Small Block Cylinder Heads
heads determine the personality of an engine as much as the camshaft and
system do. Modern Ford V-8 engines have always struggled to make power using stock
components for one basic fundamental reason—port size and bowl design. One trick has been
to open up the ports with grinding and polishing to improve air flow. Another popular
performance trick has been to fit the 221, 260, 289 and 302 engines with 351W heads to
Ford looked to its own parts shelf for power when it conceived the Boss 302 engine (basically
nothing more than an old hot rodding trick), making a cylinder head swap from the 351
Cleveland engine family when it debuted for 1970. The 351C’s large-port cylinder heads
worked wonders on the 302 engine because they flowed huge quantities of air at high rpms.
Simply put, they made torque on the high end. They weren’t much for low rpm street use,
Small-block Ford cylinder head identification is straightforward and fairly easy if you know what
to look for. The most important issue to remember is casting number versus the cataloged
Ford part number. Rarely are the two ever the same. What we’re concerned with most here
are casting numbers found on the castings themselves.
The 221 cylinder head is identifiable by observing its small, kidney-shaped 45cc chambers and
1.59/1.39-inch valves. These heads are typically numbered C2OE or C3OE and are all
virtually the same. The 260 heads have slightly larger, kidney-shaped chambers at 54.5cc
chambers with the same size valves as the 221. These heads typically have three possible
casting numbers—C2OE-F, C3OE-B, or the improved C4OE-B 260 head introduced in
February of 1964, with larger 1.67/1.45-inch valves and same 54.5cc chambers.
The 221/260 heads sport
small 45cc and 54.5cc chambers respectively, which is great for
compression. Their small ports don't do much for power, however. Valve size is
1.59/1.39-inches intake/exhaust. An improved 260 head for 1964 has larger 1.67/1.45-inch
valves like the 289.
The 289 head was available in several configurations beginning first in 1963. Like the 260
head, the 289 head has 54.5cc chambers with more recessed sparkplug penetration in a high-
swirl design. What’s more, valve sizes were the same as the 260’s at 1.67/1.45-inches. The
289 head casting numbers were typically C3AE-F, C3OE-E and F and C4AE-C from 1963-64.
Casting numbers evolved to C5DE-B, C6DE-G and C6OE-M from 1965-66. C6DE-C and
C6DE-E were smog heads machined for the Thermactor air pump system on California sales
district bound vehicles beginning in the 1966 model year. Using a Thermactor head does not
adversely affect power. The Thermactor air pump manifold ports can be plugged and the head
used without the Thermactor system. If you’re building a vehicle originally equipped with
Thermactor, your cylinder heads must be a casting equipped with the Thermactor ports. Non-
Thermactor heads cannot be modified for the Thermactor manifold.
The 289 head has a slightly
larger chamber than the 221/260 at 54.5cc. The 289 head is
identified by the "289" in the casting as shown. Earlier castings for the 221 and 260 don't have
this identifying mark.
Beginning May 2, 1966 in
production, the 289 head was revised for rail-style rocker arms.
Push rod guide holes cast in the heads were eliminated with the rail-style rocker arms.
Numbers to look for are C7OE-A, C7OE-B, C7OE-C, C7OZ-B and C7ZE-B from mid-1966
From 1962 until May 2,
1966, all 221/ 260/289 engines had pushrod guides cast in the
cylinder head. Beginning May 2, 1966, Ford went to a rail-style rocker arm where the rocker is
centered at the valve. The rail-style rocker arm is on the left. The valve cover also changed
with the advent of the rail-style rocker arm. Pent-roof valve covers cleared the rail-style
For the 1968 model year,
the only part numbers to look for are C8OE-D, C8OE-L and C8OE-M
for the 289, which employ lower compression 63cc chambers for use on the 289-2V engine
that year. Despite changes in part and casting numbers, all of these 289 heads are basically
the same except for machined-in provisions for Thermactor. The main thing to watch for in
changes is valve and combustion chamber sizes. Part and casting numbers are directly tied to
The 289 High Performance cylinder head is a unique casting. The Hi-Po head has cast-in
valve spring pockets that maintain spring stability at high revs. This head also has screw-in
rocker arm studs. These features make this head very desirable for racing and street
performance applications. Valve size is the same as the standard 289 head through 1967. The
1967 289 High Performance service head has slightly larger ports while keeping the same
sized valves. The Hi-Po head number to look for is C3OE, which is the 1963 head with small
49.2cc chambers (for higher compression). This head has the smaller valves—1.67/1.45-inch.
Beginning in 1964, the 289 Hi-Po’s intake valve size increased to 1.78-inches where it
remained through 1967. Combustion chamber size increased to 54.5cc for 1964, just like the
standard 289 head. Numbers to look for here are C4OE-B, C5OE-A and C5AE-E. These
heads are obvious at a glance. Just look for the valve spring pockets and screw-in studs.
The 1963-67 289 High
Performance head is easily
identified by the double-dot
"289", valve spring pockets and
screw-in rocker arm studs. Note
the pushrod guides cast in the
head. The 289 High
Performance engine was never
fitted with rail-style rocker arms.
Despite the 289 High
Performance head’s reputation for rarity, the aftermarket cylinder head
industry has taken the spotlight off of the Hi-Po head. Cost considerations and a better design
in the aftermarket have made the 289 High Performance head less desirable when
performance is the only goal. Engine Factory provides almost all of it's engines with Aluminum Cylinder Heads.
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