Tecumseh ECV105 Technician's Handbook page 73

Begin the procedure by replacing the points if necessary.
To do this remove the nut that secure the movable portion
of the breaker points. Remove the screw from the
stationary portion of the breaker points and the worn
breaker point assembly. Install a new breaker point
assembly and adjust the point gap. This is done by rotating
the crankshaft until the point arm is resting on the high
side of the ignition cam. Set the point gap by loosening
the screw on the movable point set and insert a feeler
gauge per specification. Adjust the point gap so that a
light drag is felt on the feeler gauge. Tighten the screw
and recheck the gap. Leave the leads unattached for the
timing procedure. Use this procedure on all standard point
ignition systems when point replacement is necessary
(diag. 21).
Install a dial indicator (Part # 670241), equipped with the
correct tip on the extender leg. Use the small tip for
engines with timing dimensions of between top dead
center (T.D.C.) and .050" (1.27 mm) before top dead
center (B.T.D.C.). Use the large tip for engines with timing
dimensions of between .051" (1.295 mm) B.T.D.C. to
.150" (3.81 mm) B.T.D.C. Make sure to secure the
extender leg in position to locate the tip directly over the
piston head. Loosen the screw on the side of the adaptor
sleeve to allow the sleeve to be turned into the threads of
the spark plug hole, not the entire dial indicator. This will
ensure the proper location of the tip. Once the adapter
sleeve is secured in the hole, tighten screw on sleeve
adaptor to prevent the dial from moving up or down, which
would give a false reading (diag. 22).
Find T.D.C. with both valves closed by rotating the
crankshaft clockwise when looking at the magneto end
of the crank, until the needle on the dial stops and
reverses direction. Where the needle stops is T.D.C.
Loosen the screw on the dial, and rotate the dial so that
zero is lined up with the needle at T.D.C. Tighten the screw
on the dial to secure it in place (diag. 23).
While watching the needle on the dial indicator, rotate
the crankshaft counterclockwise when looking at the
magneto end of the crank, .010" (.254 mm) past the
B.T.D.C. dimension. Then rotate the crankshaft clockwise
to the proper B.T.D.C. dimension, this will take out any
slack between the connecting rod and crankshaft
assembly.
Example: If the specification of .080" (2.032 mm) is the
B.T.D.C. dimension, rotate the crankshaft counter-
clockwise so that the needle on the dial indicator travels
to .090" (2.286 mm) B.T.D.C. (diag. 24), then rotate the
crankshaft clockwise so that the needle travels to the
specified dimension of .080" (2.032 mm) B.T.D.C. (diag.
25).
Next, if the original breaker points are being used,
disconnect the leads from the point terminal. Reinstall
the nut & tighten. Connect one lead of a continuity light,
or ohmmeter to the point terminal and the other lead to a
good ground. Loosen the two bolts holding down the stator
and rotate the stator until the continuity light or ohmmeter
indicates a break in the circuit. Torque down the stator
bolts while maintaining the stator plate position and the
timing procedure is completed. Reconnect the leads on
the point terminal and tighten the nut making sure that
the leads do not touch the flywheel (diag. 26).
CRANKSHAFT
DIAL AT
.090"
(2.286 mm)
(continued on top of next page)
ARM
PIVOT
SLEEVE
DIAL AT 0"
DIAL AT
.080"
(2.032 mm)
24
IGNITION
CAM
POINTS
21
DIAL SCREW
SLEEVE
SCREW
22
23
25
26
69