development and max throttle. The actuator plate should rotate for adjusting primary pickup timing.
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Re: Timing: how do I check out my flywheel, and other time questions?Thank friend Chris.I"m not certain why it would contact for 33* BTDC once cranked by starter motor but call because that 32* BTDC through engine running. Ns don"t recognize the actual guts of one engine well sufficient to know why that would certainly be specified by the Mercury company manual. I"m likewise in the dark on why 32* BTDC need to be provided to acquire 30* BTDC. I think it"s time for a new thread on the topic, and also maybe someone will be able to say why the digital timing attributes of this ignition mechanism require setup max breakthrough at 32* BTDC to attain 30* BTDC.
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aussieflashLieutenant junior Grade
JoinedFeb 5, 2011Messages1,004
Re: Timing: how do I check out my flywheel, and also other timing questions?Your engine is a 1984 model.Spark advancement characteristics is the very same as my V6 1988.I didnt try to understand it....I simply did as I was told...lol.All my timing to be done in ~ cranking only...much easier.I couldnt imagine do the efforts to adjust max while engine in water???Is that even possible.

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Chris1956Supreme Mariner
JoinedMar 25, 2004Messages24,641
Re: Timing: exactly how do I read my flywheel, and also other time questions?Aussie, i think his engine is lot older than 1984. I think it is so late 60s or at an early stage 70s.