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

VALVE JOBS AND HIGH-MILEAGE
ENGINES
Doing a valve job only on a relatively
high-mileage engine may not solve its oilconsumption
problem. The reason is, as
an engine wears, its parts wear together.
As the sealing quality of the valves becomes
less, the same thing is happening to
the rings and pistons. After the cylinder
heads are reconditioned, they will seal
better, creating higher compression and
vacuum loads on the rings and pistons.
Where the rings and pistons were doing a
satisfactory job before, rhey may not be
able to seal adequately after a valve job.
Increased oil consumption and blowby
result. So beware of the valve-job-only
solution.
and record the figure. Now, bump the
engine over until the pushrod is loose, indicating
the valve is closed, and remeasure.
You can read valve opening directly with
the indicator. Repeat this a couple of
times to make sure of your figures if there
appears to be a problem with the valve
sticking or a worn cam lobe. You should
arrive at a valve-lift of 0.368-0.477 inch
depending on which engine you have. Refer
to the specification on the preceding
page for the correct valve lift.
One problem with checking the valve
lift on high-mileage hydraulic-lifter engines
is the lifters are usually so worn that they
can't maintain sufficient pressure to hold
the valve completely open. They leak
down and partially close the valve even
though the lifter is on the toe of the cam
lobe. Be aware of this problem if your
engine fits this category.
What if a valve lift is not up to specification
You are checking for a sticking
valve, so this is the first thing to suspect.
As a double check, the installed height of
the valve spring when the valve is closed
should measure 1.50-1.80 inches. This
measurement is made between the spring
pad and the underside of the spring retainer.
Check the specification chart for
your engine. If it is less than specified,
the valve is sticking or being held open by
something. As a final check, back off the
rocker-arm adjusting nut until the rocker
arm is loose. This will confirm a sticking
valve if spring height doesn't change. You
can remove the head with some assurance
that a valve job is in order. If the spring
or valve lift does come up to specification,
recheck cylinder pressure, but only after
adjusting the valve and warming up the
engine. If it comes up to pressure, you've
found the source of the trouble, at least
with this cylinder.
Checking Camshaft Lobe Wear-If you've
found a valve is not lifting to specification,
but it's properly adjusted and the
installed spring height is right, a worn
cam lobe has nothing to do with causing
low cylinder pressure, but it has a lot to
The number of years the small-block Ford has been around, plus the changes it has
undergone during these years makes it impossible for any one person to write a
book such as this. Completeness and accuracy required that I get help from people
who make their living selling or manufacturing engine parts, rebuilding engines and
servicing them.
At the risk of leaving someone out, 1 am grateful to: Denny Wyckoff who was
always ready to share his years of engine rebuidling experience, and answer one
question after another. Daryl Koeppel and his sidekick Jim Hambacher of Holmes
Tuttle Ford always took time to answer questions concerning parts, part numbers,
interchangeability and those troublesome change levels. They also furnished parts
for many of the photos you see throughout the book.
Don Wood and Sam Ellison provided words of wisdom about removing and
installing engines. Charlie Camp, drawing on his years of experience as. a Ford
Service Engineer, was invaluable as he checked the accuracy of my manuscript and
made many helpful suggestions. Bill Wheatley and Jeff Quick also took time out of
their busy schedules to read over the manuscript and offer suggestions.
All of the photos and drawings credited to Ford Motor Company were cheerfully
supplied by Linda Lee of Ford's Parts and Services Division. Others I would like to
thank are: Ed Kerchen of Associated Spring, Bob Bub of Cloyes Gear and Products,
Bob Lopez of Federal Mogul, Tom Tlusty of Muscle Parts, Cal DeBruin of Sealed
Power Corporation, Jack Little of Sun Electric, Terry Davis and Gregg Strugalski of
TRW, Dale Cubic of Mr. Gasket, Randy Gillis of Sig Erson Racing Cams, Bill
Borrusch and Bob Robertson.
do with engine power loss.
If your engine is down on power,check
all of the valves with the dial indicator.
Rather than using the spring retainers to
check from, a more accurate method is to
check each cam lobe directly via its pushrod.
You'll have to loosen all the rockerarm
adjusting nuts and rotate the rockers
out of the way of the pushrods. Starting
with the number-1 cylinder, mount the
dial indicator so it is lined up with the
center of the pushrod. You may need a
piece of tape around the dial-indicator
plunger and pushrod to prevent the pushrod
from falling away from the plunger.
Make sure the pushrod is well seated in
its lifter and the lifter is solidly against
the base circle of the camshaft lobe. With
the dial indicator set at zero, slowly bump
the engine over with the starter while you
watch the indicator, Note the maximum
indicated reading and record it with the
cylinder number and whether it is an intake
or exhaust valve. You'll need this
information later for comparison to the
other lobes.
Camshaft lobe lift is the difference between
the highest portion of the lobe and
the diameter of the base circle as indicated
by the sketch on page 64. Lifts vary
from a high of 0.2983 inch to a low of
0.2303 inch, depending on which engine
you have. Refer to the specification chart
on page 9 for this information.
When checking camshaft lobe wear,
you won't have much trouble distinguishing
the bad ones from the good ones. When
a lobe starts to wear, it goes quickly. It
doesn't wear gradually like a cylinder
bore. Differences won't be in thousandths,
they'll be in tenths of an inch. All the
lobes of a camshaft don't all wear down
at once, they go one at a time. It's not
uncommon to see only one lobe of a cam
wear while the rest are perfectly all right.
Regardless of how many lobes you find
worn, if You find any, replace the cam
and all lifters. Otherwise, the new cam
will be ruined before YOU get out of your
driveway. Use the procedure outlined in
the engine assembly chapter when changing
a camshaft and lifters.
One final note before proceeding to
the next chapter, if you've discovered a
bad caln, but Your engine's com~ression
is good and it doesn't use much oil-no
more than one quart Per 2000 miles, I
suggest that You install a new camshaft
and lifters. However, if your engine is Up
to 500 miles Per quart and the COmPressi0n
On a few cylinders is less than 75 percent
of the highest, it is time to rebuild.
1 FIRING ORDER
Making assumptions can get you into
trouble when it comes to diagnosing, tuning
or building an engine. One of the most
common assumptions made when it
comes to the Ford small blocks is that
their firing orders are all the same. Not
so, the 351 W fires differently: 1-3-7-2-6-
5-4-8. The 221 through 302 fires: 1-54-2-
6-3-7-8. Firing orders are cast into the top
of the intake manifolds.