This unique piston stop works on Animal engines with the 14 mm spark plug and
also on the World Formula engine with the 10mm spark plug.
Price $19.95
9:00 til 5:00 central time
Finding Top Dead Center   (TDC)

Install the degree wheel on the PTO side of the engine with the numbers facing
the block. Make sure it's centered   (doesn't wobble)
Make a pointer from a piece of stiff wire and attach it to one of the bolts on top of
the engine.
Remove the spark plug and turn the engine so the piston is all the way up to the
top of the bore. Look through the spark plug hole and get the piston as close to
the top as you can.
Loosen the bolt holding the degree wheel to the crankshaft and rotate the
degree wheel so the pointer is lined up with the TDC mark on the degree wheel.
Turn the engine clock wise about 60 degrees and install the dead stop[ in the
spark plug hole.
From this point on be careful not to turn the engine too fast and crash into the
dead stop.
Turn the engine counterclockwise until the piston touches the dead stop. For
explanation purposes lets say it stops at 40 degrees. Turn the engine clockwise
(the other direction) until the piston hits the dead stop again. Lets say it stops at
20 degrees.  Loosen the bolt holding the degree wheel and rotate the degree
wheel to 30 degrees and re-tighten the bolt.
In a perfect world zero degrees will be exactly TDC. In reality you will have to
repeat the process to fine tune things to get exactly TDC.
When you have everything just right the degree wheel will stop at exactly 30
degrees when you turn the engine in both directions

TDC       Top Dead Center
BTDC     Before Top Dead CEnter
ATDC     After Top Dead Center
BDC       Bottom Dead Center
BBDC    Before Bottom Dead Center
ABDC    After Bottom Dead Center