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Old 06-24-2010, 12:19 PM
leathermang leathermang is offline
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Join Date: Sep 2001
Location: central Texas
Posts: 17,281
Here is the procedure for finding the top of a piston movement...
You put something on the crank which can be marked on... and a pointer to that location..
Then you put the dial indicator on the piston top... hand turn through a couple of strokes and find the spot that looks like TDC... then on the next stroke mark a place on the crank and note the reading on the indicator... then continue the movement of the crank slowly until you find that distance movement on the downstroke... mark that place on the crank..
Half way between those two marks is the TDC movement of that piston... remember that happens twice per four cycle stroke.. so other things must be considered if you are needing TDC ON the Compression stroke for anything.. like IP timing...
The reason it is done this way is that at TDC the actual movment of the piston is way too small to tell when the crank throw is at the exact top spot. So you bracket it and take the distance half way between your measurements going up and down.
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