Mercury 50 HP .464 expained? Timing my 50 HP

[jhawknz@gmail.com]

I have a Mercury 50 HP with flywheel CD ignition Serial number: 0A981915. I am having some difficulty getting it to time out right. I've followed the instructions in the manual to a tee but it just seems off? I am trying to wrap my head around the .464 mark? If .464 is top dead center then what is 0 degrees mark on the flywheel is that not top dead center? When I try to adjust the spark advance screw it seems off by the distance between .464 and 0 degree mark. I can get it to run but its missing. I made some marks on the top of the flywheel to make it easier to read. Can anyone explain this to me? Am I missing something here?

 

[Faztbullet]

.464 is used to align pointer...and its not TDC

 

[jhawknz@gmail.com]

Ok, so I took a dial indicator and I've aligned the pointer its dead on .464 on the flywheel. But when I move the spark advance link I can't seem to get it anywhere near the pointer at 29 degree BTDC while cranking. Firing order says its 1-3-2 on the block by spark plug #1. I would have to move the spark advance link beyond what the screw would allow. So, then I put the .464 dead on the pointer and made a mark where 0 degrees is on the air intake housing. I then tried to get 29 degrees aligned with that mark that I made. It doesn't want to line up either. Am I missing something here?

 

[racerone]

The timing on an outboard like yours is generally set at the factory and does not go out of adjustment.------I am going to say that you should get a dealer to put it back to where it was when it left the factory.-------Sorry if that does not help you.

 

[Faztbullet]

I don't think you did it correctly...install indicator on top cylinder and bring to TDC and zero indicator, back fly wheel off to .464 and then set pointer to mark on flywheel then check timing.

 

[DavidMoore]

Ok, so I took a dial indicator and I've aligned the pointer its dead on .464 on the flywheel. But when I move the spark advance link I can't seem to get it anywhere near the pointer at 29 degree BTDC while cranking. Firing order says its 1-3-2 on the block by spark plug #1. I would have to move the spark advance link beyond what the screw would allow. So, then I put the .464 dead on the pointer and made a mark where 0 degrees is on the air intake housing. I then tried to get 29 degrees aligned with that mark that I made. It doesn't want to line up either. Am I missing something here?

Where was the piston when you set the pointer at .464? @ TDC or @ .464 inches before TDC.
I suspect @ TDC which would result in you trying to set the timing way in advance of where it should be and this is what you describe. Piston should be @ .464 inches before TDC when setting pointer.
The pointer is set in this way only because finding .464 inches before TDC is considered more accurate than finding TDC

excuses if I understood wrong

 

[jhawknz@gmail.com]

Hey David, the piston was at TDC and the pointer is pointing at the .464 mark on the flywheel. I'll check this again today just to confirm.

 

[merc850]

I have seen flywheels that have been disassembled to replace stator and reassembled incorrectly; look for circular marks around the bolts this would mean that it's been taken apart.If you set the piston at.464 and the pointer is off that mark that means the flywheel is incorrectly assembled.

 

[Dark Spark]

Hey - Just chiming in here years later to clarify if anyone is aligning their timing mark. This works on my 1986 Merc 90 ADI Inline 6.

-Run your hose so you don't screw up the water pump impeller, and remove your plugs.
-Then install the dial indicator tool in the #1 plug hole and turn the flywheel clockwise (the dial stops and begins to go the other way). A little skill here.
-set and lock the rotating dial indicator to 0 (indicating the engine's TDC)
-Rotate the flywheel counter-clockwise until you are 1/4 turn past .464" on the dial indicator (about 5 complete turns of the needle). Keep mind you are now going backwards from TDC so the target on the dial is actually at .436 (4 tenths of an inch and 64 hundreths down from TDC will leave the dial indicator at .436 since the dial is going "backwards")
-Now go back clockwise to .464, and align the plastic timing indicator near the flywheel to .464. and proceed to check the timing.

All this said, when I've done this, the mark is maybe only a hair off than if I just align the plastic timing indicator to TDC. And since the low idle timing is a 3-degree range, it probably isn't that critical to use the dial tool. But being dead-on is a good thing.

 

[Dark Spark]

Hey - Just chiming in here years later to clarify if anyone is aligning their timing mark. This works on my 1986 Merc 90 ADI Inline 6.

-Run your hose so you don't screw up the water pump impeller, and remove your plugs.
-Then install the dial indicator tool in the #1 plug hole and turn the flywheel clockwise (the dial stops and begins to go the other way). A little skill here.
-set and lock the rotating dial indicator to 0 (indicating the engine's TDC)
-Rotate the flywheel counter-clockwise until you are 1/4 turn past .464" on the dial indicator (about 5 complete turns of the needle). Keep mind you are now going backwards from TDC so the target on the dial is actually at .436 (4 tenths of an inch and 64 hundreths down from TDC will leave the dial indicator at .436 since the dial is going "backwards")
-Now go back clockwise to .464, and align the plastic timing indicator near the flywheel to .464. and proceed to check the timing.

All this said, when I've done this, the mark is maybe only a hair off than if I just align the plastic timing indicator to TDC. And since the low idle timing is a 3-degree range, it probably isn't that critical to use the dial tool. But being dead-on is a good thing.

Sorry, last bullet should be: -Now go back clockwise to .436, and align the plastic timing indicator near the flywheel to .464. and proceed to check the timing.

 

[WIMUSKY]

Sorry, last bullet should be: -Now go back clockwise to .436, and align the plastic timing indicator near the flywheel to .464. and proceed to check the timing.

Hey Dark Spark.... This thread is over 5yrs old. Please start your own, you can copy and paste all your info into your new thread....
Thanks, Musky