Precision Turbo and Engine BigStuff3 GEN3 Powertrain Controller Ignition Setup Tutorial - Manual (Page 21)

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other than this number, then there is a synchronization problem between the cam and crank. The cam
sensor may need to be moved to correct the cam sync problem.
“Specific Details”
Measuring Distances on the Surface of a Dampener.
The following formula can be used to measure the distance on the radial face of the balancer. In this
example, 10
o
BTDC is being calculated.
Accurately measure the diameter of the dampener, then multiply the diameter by 3.14. Divide the
result by 360, and then multiply by 30 (representing the 10
o
).
Example based on a 7” balancer: 7 x 3.14= 21.98. 21.98/360= .06105” (per degree). .06105” x 10
o
=.6105”. From the TDC mark on the balancer, measure forward (clockwise) about 5/8” and make a
mark, this will represent 10
o
BTDC.
“Do it Right” Find TDC
All the ignitions setups outlined in this tutorial assume the Top Dead Center (TDC) position on the
dampener equals true TDC for cylinder number 1, compression stroke. This assumption could be
robbing you of power or worse, so the best approach is to verify TDC and you’ll be assured to get the
most of your engine.
Finding TDC
TDC is the point at which the piston in cylinder #1 reaches its uppermost position in the cylinder.
Ignition timing is usually expressed as degrees before top dead center (BTDC) or after top dead center
(ATDC). A timing mark on the crankshaft dampener corresponds to the top dead center position of the
number one cylinder, compression stroke. It is important that TDC is verified. A simple process for
verifying TDC for number one (1) cylinder (compression) is outlined in the paragraphs below.
Finding TDC when the cylinder heads are on the engine
One way to find Top Dead Center (TDC) is to use a piston stop and a degree wheel. Make sure that
the piston is down in the cylinder and then thread the piston stop into the #1 spark plug hole.
Note: If your engine does not have a rigid pointer already mounted near the dampener, now is the best
time to fabricate a permanent pointer. A permanent pointer will need to be fabricated for this
procedure and to be able to continue to verify the timing in the future. A crankshaft degree wheel, or a
balancer with timing marks on it, or a timing tape is required for this procedure.
Using a Degree Wheel
Securely fasten the degree wheel to the front of the crankshaft. Next, fabricate a rigid pointer to point
at the front of the degree wheel (even though you may have a permanent pointer since the degree
wheel diameter may be larger than the dampener).