Jim Smart
May 1, 2005
Photos By: Chris Richardson

For 43 years, the 289 High Performance small-block has been more myth than fact. It probably gets more credit with enthusiasts than it deserves due to rarity more than anything. What makes it "high-performance" isn't unusual or rare. What Ford did to the 289 isn't any more out of the ordinary than good, old-fashioned, hot-rodding trickery.

The 289 High Performance is a warmed-up 289 with a hotter solid-lifter camshaft, cylinder heads and a dual-point ignition designed for higher revs, cast-iron header exhaust manifolds, and a wider harmonic balancer.

So what's the big deal? Not much, unless you're restoring a K-engine-code '65-'67 Mustang or are interested in building an authentic 289 Hi-Po small-block for your non-K-code Mustang. What makes the Hi-Po a big deal is authenticity when building a K-code Mustang with the real thing between the shock towers.

We're going to teach you the basics of the 289 High Performance with quick facts you can use in your engine building and Mustang spotting. Based on what we know about the Hi-Po, you can build a homegrown Hi-Po engine without spending a fortune in elusive castings and pieces. You can achieve the clatter of 16 mechanical tappets and the throaty tailpipe sound with the right camshaft and exhaust tuning. And, you can generate more horsepower and torque without suffering with driveability issues.

The Block

Although the 289 High Performance block has a unique part number, it was not a unique block. The only difference was its wider main bearing caps. According to the 289 High Performance Mustang book by Tony Gregory, the 289 2V and 4V engines have 151/416-inch main caps that taper to 51/48 inch at the top. The Hi-Po caps are 151/416 inch from top to bottom.

Part Number Description
C3OE-6015-B Five-Bolt bellhousing
C4OE-6015-B Five-Bolt bellhousing
C4OE-6015-C Five-Bolt bellhousing
C4OE-6015-F Five-Bolt bellhousing
C5AE-6015-A Six-Bolt bellhousing
(Aug. 1964-up)
C5AE-6015-E Six-Bolt bellhousing

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Some, but not all, early 289 High Performance blocks had screw-in oil gallery plugs. Despite urban legend, 289 High Performance blocks never had screw-in freeze plugs either. Those were reserved for the '69-'70 Boss 302 blocks only.

Factory-installed 289 High Performance engines had the vehicle serial number stamped into the righthand side of the block near the battery's negative-cable attachment point.

Bottom End

Here again is where fact blows fiction right out of the water. Ford never built a production 289 High Performance V-8 with a steel crankshaft. The Hi-Po has the same 1M cast-iron crankshaft as the 289-2V/4V engine. However, Hi-Po cranks were handpicked and Brinnel-tested for strength.

The 289 High Performance was fitted with the same basic C3AE connecting-rod forgings as the 2V/4V engines. Where they differ is the larger 31/48-inch bolts, compared to 51/416-inch bolts in the standard engines. This is a cool modification you can do on any 289 or 302 connecting rod to improve strength. The downside is, there is less steel around the 31/48-inch bolts, which weakens the rod to some degree. The best compromise is 51/416-inch ARP bolts, which are stronger and don't affect rod strength.

Production 289 High Performance engines were fitted with cast pistons that were good for 6,000 rpm. Forty years ago, forged pistons weren't all that common, and they certainly weren't conventional in production engines due to cost and technology. At the time, forged pistons were available from the aftermarket.

Although most of the Hi-Po bottom end is shared with the 2V/4V engines, two items aren't: the harmonic balancer and slide-on counterweight. They're there for an important purpose: balance. The 289 Hi-Po has 3/8-inch connecting-rod bolts, which adds weight to the reciprocating mass (piston and rod assembly). This called for a wider harmonic balancer and the added counterweighting from the slide-on counterweight.


The 289 High Performance V-8's personality comes from an aggressive mechanical flat-tappet camshaft that does its best work at high revs. Peak horsepower and torque come in around 6,000 rpm. For a flat-tappet camshaft you can use on the street, the C3OZ-6250-C factory bumpstick is aggressive, with .460/.460-inch valve lift and 310/310-degrees of duration. Lift at the lobe is .298/.298 inch. Raw torque and horsepower come on strong in the high revs.

Fuel Pump

All small-block Fords of the period were fitted with Carter fuel pumps. From 1964 to 1965, it was a screw-together Carter pump with the fuel filter. From 1966 to 1967, Ford used a sealed Carter pump without the filter canister. The Hi-Po engine differs in volume: It delivers more fuel than its 2V/4V counterparts.

Clutch & Flywheel

As you might expect, the Hi-Po employed more heavy-duty driveline components. Manual transmission applications had two basic types of Borg & Beck, three-finger clutches that measured 10.4 inches in diameter. Much of it had to do with spring pressure. Because early Hi-Pos struggled with clutch slippage under hard acceleration, Ford went to a stiffer clutch for 1967.

Classic Mustangs have always suffered with clutch-release bearing and linkage woes because the old-fashioned three-finger clutch yields great pressure on the release bearing and linkage. No matter what you do with the bellcrank clutch linkage, it will not stand up well to Borg & Beck clutch stress. You can count on failure at some point in clutch service life.

Today, the Hi-Po solution is the installation of a Centerforce Dual-Friction clutch and flywheel package to improve driveability and performance. The Centerforce clutch offers light clutch-pedal effort because it's a diaphragm-style. It gets even better with the flyweights on the diaphragm fingers. As engine revs increase, the flyweights place more pressure on the fingers and disc, eliminating slippage. This is a terrific design that offers the best of all worlds.

Cylinder Heads

Our greatest fascination with the 289 Hi-Po is likely its unique cylinder heads. Urban legend has always given the Hi-Po head larger ports and valves than other small-block Fords, which has never been true. Valvespring pockets for stability and screw-in rocker-arm studs for dependability make the Hi-Po head unique, because the more common press-in studs tend to pull out with aggressive camshafts and high revs. Outside of these factory modifications, the Hi-Po heads are virtually the same as the 2V/4V heads. Spotting a 19, 20, or 21 cavity number in the corners of the castings outside of the valve-cover areas on the exhaust side quickly identifies Hi-Po heads.

Enter text here.These heads were fitted with stiffer valvesprings for obvious reasons: to reliably slap the valves closed at high revs. Spring pressure was approximately 350 pounds on the Hi-Po heads. Smaller damper springs were also used.

Look for casting numbers C3OE, C4OE-B, C5OE-A, C5AE-E, C7ZE (service head), and C8ZE-B (also a service head). The C8ZE-B service head does not have the two-digit cavity number mentioned earlier.

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).

Hi-Po Myths

Ever since the 289 High Performance V-8 was introduced in the '63 Fairlane, urban legend has abounded with this engine. Let's look at those myths and set the record straight.

Myth 1: The 289 High Performance V-8 has forged pistons.
False: From the factory, the 289 Hi-Po had the same C3OZ-6108-L cast flat-top pistons found in the 225-horse 289-4V engine. Performance improvement kits were available from Ford and the aftermarket with better pistons.

Myth 2: It has special connecting rods.
False: It has the same C3AE forging as the 289-2V/4V engines. However, this forging in the Hi-Po is fitted with larger 31/48-inch rod bolts, not 51/416-inch bolts found in the 289-2V/4V engines. The rod is machined to make way for the larger bolt head and shank.

Myth 3: It has a dual-roller timing set.
False: It has a standard timing set that's narrower than the timing set in stock 289-2V/4V engines. It's narrower to make way for the slide-on counterweight that goes on the crank first.

Myth 4: It has larger valves and ports.
False: The 289 High Performance head has exactly the same size valves and ports as the 289-2V/4V head castings. Not even the '67 service head, once rumored to have larger ports, is any different.

Myth 5: It has a special intake manifold.
False: Hate to burst your bubble, but the Hi-Po has the same 4V intake manifold as the 225-horse 289-4V engine.

Myth 6: It has a steel crankshaft.
False: Not a single 289 High Performance V-8 was ever equipped from the factory with a steel crankshaft. The only Ford small-block ever factory-fitted with a steel crank was the '69-'70 Boss 302. The Hi-Po has a 1M cast crank just like the 2V/4V engines.

Myth 7: The 289 Hi-Po has a deeper, high-capacity oil pan.
False: It's the same steel five-quart pan as the 289-2V/4V.

Myth 8: Some 289 High Performance V-8s were fitted with factory air conditioning.
False: The 289 High Performance V-8 was never available with factory-installed air conditioning.

Myth 9: Some 289 High Performance V-8s were fitted with the Thermactor California emissions system (air pump).
False: Not one of them was ever fitted with the Thermactor air-pump emissions system.

Myth 10: Some 289 Hi-Po blocks have screw-in freeze plugs.
False: None was ever factory equipped.

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Oiling System Security

The 289 High Performance engine was fitted with the same type of oil pump, pickup, and pan found with the 2V/4V engines. When you rebuild the Hi-Po, opt for a high-volume oil pump for improved lubrication at high revs. Install a new pickup as well.

Although it is rumored all 289 High Performance engines had screw-in oil-gallery plugs, not all of them did. When you find press-in plugs, replace them with screw-in plugs when the block is being machined. Make sure your machine shop does a thorough job of cleaning the block and all of the passages afterward.

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Two Great Hi-Po Books

We recommend two terrific sources for 289 High Performance engine information. Mustang & Ford Small-Block V8-1962-'69 by Robert Mannel, published by RPM Press, is the best book we've ever seen on the small-block Ford. We're talking hundreds of pages of photos, text, and details on all '62-'69 221/260/289/302/351W small-block V-8s, including the '63-'67 289 High Performance. For more information, contact RPM Press, Dept. MM, 340 Clicktown Rd., Church Hill, TN 37642; e-mail bobmannel@compuserve.com.

Another good book is The 289 High Performance Mustang by Tony Gregory, available from Marv's Mustangs, Dept. MM, 12600 Leatherwood Ct., Raleigh, NC 27613; 919/848-6786; www.hipomustang.com. It has plenty of information related to 289 High Performance Mustangs. Register your '65-'67 289 High Performance Mustang while you're at it.

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