56
manuals for the detailed position); or the negative pole of the ignition coil if the automobile is
equipped with a distributor board (Refer to the appropriate service manuals for the detailed position).
(4)
The normal starting rotation speed of an engine is about 50 RPM to 275 RPM. Refer the
detailed position to the servicing handbooks of various kinds of automotive manuals because this
value relates to the then temperature, engine size, battery size, etc..
Warning:
The displayed value of the meter becomes the actual tach reading only after it is
multiplied by 10.
Fuel System Testing
It is necessary to add more accurate engine fuel control to a low injection automobile. Since 1980,
the automotive manufacturing industry has used electronically-controlled carburetor and fuel injection
so as to achieve lower fuel injection.
(1)
GM (General Motor):
Testing the dwell of the C-3 mixed-control solenoid: Place the solenoid
in a cylinder, monitoring the ratio between the air and the fuel, which should generally be 14.7 to 1
between the air and the fuel so as to reduce the injection of surplus fuel. The testing is used to see if
the solenoid is installed right in the position and the dwell of the meter can also indirectly used for the
testing.
[1]
Start the engine of the automobile to achieve a rotation speed of 3000 RPM.
So far as a GM automobile is concerned,set the rotary switch to the
DWELL
and select
6CYL
.
72-9280: OPERATING MANUAL
