Diagnosis Group; The Tune-Up Diagnosis Tests; Compression - Pontiac 1953 Owners Service Manual

3. Lubricate distributor rotor wick, cam, breaker-point pivot, breaker
plate felt.
4. Lubricate carburetor pump arm (on 8 cylinder cars only).
5. Clean fuel pump sediment bowl.
6. Clean and re-oil carburetor air cleaner and oil filler and venti·
lator cap.
NOTE: When heavy duty oil bath air cleaner and ventilator equip.
ment is used, ventilator outlet should also be cleaned.
DIAGNOSIS GROUP
1. Tests and checks on the engine as shown on the sample Tune-Up
Diagnosis Sheet reproduced on page 44.
By purchasing the complete tune-up diagnosis rather than having
the individual operations performed at separate times, a saving is
achieved by eliminating over-lapping or duplicating operations.
Then you only pay for having each operation performed once-and
in the most efficient order.
The Tune-Up Diagnosis checks and tests eliminate "guesswork"
errors in diagnosis. These tests also help avoid starting difficulty in
cold weather or trouble on the road by finding indications of impend-
ing trouble before it occurs.
If at all possible, we recommend that you
stay and watch as the
service man makes these tests.
THE TUNE-UP DIAGNOSIS TESTS-The
Tune-Up Diagnosis
tests are performed as shown on the test sheet reproduced on page
44. While this test sheet may look complicated, with such items as
Vacuum Reading, Cylinder Balance, Starting Motor Amperage
Draw, and Distributor Resistance, the tests are actually very simple.
In order to understand some of the tests and checks, they have been
divided into three fundamental sections-compression, ignition, and
carburetion, each having an individual function in the operation
of the engine. We will explain briefly the three sections and how
they must work together to give you a good operating engine.
COMPRESSION-Compression in your motor
is the squeezing of the air-fuel mixture in the
cylinder. If you drove cars
in the days when
hand cranking was common, you'll remember
that the newer the engine was, the higher the
compression/ or the harder it was to "turn-over".
Keeping compression at its maximum and
equalized in all cylinders insures smooth power-
ful operation. The tests in the compression section
check the compression in each cylinder and tell
you the condition of the piston rings a nd valves.
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