Ford rated its ‘65 289ci high performance V8, better known as the “HiPo” or “K-code” engine, at 271 horsepower at 6,000 rpm with peak torque of 312 lb-ft at 3,400 rpm. This updated K-code-inspired engine built in Part I should do better for a number of reasons – including less friction in the cylinders, higher flowing exhaust and much-improved valvetrain.
As described earlier, the longtime owner of a ‘65 K-code Mustang needed a new engine. He had components from the original 289 engine, including the cylinder heads, intake manifold, exhaust manifolds, distributor and timing cover. The original short-block was traded in as a core for a fresh Ford remanufactured short-block that was used for a rebuild in late ’70s. As part of a magazine tech story in the ‘80s, the solid-lifter cam was replaced with a hydraulic version, and an aluminum intake manifold was installed.
Restoring the engine to concours condition would have been expensive and time consuming—so the owner chose to “reKreate” the K-code engine with modern performance parts while maintaining much of the 289 HiPo character. He then added a couple more touches that were similar to the K-codes modified for the Shelby GT350 line.
CNC Motorsports in Brookings, South Dakota, handled all the machine work and assembly. The block was bored out .040-inch over for a set of SRP pistons from JE Pistons. A good portion of the performance gains can be attributed to these pistons because they’re lighter, have less surface area on the skirts and feature thinner rings than the original pistons.
The full rotating assembly, including a new ATI damper and a resurfaced flywheel, was balanced, then the short-block was assembled with ARP fasteners, Clevite bearings, Milodon oil pump and 5-quart pan. The original heads were treated to bronze valve guides, new seats and a 45-degree valve job, then assembled with Ferrea stainless-steel valves, Comp Cams valvesprings, and Comp Cams Magnum roller-tip 1.6:1 rocker arms. Final engine assembly included MAHLE MLS head gaskets, the original intake manifold and a Quick Fuel HR-450 carburetor.
The driving force behind two days of dyno testing was to compare two Comp Cams camshafts that reflect the original HiPo cam and the famed Le Mans cam that Ford offered through the Muscle Part catalog in the ‘60s (PN C7FE 6250-A). When the current owner purchased the K-code Mustang in ’72, the Le Mans cam was in the engine.
Ideally, the dyno testing would have been conducted with the two vintage bumpsticks in keeping with the goal of preserving the K-code engine character. In fact, the Le Mans cam was sent to Comp Cams for analysis on its Adcole 911 gage. According to the manufacturer specs, the Le Mans cam had a lobe lift of .330-inch for both intake and exhaust. The Adcole report said the lobe lift on the intake side ranged from .307-inch to .321-inch while the exhaust side ranged from .312-inch to .324-inch. The original specs also indicate 216 degrees duration at .100-inch lift. The Adcole report indicated a range of 214.8 to 216.5 degrees across all 16 lobes. It’s safe to assume that manufacturing variables and wear over the years has led to inconsistency in the original cams, so let’s see what’s available that closely matches those legendary cam profiles.
The original 289 HiPo cam (PN C30Z-6250-C) had 310 degrees advertised duration (194 degrees at .100-inch lift) with a .460-inch total lift at the valve and lobe separation angle of 114 degrees. The problem with comparing modern cams with those from the ’60s is that SAE hadn’t implemented the standard .006-inch valve-lift spec for advertised duration, and Ford didn’t list duration at .050-inch lift, which is today’s most-used comparison tool.
According to Billy Godbold of Comp Cams, however, the velocity limit of the Ford .875-inch tappet means that the .050-inch lift should be 30 to 40 degrees more than the .100-inch lift listed by Ford for its performance cams in the ’60s.
“The 194 at .100 is more in the 224-234 at .050 range,” estimates Godbold.
By comparison, the Comp Cams Nostalgia Plus 271S cam is designed to replicate the original HiPo camshaft “character” with a more aggressive, dual-pattern lobe design. This cam has a lobe separation of 112 degrees and gross valve lift of .495-inch intake and .490-inch exhaust. Duration at .050-inch is 225 intake and 232 exhaust–so it’s very close to the original HiPo cam.
Teamed with Comp Cams lifters and .080-wall, 5/16-inch-diameter chromoly pushrods, the Nostalgia Plus cam was broken in using BR40 Driven Racing Oil. This 10W-40 oil has a proper zinc and phosphorus formula to protect flat-tappet camshafts. The oil is also suitable for a full day of dyno testing after break-in, which comprised 30 minutes on the dyno under various RPM and loads. The break-in setup also included a shop carb and ignition system—both were known factors to ensure a safe startup.
Following the break-in procedure, the valve lash was rechecked at .012-inch and the oil filter removed for inspection. The original dyno game plan was to use the factory HiPo dual-point distributor, however, a crack was discovered in the shaft just before installation. So the shop’s MSD system remained for dyno testing. Timing was set at 35 degrees total advance. The shop carb was then swapped out with the Quick Fuel HR-450, which is close to the 480 cfm Autolite found on the 289 HiPo engine. The original plan also called for the factory exhaust manifolds on the baseline test, however, they wouldn’t fit on the dyno stand. A set of JBA Performance Exhaust shorty headers that will be used when the engine is installed in the ’65 Mustang was bolted on for the dyno runs.
As expected, the small-block Ford—now displacing a total of 294.32 cubic inches—performed better than the original 289 HiPo with a final pull of 308.1 horsepower at 6,000 rpm. Peak torque was 323 lb-ft at 3,500 rpm. The shop probably could have pulled a little more from the engine, since the engine was running rather rich at around 11.5:1 AFR. However, no one in a race shop that works with high-horsepower combinations could find jets small enough to lean out such a small carb.
The next test was a straight A-B comparison between the stock intake manifold and an Edelbrock Performer RPM intake. According to Edelbrock, this manifold is an evolution of the famed FB4 intake that was rebranded for the Shelby version of the ’65 Mustang. The GT350 started out as a K-code Mustang, and the engine was upgraded with the Shelby aluminum intake, a 715 cfm Holley carb and Tri-Y headers for a 306 horsepower rating at 6,000 rpm with peak torque of 329 lb-ft at 4,200 rpm.
The intake swap alone produced a horsepower reading of 331.5 at 6,000 rpm with peak torque of 326.4 lb-ft at 4,100 rpm, so we’re well within the Shelby GT350 jurisdiction. Again, the AFR was very fat around 11.8:1. With the Edelbrock manifold, the peak torque didn’t improve that much but the torque curve moved upwards noticeably to help generate the added horsepower at higher RPM.
The final dyno test involved swapping in a Comp Cams cam that resembles the Ford Le Mans camshaft. The Ford cam (PN C7FE-6250-A) sported specs of 318 degrees advertised duration on the intake (216 degrees at .100-inch lift) and 304 degrees advertised duration on the exhaust (216 degrees at .100-inch lift). Total valve lift was .510-inch, and the lobe separation angle was 108.5 degrees. Using Godbold’s estimates, this cam would be around 250-256 degrees duration at .050-inch lift.
The Comp Cams Magnum 282S comes with 235 degrees duration at .050-inch lift and gross valve lift of .528-inch. Lobe separation is 110 degrees. The cam was heavily coated with Driven assembly lube before installation. A fresh oil filter was spun on, and a fresh supply of Driven BR40 break-in oil was poured into the crankcase after the engine was buttoned up.
Since the dyno schedule was getting tight, a Quick Fuel HR-600 replaced the HR-450 to combine a couple of planned A-B tests. Following a couple pulls, the carb was re-jetted to achieve a 12.4:1 AFR. The result was a pull of 350.4 horsepower at 6,200 rpm with peak torque of 330.1 lb-ft at 4,800 rpm.
The K-Code Finds a Home
It’s obvious the engine is handicapped by the unaltered cylinder heads as the power simply falls off the table at about 6,000 rpm. But it’s a great sounding engine with plenty of pep for cruising and shows. Remaining chores included installing the engine at Whipple Racing in Rapid City, South Dakota, replacing all the wiring forward of the firewall and installing a JBA 2.5-inch stainless-steel exhaust system. The final touch was bolting on a set of American Racing Torq-Thrust wheels and BFGoodrich Radial T/A tires.