Fifteen years ago, restoring was the thing to do. As the ´66 Mustang GT was slowly brought back to life during the early ´80s, the tired old 302 two-barrel that someone had installed during the ´70s was replaced by a Fred Jones Remanufactured A-code 289 long-block, topped by an original cast-iron intake and Autolite four-barrel carb. In keeping with the restoration theme for the engine's installation story in the June ´84 issue of Mustang Monthly, the 289 was also equipped with the log-style exhaust manifolds, single-point distributor, and enclosed ´66-style air cleaner. Although the Autolite eventually gave way to a Holley from some other long-lost project, and a more-efficient Petronix ignition took over for the finicky single points, the little 289 with C4 automatic purred along with all the fury of a lazy housecat.
Then along came Mustang & Fords and the move toward restomod, a theme that maintains the GT's vintage looks but allows for modifications to improve performance. Obviously, one of the major keys to more Mustang fun is more horsepower, something we decided to address by bolting modern technology on top of the vintage 289 short-block. Although the replacement engine is now 15 years old, the car has been used sparingly, mainly as a weekend cruiser, so the basic short-block is still in good shape. Basically, we modified four major areas of the engine--heads, induction, camshaft, and exhaust--all intended to increase the fuel/air mixture flow through the engine.
On a Roll
At the center of our modern 289 is a Crane "Retro Roller" camshaft, a special 5.0-style roller lifter cam with a smaller base circle diameter to fit into the early 221 through 302 blocks. In addition to the obvious friction savings with the roller lifters, the roller cam also allows more-aggressive ramps for higher lifts. The Crane 289 Retro Roller specs out with a .520-inch intake lift and .542-inch exhaust lift with 1.60:1 rocker arms. Crane's Retro Roller camshafts, also available for 351 Windsors, Boss 302s, and 351 Clevelands, are supplied with a kit for installation into the early blocks. Included are the roller lifters, guidebars, guidebar hold-down plate (commonly called the spider), reinforcing bar, and mounting hardware, which attaches the spider to the block without drilling or machining. Crane also supplies the correct-length pushrods, which are needed to accommodate the taller roller lifters. For compatibility with the roller cam's steel construction (as opposed to cast-iron for the 289 cam), a special steel distributor gear is also required to prevent wear. A variety of steel gears are available from Crane, depending on the distributor you're using. Look for a compete and detailed Crane Retro Roller cam installation article in a future issue.
Heads Up
Originally, we planned to install Ford Motorsports' (or Ford Racing Performance Parts', by their new name) cast-iron GT-40 heads on our 289 to stay more in tune with the "original" theme, even painting them Ford blue for a more stealthy appearance. However, when we discovered that the M-6049-L303 cast-iron heads were on backorder, we were "forced" to make the upgrade to aluminum "Turbo Swirl" GT-40X heads, PN M-6049-X305. These heads boast larger valves--1.94/1.54-inch compared to the 1.67/1.45-inch valves in our original 289 heads--and larger ports to offer substantial airflow improvement for more horsepower, especially at the upper end of the rpm range. Another positive for aluminum heads is the weight savings over the front end. At just 22 pounds each, the GT-40X heads weigh some 50 pounds less than the factory cast-iron heads, a benefit to both acceleration and handling.
On the down side, however, we must admit that these newer-style heads have slightly larger combustion chambers (58cc compared to the factory 289's 54.5cc chambers), because they are primarily designed for late-model fuel-injected engines. On our 289, with its flat pistons, we may have lost up to half a compression point. Ideally, a head swap like this on an older engine would also include a different piston to restore the compression ratio, or shaving the heads, but that's getting away from our "bolt-on" angle. When using the GT-40 heads on an early engine, Ford Racing Performance Parts recommends checking the valve-to-piston clearance, especially if your pistons don't have valve reliefs. The GT-40X heads utilize late-model bolt-on rocker arms and the small, tapered AGSC-32C Motorcraft spark plugs. Since we were changing rockers, we opted for the lightweight needle-bearing, roller-tip, 1.60:1 rockers from Crane Cams. A bolt-on style that doesn't require pushrod guide plates, the rockers come with pedestal mounts and bolts. Be sure to follow Crane's recommended procedure for adjusting the hydraulic lifter pre-load.
With the aluminum roller rockers, we also needed additional clearance under the valve covers. Tony Branda Performance offers the perfect solution for vintage Ford enthusiasts with its taller-than-original "Cobra--Powered by Ford" finned aluminum valve covers. These covers will give us the clearance we need for the roller rockers, yet still maintain our intended vintage appearance. As a side lesson, when installing the spark plugs, we noticed that the plugs didn't go into the heads smoothly. A quick check revealed that the parts store had sent plugs with the wrong threading. Instead of a tapered plug, they had supplied plugs with threads that stopped abruptly. Fortunately, this was discovered before tightening the plugs into the soft aluminum, although we did suspect some minor damage in one hole. The lesson: Don't assume the parts store has sent the correct parts. Always double-check.
Getting Inducted
We've always like the combination of Weiand Stealth aluminum intake manifold and Holley four-barrel on a modernized small-block Ford. Although technically a dual-plane design, the Stealth manifold also produces good power at higher rpm, more like a single-plane, which makes it a good, all-around choice for street-performance engines. To top off the Stealth intake, Holley recommended one of its 600-cfm, 4160-series four-barrels with vacuum secondaries. Designated for ´61-´67 Ford V-8 engines, Holley PN 0-80457S comes with an electric choke, Ford throttle hookups, and polished body. And like all Holleys, our four-barrel is infinitely tuneable with a variety of accessory parts from Holley. Since we had the old fuel pump off for the cam swap, it made sense to replace it with a high-performance fuel pump from Holley. Designed for continuous, high-rpm performance, Holley's mechanical fuel pump for small-block Fords flows over 80 gallons per hour, almost overkill for our mild-street small-block, but, as always, it's better to have too much fuel flow than not enough. Beautifully chromed, the Holley pump is a direct replacement for the factory mechanical pump.
For more efficient air cleaning, we stored the original enclosed A-code Ford air cleaner in favor of a reproduction 289 High Performance air cleaner from Tony Branda Performance. A classic, open-element design with chrome lid, the Hi-Po unit allows airflow from all sides, unlike the closed unit that pulled air through a single snorkle. For even better flow, a K&N Filtercharger was sandwiched between the cleaner top and bottom. Actually, K&N sent us a pair to try--PN E-1560 is the direct replacement for the 2-inch tall Hi-Po paper element, while E-1570 is about an inch taller. The taller K&N did allow enough hood clearance, so we used it for the additional filtering area.
Exhaust
With more air coming in, we needed to help get the exhaust out more efficiently. Headers were certainly a viable option, including Shelby-style Tri-Ys, but instead we chose to go with K-code 289 High Performance exhaust manifolds, obtained from National Parts Depot in Gainesville, Florida. Unlike the Fairlane installation we performed a few months ago ("Special Ks," Feb. ´99 issue), the Hi-Po manifolds basically fall into a Mustang, with no engine raising required. With their more streamlined shape and larger openings, the Hi-Po manifolds are much freer flowing than the regular log-style manifolds. As another plus, they seal to the heads better than tube headers, providing quieter operation.
To connect the manifolds to the factory GT dual exhausts, the A-code H-pipe was replaced by a Hi-Po H-pipe, also from National Parts Depot. On the Road and on the DynojetAfter buttoning down all the new high-performance equipment on our 289, and double-checking torque specs and fluids, we fired the engine, set the timing, and adjusted the idle and choke--only to discover a misfire. After confirming the correct spark plug wiring order, testing for vacuum leaks with starter fluid sprayed around the intake and carb, and yanking a few spark plugs to check their condition, we still couldn't locate the culprit. On the road, the engine ran rough at idle and low speeds, but cleared up under full throttle. We did find a couple of problems--a cracked vacuum hose at the transmission modulator (obviously caused by jostling the metal line when installing the heads) and a missing ground strap--but neither cured the problem.
With an appointment made for Dynojetting the new combination at Vinci High Performance in Orlando, Florida, we notified Joe Vinci that we needed some diagnosis advice as well. At the Vinci shop, Joe pulled a spark plug and immediately noticed what we hadn't--the plugs didn't reach all the way into the combustion chamber. Yes, the parts store had sent the wrong plugs for the second time. The replacement plugs had the correct thread taper, but the reach was only about half the correct length.
While replacing the short plugs with the correct-length plugs, one of our fears from the first spark plug foul-up (remember the incorrect thread taper?) surfaced as fact: The threads in the No. 2 spark plug hole were indeed mangled. Fortunately, with the short plugs, the cross-threading didn't extend all the way into the head, which allowed Vinci to repair the damage by retapping. However, the time spent on the plugs and the thread damage had cut into our Dynojet testing time, leaving us time for only a couple of pulls to obtain our final numbers.
The longer plugs definitely cured the misfire, as evidenced by the clean pull on the Dynojet. However, like Wayne Cook's Fairlane in an earlier issue, the Dynojet operator had to shut down the run at 4,500 rpm due to a drivetrain vibration. Because of the time spent on the plugs, there wasn't enough afternoon left to replace the U-joints or chase down the vibration. Although the first and only run showed a 16-25 hp increase across the board, topping out at 150 rear-wheel hp at 4,500 rpm, we were disappointed that we couldn't rev the engine higher to take advantage of its better breathing with the high-performance cam and heads.
On the trip home, the 289 pulled strongly, feeling a lot more like a healthy 289 High Performance four-speed than an A-code 289 automatic. And there's still some tuning potential because we haven't had a chance to play with timing, advance curve, and carburetor jets. Right after returning from the Dynojet, the C4 came out for a scheduled rebuild by the folks at Performance Automatic during their trip to Florida for the Fun Ford Weekend in Bradenton.
As soon as we get the trans back in the car, including new U-joints and balanced driveshaft, we'll take it back to Vinci High Performance for a return tuning visit to the Dynojet. At that time, we'll report on the performance C4 rebuild--and its effect on the rear wheel numbers--and the horsepower/torque numbers at higher rpm.