How To Rebuild Your Small-Block Ford.pdf - Index of

1 c.
"Reading" your spark plugs is a good way. of judging your engine's condition. Worn-out spark plugs
as in A are easily recognizable by eroded electrodes and pitted insulator. Replace them and your
engine's performance will improve instantly. Oil-coated and fouled plug B indicates internal engine
wear: piston rings, cylinder bore and valve guides. Carboned plug C coated with dry, black and fluffy
deposits is usually caused by carburetion problems or driving habits. Normal spark plug D has a
brown to greyish-tan appearance with some electrode wear indicated by slightly radiused electrode
edges. When inspecting your plugs keep track of the cylinder each belongs to. Photos courtesy
Champion Spark Plug Company.
SOLID-STATE IGNfTlON SYSTEMS .
Many solid-state (electronic) ignition
systems generate very high secondary
voltage peaks when a spark-plug lead is
unloaded by disconnecting it from its
spark plug or by disconnecting the coil-todistributor
lead while the engine is being
cranked or is running. The resulting secondary
voltage surge (up to 60,000 volts)
can damage a coil internallv or ~ krce 1
plug-wire insulation or a distributor cap
as the surge seeks a ground. So if you
remove any secondary lead with the ignition
on and the engine turning, ground
the lead to the engine with a jumper wire.
Ford has installed solid-state (breakerless)
ignitions since 1974.
Vacuum gauge being used to check the pumping
ability of this engine. The needle fluctuated
indicating a weak cylinder.
combustion engine is a specialized air
pump, so how it sucks air, or pulls a
vacuum is an indicator of its mechanical
soundness, or how your engine's cylinders
are sealing relative to one another.
You'll need a vacuum gauge and a remote
starter or a friend to operate the starter
switch while you watch the vacuum gauge.
The remote starter lets you control the
starter from under the hood.
When doing this test, connect the
vacuum gauge to the intake manifold
after you've warmed up your engine.
Disable the ignition system so the engine
can't be started. Disconnect the hightension,
or distributor-to-coil lead so the
engine won't start when it is being
cranked. With electronic systems, disconnect
the distributor-to-amplifier lead.
With your eye on the vacuum gauge,
crank the engine. If the gauge indicates a
steady vacuum reading after it has stabilized,
all eight cylinders are sealing the
same in relation to one another. If the
needle fluctuates, indicating a pulsating
vacuum, one or more of the cylinders has
a problem, assuming your starter is cranking
steady. It could be valve timing due
to incorrect adjustment, a worn camshaft
lobe or collapsed valve lifter, a leaking
valve, worn cylinder bore or piston rings
or a leaky head gasket. If this indicates
a bad cylinder/s, the next two tests pinpoint
which one it is.
Power-Balance Test-A power-balance test
determines if all of your engine's cylinders
are contributing the same amount of
power. The method is to fast-idle your
engine, then disconnect the spark plugs
one-by-one and monitor the RPM drop.
RPM change indicates how much each
cylinder is contributing to overall engine
power. The less it drops, the less it contributes.
You'll need a tachometerone
that is very accurate such as found
on a good dwell tachometer. Disconnect
the spark plug leads at the distributor and
reinstall them loosely. When removing the
leads, don't pull on the wire, pull on the
boot. With your engine warmed up and
the tach connected, start your engine and
set its idle speed to about 1,000 RPM.
Remove the cylinder 1 spark-plug lead
and ground it to the engine. Record engine-
RPM drop after it stabilizes at the lower