cooling system until it’s too late.
But the cooling system is one of
the first areas that needs to be
considered because it is an
engine’s life insurance policy.
Ford engines have always
struggled with cooling problems
due mostly to factory radiators
that weren’t large enough for the
task. Small-blocks struggle most
because they’re installed in
compacts and intermediates
which don’t have enough
radiator, or air flow, due to
limited grille size. Small-block-
equipped Mustangs, Falcons,
Fairlanes and Comets suffer the
most due to their tiny radiators.
In the years since these cars were rolling off Ford assembly lines, the aftermarket has solved
many of the cooling problems by adding rows of cooling tubes to the radiators. Early
Mustangs, Falcons, Fairlanes and Comets were cursed with small radiators which were limited
in cooling capacity, and they liked to split at their top tank seams, spraying coolant all over the
engine compartment. Reproduction radiators available today offer identical-to-original
construction coupled with better quality and improved cooling capacity. There are also a
wealth of aftermarket aluminum and brass radiators designed for the demands of motorsports
and severe-duty applications. Based on what is available today, no Ford small-block should
ever suffer an overheat.
For 1966-67 and newer Ford compacts and intermediates, there is the higher capacity radiator
for air-conditioned Fords and Mercurys which offers better design and higher cooling capacity.
We see this radiator most often on air-conditioned Mustangs, Cougars, Fairlanes, Torinos,
Comets and Cyclones.
you to choose the right radiator for the job. The key to properly matching radiator and
transmission is to reach for the highest capacity possible, paying close attention to inlet and
outlet positions, and the use of automatic transmission cooler connections, if necessary, for
your application. Another important issue to keep in mind is radiator height. Mustangs and
Cougars through 1970, for example, have a lower hoodline, which means radiators that are 1-
inch shorter than those for full- and intermediate-size car lines. Opt for a 17-inch tall radiator
for a 1965-70 Mustang/ Cougar and your hood will not close. When reaching for cooling
capacity, look at width and thickness, taking care not to choose a radiator that’s too wide for
the radiator support. Also keep in mind cross-flow versus vertical flow in your search.
Choosing the right water pump for your small-block Ford doesn’t have to be a daunting task.
There’s no magic here. A handful of basic types were used. All Ford small-blocks, except the
289 High Performance, prior to 1966, were equipped with aluminum water pumps (C5AZ-8501-
K) from the factory. As a result, they were equipped with a timing chain cover specific to the
aluminum water pump (C4AZ-6019-B). This timing cover is not compatible with the cast iron
water pumps.
Whenever you’re building a small-block Ford, we advise against the use of the pre-1966
aluminum water pump unless you’re striving for originality. Instead, upgrade to the cast iron
water pump (D3UZ-8501-A or C5AZ-8501-A). The important thing to remember is the
difference between the D3UZ and C5AZ cast iron pumps. The D3UZ pump is the standard cast
iron water pump used on 289, 302 and 351W engines through 1969. The C5AZ high-flow
pump was originally 289 High Performance-specific from 1965-67. These water pumps are
interchangeable, with their inlets located on the right-hand side of the vehicle. To upgrade to a
cast iron water pump, you must use the appropriate timing chain cover (C4AZ-6019-B) or any
post-1965 timing cover compatible with the cast iron water pumps.
cast iron water
pump common to
289/302/351W
engines.
and have lost their original identity, casting numbers don’t have the validity they used to.
Fortunately, the aftermarket offers a wealth of high performance water pumps for Ford small-
blocks.
Small-block cast iron water pumps remained much the same through 1969, with a right-hand
inlet for the lower radiator hose. Beginning in 1970, 302 and 351W small-block Fords received
a new water pump casting (D0AZ-8501-C) with the inlet on the left-hand side of the engine.
Boss 302s for 1969 were fitted with a 1969-specific high-flow water pump (C9ZZ-8501-A). A
year later in 1970, the Boss 302 engine was fitted with the D0ZZ-8501-B water pump.
position changed to the left-hand
side of small-block Fords. This
was timed with the move to a
four-bolt harmonic balancer. If
you see the four-bolt balancer,
you should see a left-hand
coolant inlet.
left-hand inlet, just like Boss 302, 302 and 351W engines from 1970 and up. The only real
difference in these water pumps is flow rate. They are virtually interchangeable otherwise.