Jerry Titus
December 18, 2013
Photos By: Source Interlink Media Archives

With a high center of gravity, a butt-headed silhouette, a theoretically unsophisticated suspension system, a heavy forward weight bias, and a pot full of other limitations when considered as a race car, the Mustang is no "piece of cake” to convert to such an application. However, there are a bunch of imported sports cars with the same limitations, so Miles had plenty of experience to draw on, combined with many of the recent developments to come out of Shelby American as a result of their intense racing and research programs. While held to the basic Mustang configuration, their hands were relatively free to alter as they saw fit. After all, it was to be a separate model. Cost was a primary consideration, as they hope to hold the price of the street version to under $4,000 and the ready-to-race machine to under $6,000.

The first move was to reduce weight. Replacing the rear seats and upholstery with light pressed-paper trim and having the racing model assembled in San Jose less sound deadening and undercoating amounted to a huge chunk. In the racing version, the side windows are replaced with pull-up plexiglass units and all the internal regulator mechanism removed. The hood is duplicated in fiberglass. The front bumper is removed and the gravel guard behind it is replaced with a reshaped fiberglass covering that greatly increases air intake to the radiator. The small and somewhat functional vents in the fastback are removed and blanketed out via a fiberglass insert. These fancy little grille assemblies weigh 14 pounds each. The front seats are replaced by glass buckets, very light and efficient ones that retain the adjustment tracks.

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With just about the maximum in weight savings accomplished, it was then necessary to put pounds back into the car in the form of competition options. The street car will have six-inch rims on steel wheels. The race car uses seven-inch wide magnesium wheels. Both are 15 inches in diameter. Goodyear 6.50/6.70 "Red Dots” are mounted for competition. Brakes are disc in front and 10 x 2.5-inch drums in the rear. These are borrowed from bigger cars in the Ford family. The live rearend is of Galaxie derivation with limited-slip and heavy-duty axles. The street model gets an "export,” or heavy-duty, radiator. The racing version uses a Galaxie HD/Air Conditioning radiator with a very large oil cooler mounted directly behind it. Both have the Mustang HD suspension with an extra fat front sway bar and Koni shocks. For better rear axle control, the race car has special radius rods or torque arms in the rear that run above the leaf springs and into the unitized body near the front pivots of these springs. For better geometry in the front, the inner pivot points of both upper and lower control arms are altered—the top arm lowered and the lower arm moved outboard. Despite these additions, the racing model tips the scale at a mere 2,153 pounds.

The 289 High Performance is the powerplant in both models, but the racing version is a hand-assembled unit with a special camshaft, roughly the same except for a grand's worth of tender, loving care that net it a 20-percent increase in performance. Both use the new Holley four-barrel with a special intake manifold. A very efficient set of side-routed headers are used for racing. The competition engine has a large, steel sump; the street version a cast-aluminum pan with extra capacity and big fins. Both connect to Ford's close-ratio four-speed transmission.