This story is not about a Ford 289 HiPo engine restoration. That ship sailed long ago when the factory ’65 short-block was used for a core charge during a rebuild in the ‘70s. It was an understandable move since no one could have predicted the value those original short-blocks would command today just because the VIN numbers were carved into the face of an iron block.
Rather, this article is about “reKreating” the 289 HiPo engine with modern parts while retaining as much of the K-code character as possible. The cost of restoring a 289 HiPo engine to Concours condition is too high, even if you can find NOS parts or surviving parts in good condition. Instead, this engine project will take advantage of new piston and camshaft technology along with upgrades developed for the lubrication, exhaust, and intake systems.
In the early days of the Mustang, the K-code was the only performance option — unless you spent a couple-thou extra for a Shelby GT 350 — which sported a modified 289 HiPo engine. The K-code engine was rated at 271 horsepower at 6,000 rpm with 312 lb-ft peak torque at 3,400 rpm. It was available from 1964 through 1967, and some 13,000 K-code Mustangs were built. This accounted for less than one percent of the 1.8 million Mustangs produced in that time span.
The K-code engine is easily identified from the other 289 engines when peering under the hood. It features a 2-inch-wide damper, compared to 1-inch-wide damper found on standard 289s. The K-code engine also has a centrifugal-advanced dual-point distributor, whereas standard 289 engines had a vacuum-advanced single-point distributor.
Perhaps the most iconic difference is heard and not seen; the solid-lifter camshaft that boasted specs of .460-inch total valve lift with 1.6:1 rockers and 310-degrees advertised duration. Ford also equipped the HiPo cylinder heads with threaded rocker studs and provided a slightly larger Autolite 480-cfm, 4-barrel carburetor with the K-code option.
This particular Mustang (and engine) has been in storage most of its life after the Ford remanufactured short block was mated to the original cylinder heads in the ‘70s rebuild. The car was used for a few tech articles which appeared in the old Petersen Publishing’s Mustang Monthly magazine. Most recently, it was used for recent web stories covering the installation of a new radio, another carburetor and ignition swap, new fuel tank, and significant front and rear suspension upgrades.
Constant overheating and an annoying internal knock prompted a decision to remove and disassemble the engine. Then a plan was developed to reKreate the K-code engine honoring as much of the original character as possible while using modern performance parts.
CNC Motorsports in Brookings, South Dakota, disassembled the engine and took care of the considerable machine work needed to ensure the 55-year-old cylinder heads, block, crank, and rods from the ‘60s were stout enough to support modern power parts. Here’s a quick rundown of the machine work:
- Block: Magnaflux, wash & shot blast, align hone, surface decks, install cam bearings and frost plugs, resurface bellhousing surface, bore to 4.040-inch, torque-plate hone.
- Flywheel: Grind surface.
- Crankshaft: Magnaflux, polish, balance w/ damper, and flywheel.
- Connecting rods: Magnaflux, resize both ends.
- Cylinder heads: Magnaflux, wash, machine spring pads, new seats, install bronze valve guides, surface deck, valve job.
The heads were assembled with Ferrea Competition Plus stainless-steel valves (1.780-inch intake, 1.450-inch exhaust), COMP Cams springs (125 lb seat, 285 lb open), ARP 3/8-inch rocker studs and COMP Cams Magnum 1.6:1 roller-tip rocker arms. These Ferrea valves were not only stronger than a stock replacement but four- to five-grams lighter. They came with a standard 45-degree seat angle.
The crankshaft that came in the Ford remanufactured short block from the ‘70s had already been turned .010/.010. There were no differences between the cast-iron crankshafts in all 289 engines, but HiPo cranks were carefully tested and selected for higher nodularity. HiPo engines also came with a thin, hatchet-shaped counterweight mounted next to the timing gear. This reman short-block didn’t have this counterweight. Since the SRP pistons from JE Pistons and ATI damper would all be new, rebalancing the entire assembly with the 20.4-pound flywheel was appropriate.
The connecting rods in a K-code engine are the same as standard 289 rods except that 3/8-inch bolts are used instead of 5/16-inch bolts. CNC Motorsports didn’t want to risk weakening the support structure around the bolt holes by drilling them out, so ARP Pro Series Wave-lok bolts were made from 8740-Chromoly steel with a yield strength of 200,000 psi. ARP main and head bolts were used in the engine assembly as were Clevite bearings from MAHLE Aftermarket and Driven Racing Oil assembly lube.
One of the biggest performance gains using modern parts was the piston selection. The original pistons were massive at over 580 grams while the line of SRP pistons from JE tipped the scales at 483 grams. Besides having less surface area than the old pistons, the new pistons feature coated skirts and sport thinner rings — reducing the friction load considerably in the cylinder. Also, CNC Motorsports converted the piston pins to full floating — again, reducing friction in the rotating assembly. The pistons are constructed from 4032 aluminum.
The factory 289 HiPo engine had an 11.5:1 compression ratio when it was first introduced in the 1963 Fairlane. That slipped to 10.5:1 in 1965, but still too high for today’s pump gas with an iron head. So, the SRP pistons were made to deliver a 9.9:1 compression ratio.
Milodon manufactures a beautiful 5-quart replacement oil pan for the small-block Ford which features baffling for improved oil control around the pickup. A Milodon pump was also used in the buildup. The final modern upgrade for the long-block was a set of MAHLE MLS head gaskets. MLS, or multi-layer steel, has taken the industry by storm in the past decade, offering superior sealing over traditional composite gaskets. The embossments in the layers act as “springs” to fill in the gap should the head start to lift away from the block under severe cylinder pressure.
Topping off the engine for the first-round dyno testing was the original cast-iron intake manifold and a Quick Fuel 450 cfm carburetor. The original HiPo carb was a 480 cfm Autolite model, but they’re rather hard to come by these days. The original dual-point distributor was planned for this build, but at the last minute, a hairline crack was discovered on the shaft. Dyno testing would be conducted with a house MSD setup, and another solution would be sought for the final installation in the vehicle.
For photo purposes, the engine was buttoned up with the original timing cover, a new Edelbrock K-code water pump, ATI damper, original exhaust manifolds, and original valve covers. All ’65 289 HiPo engines were painted black with the traditional blue coming the following year.
Wait! What about the camshaft, you ask?
Part II of this story will cover dyno testing, which includes an in-depth look at two camshafts from COMP Cams reflecting the original HiPo specs as well as the famed Le Mans camshaft. The first is the Nostalgia Plus with numbers very close to the original HiPo camshaft. Second is the Magnum 282S grind. Both the original and Le Mans cams were used in the engine in the ‘60s and early-‘70s when the car rolled up most of its mileage. It will be interesting to see how modern interpretations from COMP fare on the dyno.
Additional dyno testing includes upgrading to a new Edelbrock intake manifold similar to the iconic FB4 intake rebadged for the Shelby GT350 engine. Other upgrades will include a higher flowing Quick Fuel carburetor and a set of JBA shorty headers. You can find a link to the Part II dyno testing here.