Timing mark Pointer

M Strawn

Seaman Apprentice
Joined
Mar 7, 2005
Messages
38
I have a J100stlesb that I am slowly waking up. Another item that has come up it the Timing mark pointer that is held on with a screw. Mine is loose. Before I start the Link Sync procedure I need to get this positioned correctly and tightened down. So, do I just pull a spark plug and use a dial indicator to locate TDC on #1 piston, then tighten up the pointer?
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Timing mark Pointer

They also make a piston stop to do the same procedure. Take your time with the dial indicator.
 

daselbee

Commander
Joined
Jan 20, 2009
Messages
2,765
Re: Timing mark Pointer

O.P., you specifically asked about using a dial indicator....and that is a valid method. However, Boobie hints around at a very important point.

It is important to remember when using the dial indicator, that there is a "lag" or "dwell" at TDC where the piston doesn't really move up or down as the crank journal rotates thru the "topmost" point in the circle of it's travel.
I am not sure exactly, but I would recon there is maybe 4 degrees of flywheel rotation where the piston is not really moving.

You will have to remember to account for that "lag" or "dwell" when using the dial indicator.

As Boobie suggests, the piston stop tool, used along with measurements taken directly off the flywheel is probably a more practical method. The exact procedure when using a piston stop tool is explained in the factory service manuals.

(I once had a piston stop tool installed, forgot/accidently hit the key, engine turned a full revolution and punched a divot in the top of #1 piston, as well as totally eff'ed up the spark plug hole threads in the head.) Just a fair warning.
 

Strawn M

Cadet
Joined
Mar 7, 2005
Messages
17
Re: Timing mark Pointer

Good point about the lag. I will find the middle of that zone and set the mark. Thanks for help folks.
 
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