Flywheel timing mark help please

[Rovernaut]

I have a 1986 Merc classic 50 ( 45 HP)<br />4 cyl inline.<br />I want to time it and am having all sorts of trouble trying to find the real timimg mark.<br />The Seloc manual goes through the process of describing the timing sequence and the motor must be in gear and the engine running for primary and max spark advance at wot.<br />But when I put my timing light on number 1 cyl ( the top one) My light does not come any where near the markings on the flywheel decal.<br />I am at a dilemma as to what timing mark to read.<br />My primary timing should be betwwen 7 and 9 BTDC. <br />If the 9 deg mark is the one shown on the flywheel decal then I am about a 1/4 of a flywheel turn out!<br />There is also a max spark with 30 marked on it on the flywheel and a few other markings to the left of it<br />followed my a few dots.<br />If I go by the most extreme left hand dots and <br />I accelorate, then the mark changes even furthger to the left and is no where near the 30 deg mark.<br /><br />I am really confused, what is the actual timing mark I should be aming for?<br />I can't believe the flywheel could be out by 45 Deg as there is a key way that it slips into on the crank.<br />Could the flywheel be pulled apart and the timing marks re aligned?<br />Any help appreciated<br />

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[rodbolt]

Re: Flywheel timing mark help please

see that big notch. thats TDC and must be manually verified, the marks to the left are BTDC and the marks to the right are ATDC, big difference,<br /> quite a few motors idle some degrees ATDC and wide open run BTDC.the B is before Top Dead Center of the piston in question and the A is After top dead center.<br /> but first you need to find the point where #1 cyl is at the very top of its travel and verify the timing marks on the flywheel agree with the timing tab when the piston is at its TDC. be aware there are a few degrees of crankshaft rotation that the piston does not move.<br /><br /> so before continuing verify the physical location of all the marks agree with the physical location of the piston your checking.

 

[Rovernaut]

Re: Flywheel timing mark help please

Thanks for the reply Rodbolt.<br />The notch is nowhere near my timing pointer. It is as if the flywheel is 45 degs out. There are a lot of bolts on the top flywheel plate, I wonder if some one at some previous stage has dismantled it?<br /><br />I am still confused by what you say though.<br />If you look at the decal on the right of the big notch, there are numbers reading from left to right, 9 - 3 - 0- 5 -10.<br />I thought that maybe 0 was TDC and 9 and 3 were BDTC and the 5 and 10 were ATDC? and the max spark decal of 30 deg was just the continuation of the BDTC marks from 9 followed by dot increments.<br />As I said earlier the Seloc manual is very vague on timing marks

 

[Rovernaut]

Re: Flywheel timing mark help please

I pulled the flwheel and unscrewed the trigger magnet/flywheel to crank shaft retainer assemblt and spun the flywheel plate to align TDC "0" mark with the number 1 cyl at TDC.<br />I have set the timing ingear at 7 -9 deg BTDC as per manual and at WOT it should be 30 Ded BTDC, however it is much higher than that according to the timing marks.<br />I will have to screw the max timing stop a fair way in to bring it to specs.<br />just for interest I post these pics, 1st one is of the flywheel trigger magnet. <br />The top side has lotsa of screws that hold the pull cord ring and flywheel plate to the trigger magnet ring underneath.<br /><br />second on is of crankshaft top, which has a tapered top with a key.<br />The flywheel has a key slot.<br /><a href="http://photobucket.com" target="_blank"><img src="http://img.photobucket.com/albums/v228/Rovernaut/000_1739.jpg" border="0" alt="Image hosting by Photobucket"></a><br /><br /><a href="http://photobucket.com" target="_blank"><img src="http://img.photobucket.com/albums/v228/Rovernaut/000_1740.jpg" border="0" alt="Image hosting by Photobucket"></a>

 

[rodbolt]

Re: Flywheel timing mark help please

your correct, your pic is so fuzzy I cant see it clear and dont know how to make it smaller.<br /> first you have to bring #1 piston to TDC and verify it with a dial indicator or the piston stop tool. a phillips screw driver will get within a few degrees, the pointer should point within a few degrees of TDC then. if it does not you have a problem.

 

[rodbolt]

Re: Flywheel timing mark help please

first plan is to physically place #1 piston at TDC with a dial indicator through the spark plug hole . then we can address the marks.

 

[Rovernaut]

Re: Flywheel timing mark help please

I have put cyl 1 at TDC and found the flywheel was out. Some one in the past had unscrewed the the trigger magnet /flywheel to crankshaft assembly and not realigned it correctly, thus my timing mark on the fly wheel was out my 90 deg.<br /> I have placed it in the correct postion and have tuned the motor.<br /> All is well now.<br />Thanks.