Jim Smart December 12, 2017

The 2018 Mustang GT owes its very existence to the pioneers that started it all 54 years ago. Thirty-two valves, charge motion, variable cam timing, and a dizzying redline on the order of 7,000 rpm with Ford’s high-tech Coyote. Wow! We’ve come a long way since pushrods, flat tappets, flattop pistons, cast iron, and small intake and exhaust ports. Yet, were it not for the Mustang’s very first high-performance V-8, the 289ci High Performance, we might not be where we are today.

The small-block Ford, known originally as the 90-degree Fairlane V-8 introduced in 1962 in displacements of 221 ci and 260 ci, was really impressive for its time. It was compact, lightweight, fuel stingy, and made a lot of power for its size. It wasn’t long before Ford engineers and product planners understood this tiny little V-8 needed greater displacement and the infusion of attitude.

In 1963, the 289 High Performance V-8 was introduced in the Ford Fairlane. It was an engine born to rev with a hot flat-tappet mechanical camshaft, screw-in rocker-arm studs, valve spring pockets, an Autolite 4100 series four-barrel carburetor, cast-iron headers, Brinnell-tested nodular iron crankshaft and high-performance connecting rods, a slide-on counterweight, a wider harmonic dampener, and ultimately a dual-point ignition system.

Because the 289 High Performance V-8 was produced in such limited quantities at Ford’s Cleveland Engine Plant early on, these engines had limited availability. You would have thought Ford’s sporty new Mustang would have blazed a trail from the stable with a 289 High Performance V-8 option from the start in April of 1964. It didn’t.

The earliest known “K” VIN Mustang is 5F07K100148, a pre-production Dearborn unit built specifically for Henry Ford II prior to the start-up of mass production at Dearborn on March 9, 1964. Aside from HFII’s one-of-a-kind Hi-Po Pony, the earliest known “K” VIN production Mustangs were bucked and built in late June of 1964 at the Dearborn, Michigan, assembly plant according to Scott McMullen, a Hi-Po historian who has done a tremendous amount of research on early K-code Hi-Po engines.

Scott says, “I am not aware of any other pre-production ‘K’ units with VINs besides 100148, though there are several engineering test cars that were featured in magazine articles. The earliest of these test cars was a convertible driven by Dan Gurney in February of 1964 that he referred to as a ‘prototype for production models.’ Test units appear to have been built at different times up until June of 1964.”

Scott adds, “The next batch of ‘K’ VIN units have scheduled build dates of June 7, 8, and 9 of 1964.” However, the evidence Scott has collected from these production units suggests the engines and corresponding bodies were built well after the scheduled build dates on the warranty plates. “The VINs are not necessarily in order with the date codes, so you have to look at other evidence to narrow down a ‘must have been built after’ date. VINs are not always in order with the date codes.”

Scott goes on to say, “The fourth edition of the Hi-Po Registry shows the first four known VINs are 158705, 158819, 159122, and 160242, though there is a VIN of 159333 taken from an engine of unknown origin. There are June 8 and 9 date codes (08F and 09F) from this early batch of cars extending out to VINs in the 162XXX range.”

Based on what Scott has told us, the first production “K” engine code Mustangs were built in the last week of June. Despite a lot of chatter through the years indicating some May Hi-Po units, none have surfaced to date.

For more than a half-century, the 289 High Performance V-8 has been more myth than fact. 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 V-8 is a warmed-up 289 with a hotter solid-lifter camshaft, cylinder heads designed for high rpm, a dual-point ignition engineered for higher revs, cast-iron exhaust headers, and a wider harmonic balancer to deal with increased reciprocating mass down under.

Unless you're restoring a K-code 1965-1967 Mustang or are interested in building an authentic 289 Hi-Po small-block for your non–K-code Mustang, there isn’t a whole lot of difference between a 289 High Performance V-8 and your standard vanilla 289-2V. 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 show you the basics of the 289 High Performance V-8 with quick facts you can use in your engine building and Mustang spotting. Keep in mind that there are some exceptions to the identification rules for K-codes that were built prior to June 29. And because we’re dealing with a lot of production unknowns from a half-century ago, be prepared to find just about anything out there.

For 1964½-1965, the 289 High Performance V-8 looks like this in black with chrome appointments with a mechanical high-performance cam, unique Hi-Po heads, dual-point ignition, special cast-iron exhaust headers, an Autolite 4100 four-barrel carburetor with manual choke, and more. The 289 High Performance V-8 was available only with a four-speed manual transmission that first year (except Canada where it was also available with an automatic).

For 1966, Ford went to a standard Ford Blue color on all of its engines, including the 289 High Performance V-8. The 1966-1967 Hi-Po was a carryover of what was available for 1965 with the exception being pent-roof valve covers for 1967. The Hi-Po was available with either a manual four-speed or three-speed automatic for 1966-1967.

The 289 High Performance V-8 was equipped with this unusual Autolite 4100 carburetor with manual choke. There has been some discussion about very early Hi-Po engines with automatic choke 4100 carburetors produced early in 1964, which would call for the Fairlane’s right-hand Hi-Po exhaust manifold with choke stove.

A dual-point Autolite ignition was employed on the 289 High Performance V-8. You can expect to see two possible distributors: early with an oil wick and later shown here, which is a completely different casting. These dual-point ignitions do not have a vacuum advance. If you unearth a dual-point distributor with vacuum advance, you’ve found one for a 1969-1970 Boss 302.

The Hi-Po has a wider harmonic dampener, as shown here, followed by a counterweight inside the timing cover. Both are used to work cohesively with heavier connecting rods inside with larger, heavier bolts.

Here are the two basic Hi-Po distributors side by side. On the right is the early 1964-vintage Hi-Po dual-point distributor with oil wick. Left is 1965-vintage dual-point, which is a completely different casting. Examine these castings for the part number and date code for an accurate assessment of what you’ve found.

The 289 Hi-Po alternator has a larger drive pulley to reduce alternator speed at high rpm. The same can be said for a generator-equipped Hi-Po for 1964½, which will also have a larger drive pulley.

The quickest way to ascertain a “K” vehicle identification number (VIN) Mustang is the fifth character (engine code). The VIN should also be stamped into the right-hand side of the block near the negative battery cable mounting boss if the vehicle is still so equipped. Only Hi-Po engines got stamped with the VIN of the vehicle they were factory-installed in. Beware of the fakes that may not have the original engine that are stamped with the vehicle’s VIN.

The 289 High Performance fender badge was factory-installed on “K” VIN Mustangs and Fairlanes. Just because the car has a Hi-Po badge doesn’t mean it is a factory Hi-Po.

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 are there for stability. Screw-in rocker-arm studs exist for durability. Outside of these factory nuances, the Hi-Po heads are the same as the 2V/4V heads.

The Hi-Po’s valvetrain includes these adjustable cast rocker arms, which worked fine in the 1960s. If you want real durability, opt for modern aftermarket roller rockers for less friction and superior durability.

The Hi-Po cylinder head has the same 57cc chamber and valve sizing as a regular 2V/4V head. This head is fitted with new-old-stock Ford valves. Early Hi-Po heads tend to have smaller chambers offering greater compression.

Look for 19, 20, or 21 cavity numbers on Hi-Po heads. If there isn’t 19, 20, or 21, then it is not a Hi-Po head.

The 289 Hi-Po’s intake manifold is the same as a regular 4V manifold. This is a C5OE-9425-A casting.

Down under, the 289 Hi-Po is fitted with reciprocals designed for high-rpm use. Look for this bright orange paint on the 1M crankshaft counterweights, which means the nodular iron crank has been Brinell-tested for strength. This means handpicked for the Hi-Po. Hi-Po connecting rods are basically the same forgings as 2V/4V engines with a “C3OE” number. Where they differ are larger rod bolts with broached heads for added strength.

Because the Hi-Po has more meat in its connecting rods, it mandates the use of this stamped-steel counterweight up front.

Because the Hi-Po has more meat in its connecting rods, it mandates the use of this stamped-steel counterweight up front.

Another myth is Hi-Po blocks. Look for this “HP” marking at the back of the block on all Hi-Po blocks. However, the block itself isn’t any different than a 2V/4V block. The wider main caps are what make the block assembly different.

These are the Hi-Po’s wider main caps, which were employed for strength. You can cop a Mexican 289/302 block and get wider main caps too. When you mate these wider caps to a 289 block, you will have to have the assembly line honed for precision bearing crush and accurate clearances.

This C5AE-6015-E block is a Hi-Po block. However, C5AE-6015-A doesn’t mean you’ve found a Hi-Po block. It means you’ve found a 1965 289 block. Main cap width is the Batman moment when you’ve found the real thing.

The 289 Hi-Po’s exhaust manifolds are a cast-iron shorty header, which offers better exhaust scavenging than the standard vanilla 289/302 exhaust manifolds.

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 camshaft is aggressive, with 0.460/0.460-inch valve lift and 310/310 degrees of duration. Lift at the lobe is 0.298/0.298 inch. Raw torque and horsepower come on strong at the same time in the high revs.

Here’s a closer look at the Hi-Po’s C3OE connecting rod with its larger 3/8-inch broached rod bolts. You can recondition conventional 2V/4V C3OE rods and fit them with ARP bolts to achieve the same strength.

Two types of bellhousings were employed in the mid-1960s. The smaller five-bolt bell (left) is a 1964½ element. The larger six-bolt bell (right) rolled into production for 1965 was engineered to reduce noise, vibration, and harshness. If you’re shopping for a block, it is crucial for you to be aware of this difference.

Flywheel selection is vital to smooth operation. Small-block Fords prior to 1982 had a 28-ounce offset balance flywheel/flexplate. From 1982-up, Ford went to a 50-ounce offset balance with the externally balanced small-block Fords. You do not want to accidentally choose a 50-ounce offset balance flywheel or flexplate for your 289 Hi-Po. Confirm offset balance size going in.