Setting the timing pointer - 1986 60HP 3cyl

[schuh]

I am checking the setting of the timing pointer prior to adjusting the timing on the engine. All the threads and even the manuals say to adjust the pointing indicator at the .464" mark on the flywheel.

What I don't understand is why I can't simply adjust it at the TDC or 0 degree marking on the flywheel.

Some have said its better to do it at the .464 point as its furthur down on the cranks rotation and therefore more "accurate". BUT you still have to compare that reading to TDC .... so your still measureing TDC.

I know Merc must have had a reason for doing it this way, but darned if I can figure it out !

Any help greatly appreciated !

PS I'm NOT adjusting the timing here ... just the pointer posiion!

 

[oldman570]

Re: Setting the timing pointer - 1986 60HP 3cyl

It is probly because it takes that long for the electricy created by the stator to travel thru the trigger,switchbox, coils, and wireing for the spark happens in the cyclender. JMO
Oldman570

 

[Laddies]

Re: Setting the timing pointer - 1986 60HP 3cyl

The reason for .464 is it is more accurate that TDC as at TDC there will be 3 to 4 degrees of flywheel travel and when your down the bore at there is 0.

 

[CamaroMan]

You can achieve this without a dial gauge using the piston stop method (like cars, etc)

Either get a piston stop tool OR use a long spark plug that will contact the piston BEFORE tdc..

1. OBVIOUSLY disconnect battery for this..
2. remove plug 1 and insert the stop/long plug.
3. Rotate motor by hand approaching #1 tdc.. the piston will now contact the piston stop/long plug.. make a note of zero on flywheel cover or something (this is before true tdc - which is what we want)
4. Now remove stop / plug and turn motor about 1/4 turn PAST tdc.
5. Now insert piston stop / long plug and rotate motor BACKWARDS until it too gently reaches the stop. Make another mark -
6. Your TRUE tdc will be EXACTLY between these two points.
7. Make sure you do NOT use the long plug AT ALL! You will ruin your motor.

From there you can now accurately set your timing.

 

[Faztbullet]

Uhhh..... this is a 3 year old post, please read forum rules....Thanks