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VACUUM TEST
An engine in good :condition - will show a
steady, or slight fluctuating , high vacuum
reading from 18" to 21". Vacuum readings
are affected by altitude. Over 2000 feet the
vacuum gauge will show about one inch lower
for each 1000 feet of elevation.
1. Remove wiper hose at intake manifold and
connect vacuum gauge hose. (If the engine
has
a
combination
pump,disconnect the booster pump line at intake
manifold.)
2. Check carburetor and intake manifold nuts
for tightness.
3. Connect one lead of tachometer to the distributor
primary terminal and the other lead to engine for
ground. Adjust carburetor to obtain a smooth idle
at 540 to 580 R.P.M. If car is equipped with
Hydra-Matic Transmission, set idle speed at 490-
510. Vacuum readings at sea level may be inter-
preted generally as follows:
18 - 21" Steady or with slight fluctuation: En-
gine in good condition.
15"
Steady: Incorrect ignition timing.
10"
Steady: Incorrect valve timing, or
burned valves.
15 - 21" Fluctuating: Sticking valves or com-
pression leak.
12 - 16" Drifting: Carburetor too rich or too
lean
.
Any number of engine conditions may
cause the same action of the vacuum gauge.
The exact cause must be established by process
of elimination.
VALVE TAPPETS
Check the valve tappets clearance when
the engine is at normal operating temperature.
Correct valve clearances are .010" for
intake valves, .012" for exhaust valves.
fuel
and
vacuum
ENGINE TUNE-UP 10
TAPPET ADJUSTMENT
1. Raise front of car, place stand jack under
frame cross member and remove right front
wheel.
2. Remove bolts on the fender side dust shield
and attaching parts and take out shield from
under the fender.
3. Remove front and rear tappet covers and
breather pipe . Take out the rear tappet cover
by sliding cover forward and out.
4. Adjust tappets and re-install parts.
CYLINDER BALANCE TEST
The Cylinder Balance Tester compares the eve-
ness of the power output of each cylinder in the
engine.
1. Connect the vacuum gauge in Figure 2 and
set the throttle until engine is running at
1500 R.P.M.
FIGURE 2
2. Ground the master clip of the cylinder balance
tester and connect individual leads to the spark
plugs 2-3-4 and 5. Engine will now run on 1 and 6.
3. Note the reading on the vacuum gauge. Make
the same test on each pair of cylinders in the
following sequence. 6 Cylinders 1-6, 2-5, 3-4.
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