Merc 500, 1973 Timing Question

[Chinewalker]

I pulled a good one on this motor. Already too much time into it but in for a penny, in for a pound.<br /><br />Background - replaced the block as the first was scorched pretty badly. Never took exhaust cover off replacement block for fear of breaking some bolts. Assembled motor and fire it up. Ran on three cylinders, found water on the #2 plug. Ended up pulling the exhaust cover, breaking four bolts in the process, found a crack in the inner cover. Repaired bolts, replaced inner cover, motor runs much better.<br /><br />Now for my "good one". When I disassembled the motor, I took the flex plate and outer rim off the flywheel hub. Using a punch, I marked it as to where it was suppose to go when I reassembled it - or so I thought. I had marked the rope sheeve in the middle, which of course is seperate from the flex plate and the hub, so now the timing marks are out of whack, even after my best guess for realigning the flex plate to the hub.<br /><br />My question - I'm not far off, as the motor does run, but I think the timing is up too high - the motor falls flat and pings like crazy if I go anywhere above a fast idle in gear. Can anyone tell me where the crankshaft keyway ought to be in relation to the arrow cast into the top of the magneto pulley? OR, can anyone tell me where the #1 cylinder TDC should be in relation to the arrow on the pulley. I'm not going by the line marks on the pulley cap - just the marks on the pulley itself with that cap removed. The manual is useless because it goes by the marks on the flywheel - which of course are out of whack on this one, so I need to find some non-flywheel refereces to work with. Anyone got a "trick" for getting things lined up again?<br /><br />Doh!! Thanks!!<br />- Scott

 

[Clams Canino]

Re: Merc 500, 1973 Timing Question

Scott,<br /><br />While I don't have one to look at. Can't you just put #1 at TDC and then align the flywheel so that it reads TDC - then bolt it up?<br /><br />-W

 

[Chinewalker]

Re: Merc 500, 1973 Timing Question

Thanks Clams,<br /> I just have to take a step back and re-think it through. I can probably figure it out but was hoping for an easy "trick" for getting it aligned, .ie "flywheel key aligned with X, arrow points to Y and slip timing belt on. I worked on the motor most of the day yesterday getting the broken bolts out and exhaust plate back in, so there's a good chance I was just brain fried and couldn't get it straight in my head.<br /> One of these years I'll get smart and find some better fine thread bolts for the puller - the only ones I've got won't reach with the rope pulley in place which is why I had to take things apart in the first place. <br />- Scott

 

[Bear]

Re: Merc 500, 1973 Timing Question

Try these: <br /><br />Timing 1 <br /><br />Timing 2 <br /><br />Timing 3 <br /><br />Hope it helps!<br />

 

[Chinewalker]

Re: Merc 500, 1973 Timing Question

I got it! In my manual it clearly states that there is ONE timing mark on the flywheel and there are in fact very clearly TWO marks on the flywheel. I had the flywheel on correctly, but had the magneto pulley aligned to the wrong flywheel mark. I slipped the timing belt off, slid it over two teeth on the pulley and put it back together. The motor runs beautifully now! Thanks for the input!<br /><br />- Scott