24 MUSTANGMONTHLY.COM
INSIDE THE BOSS 429 WITH GERALD BILLUPS
are used to seal the tops
of the cylinders and the
water and oil passages
between the heads and
the block in this dry-deck
method of engine assembly.
Installing the O-rings will
try the patience of the most
experienced engine man.
There’s a lot of room for
error during installation,
and leaks abound if they’re
not properly seated. Yet
Gerald happily takes
whatever Boss 429 engine
his sons throw at him and
makes them run as fast and
hard as Ford originally built
them. “It runs like a bat out
of hell,” Baer says. “It’s a
really good car.”
It’s not just the
performance that sold Baer
on his latest Boss 429; he’s
also found himself taken
with its mossy green color.
“I didn’t like the color at
first when I saw it on them
years ago, but now it’s one
of my favorite colors,” Baer
says. “A lot of the [Black
Jade] cars I have seen over
the last 20-25 years, they
were just real old-looking,
but after seeing the color
right after it was done, it
kicks ass.” The jury is in,
and it’s not just Baer who
thinks Black Jade is one
“boss” color.
“I personally like the
color,” says Jason Billups.
“It’s probably not my
favorite color—the black
Boss ’9s are my favorite—
but it’s probably my second
favorite color. You don’t
see a lot of the Black Jade
cars restored correctly, and
when you see [the color]
done well, it really pops.”
He’s not alone. Black Jade
seems to appeal to a fairer
demographic as well. “I
don’t know what it is, but
women seem to love that
color,” he says. “They say,
‘It’s my favorite color.’”
THE MISSING LINK{BOSS 429}
G
erald Billups’ experience with
engines goes back decades,
and ever since his sons opened
Billups Classic Cars, he’s gotten
serious about them in a professional manner.
He opened his own engine shop and has had
enough Boss 429 engines (about a dozen) go
through his doors that he can tell you all the
differences between the early S-series Boss
engines, the later T-series Boss 429 engines,
and even the prototype Boss 429s, right down
to the weight differences of the rods. Baer’s
car further complicates matters because it
was built around the time of the changeover.
“It’s a really early T-series motor because
it is KK1615, so it’s a T-motor car, but it still
had the magnesium valve covers, which is
what they originally used on the S motor,”
Billups says. He noted the change from magne-
sium valve covers happened around KK1700.
According to Gerald, the internal differ-
ences between the early S-series Boss 429
engine and the later T-series relates to the
crankshaft, rods, and pistons. “Les’ motor is
a T motor. The T motors have a C9AE-B rod,
and that’s basically the same rod as a 460/429
Cobra Jet. It’s a little bit heavier rod. The
T-series rod is also longer. Even the wristpin
is a different size (than the S-series). On the
S motors, the rod number is C9AE-A. That
rod is shorter and lighter. They use ½-inch
bolts and a smaller pin. To center those
rods up, they have two dowels in the rods
to center the cap.”
The part numbers for the rods, pistons,
and cranks for S-series Boss 429 blocks have
an “A” suffix, while the T-series parts have a
“B” suffix. And while rods and cranks can be
intermingled, pistons and rods can’t, Billups
says, because of balancing the different
weights and lengths of the rods, the different
weight of the pistons, and the dowels used in
the S-series rods.
Although it’s not necessary, a rebuilt
S-series engine will ideally retain the S-series
C9AE6300-A forged-steel crank and the
T-series engine will use the C9AE6300-B
crank. This is in spite of the fact that only the
S-series crank has a spacer on the front.Q“It’s a really early
T-series motor because
it is KK1615, so it’s a
T-motor car, but it still
had the magnesium
valve covers, which
is what they originally
used on the S motor,”
Billups says. QThe engine after the Billups team rebuilt and restored it.The elder Billups adds that the Boss 429
engine is a good, solid performance engine,
but it does have one weakness that often led
them to be retired after 20,000 to 30,000
miles. He says, “I like the Boss 429 engine
block. It’s a good block—they really are. But
the Boss ’9 had a forged crank and they are
cross-drilled and I don’t like that. They blew
up a lot of those motors back in the day. I have
done very few of them that weren’t blown up
at some point.”
He continues, “In a cross-drilled crank,
they [oil galleries] are open and the oil can
just go wherever it wants to go. It’s like water.
Water takes a path of least resistance, and in
someplace, it’s going to starve. A starved bear-
ing is going to get burned out.”
Ideally in a performance engine, Billups
says oil should be fed directly to each main
bearing and rod. “When you are spinning an
engine up tight, it’s important to properly
oil the bearing and rod,” he says. “If you are
not putting a lot of rpms on them, it’s not a
big deal. But when you start making a lot of
rpms, it is.”
After miles of hard use, Billups said a lot
of Boss ’9 engines threw rods or spun bear-
ings and ended up with sleeves in the block.
Despite its relatively high mileage of 60,000,
the 429 in Baer’s Black Jade Boss 429 skated
by without a sleeve. Even though it was seized
when it arrived at Billups Classic Cars, the
engine made for a great builder. Today, it runs
as good or better than new.QThe Boss 429 engine as found.