Jim Smart
May 1, 2005
Photos By: Chris Richardson

What If Your Hi-Po Block Is Toast?

What happens if you're restoring a K-code Mustang and have a block that's .040-inch over or damaged from engine failure? You have two options: have the block sleeved at approximately $100 a cylinder or search for a C4OE or C5AE block casting with a standard bore (challenging to find today) and transfer your Hi-Po main caps to the fresh block. To use the Hi-Po main caps on the fresh block, have the block and caps line-bored and honed for a perfect match. Mexican Ford blocks also have the wider Hi-Po-style main caps if you need wider main caps. Mexican blocks can be identified by an M in the fourth position in the casting number.

Because 289 High Performance blocks were stamped with the vehicle serial number, you'll need to stamp this number into the replacement block using the same type Ford used.

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Ignition System

Because the 289 Hi-Po is a high-revving engine, good coil saturation and a reliable spark were required. This is why the Hi-Po was equipped from the factory with a dual-point ignition. Not only does the Hi-Po distributor have dual breaker points, they aren't the same points found in single-point distributors. They're Autolite dual-point specific, with stiffer breaker arms for smoother operation at high revs. What makes the Autolite dual-point even more unique is the absence of a vacuum advance unit. Only a centrifugal advance is involved, which comes on as engine revs increase.

Six Hi-Po distributor part numbers were involved from 1963 to 1967: C3OF-D, C3OF-F, C4ZF-D, C5OF-E, C7ZF-J, and C7OF-K. All employ the same basic advance curve and breaker dwell settings. Ford opted for cooler-heat-range spark plugs for the Hi-Po. Where the 289-2V/4V had the Autolite BF42, the Hi-Po had BF-32s.


The 289-4V engines were fitted with a 480-cfm 4100 carburetor with an automatic choke; the Hi-Po got a 600-cfm carburetor with a manual choke. Carburetor identification is simple: just look at the bore sizing and the carburetor tag (if equipped). The 480-cfm Autolite 4100 has 1.08 venturis and 171/416-inch bores. The larger 600-cfm 4100 has 1.12-inch venturis with 191/416-inch bores. What makes the Hi-Po's 600-cfm 4100 unique is the absence of a hot-idle compensator and an automatic choke. These items were common with big-block applications.

There are eight different Ford part numbers for 289 Hi-Po carburetors. Five were for manual transmissions (no kick-down linkage). Two were for automatic-transmission applications. They became more specific mostly in jet sizing, which hinged on where they were delivered new. High-elevation deliveries received different jetting than low-elevation.


The 289 Hi-Po alternator ('65-'67) and generator ('6411/42 only) have a larger drive pulley to keep the revs down at high revs. This keeps the alternator/generator windings from exploding at high revs. Art Cairo's unusual '6411/42 hardtop, which was used for our photography, was fitted with an early Lincoln-style Autolite 35-amp alternator, which is likely the only '6411/42 ever assembled with an alternator charging system.

Exhaust Manifolds

Another obvious difference with the 289 Hi-Po is the factory cast-iron exhaust headers. Designed to improve exhaust scavenging, much like the late-model 5.0L High Output Mustangs did with shorty tubular headers, the cast-iron headers don't claim to work as well as long-tube aftermarket headers. But, it's better than the standard 289-2V/4V log-style exhaust manifolds. The part numbers are C3OE-9431-B (driver side, '64-'65), C4ZE-9430-A (passenger side, '64-'65), C7ZE-9431-A (driver side, '67 only), and C7ZE-9430-A (passenger side, '67 only).