Find Top Dead Center

Fasten the degree wheel to the crank.
Take a stiff 1/4-inch rod or similar material and sharpen one end to form a pointer.
Attach this pointer so that it rests very close to the damper to eliminate parallax viewing error.
Obtain a stout strip of steel about seven inches long, drill three holes, two for head bolts and one centered on piston.
Put a bolt in the center hole to stop piston movement.
This strip is then placed across the center of  No. 1 cylinder bore and bolted on each end to secure it to the block.
Caution: Be sure that the strip of steel is rigid enough so that it will not be deflected when the piston contacts the center bolt stop.
Incidentally, the positive stop should be adjusted so as to stop the rotation the crankshaft in normal running direction (clockwise) until the piston crown lightly strikes this stop.

Now, radially turn and lock the degree wheel to the crankshaft at 40 degrees before T.D.C. at the pointer.
Rotate the crankshaft backwards to the positive stop.
If the degree wheel reads 40 degrees from T.D.C. you have hit Top Dead Center exactly, and the zero mark between the two 40 degree readings is absolute T.D.C..
However, if your readings were unbalanced, you will have to split the difference (your errors in degrees) by moving the degree wheel radially on the crankshaft.
Then, try again until you get exactly the same degree readings against the positive stop on either side of T.D.C.
NOTE: The lower the positive stop is located below T.D.C., the greater the degree readings will be. 
The results will always be accurate.
T.D.C. always lies equidistant between the two positive stop readings.