Steve Magnante's 1001 Mustang Facts. Steve Magnante

1966.

       Iconic yet problematic, the GT350’s sump kick-outs added capacity and build time.

      70 The deepened, cast-aluminum oil pans were designed by Shelby’s Peter Brock with sidesaddle sump “kick outs” on each side of the aluminum casting. These boosted capacity (from 5 to 6.5 quarts) without compromising ground clearance. Inside, Brock incorporated spring-loaded trap doors to keep oil concentrated around the pickup screen during high-speed cornering. The stock K-code oil pans were made of stamped steel and featured fixed baffles that were lacking on base 289 pan stampings. While efforts were made to sell off the new take-off units, most of the 561 factory-fresh oil pans were simply thrown out with the trash.

      71 Lacking his own aluminum foundry, Shelby sourced many of his special aluminum engine parts (oil pans, valvecovers, intake manifolds) from the Buddy Bar Casting Company of South Gate, California. Still active today, Buddy Bar was founded in 1951 and was named whimsically by its founder, Bud Barksdale. Shelby wasn’t Barksdale’s only automotive customer. Ford collaborated with Buddy Bar Castings on countless projects/products including items for the 1960s LeMans and NASCAR Boss 429 programs.

      72 Buddy Bar wasn’t the only supplier of Shelby’s bolt-on aluminum engine parts. Offenhauser cast the majority of the dual-plane, single 4-barrel GT350 intake manifolds used in 1965; Dearborn Steel Tubing provided the finished machine work. Research is still active in pinpointing exactly where the intake manifold conversions were performed: on Ford’s Cleveland, Ohio, engine assembly line or by Shelby’s minions at the LAX facility. Such “open-heart surgery” on any engine is a highly warranty-sensitive topic (dirt entry, oil leak issues, etc.). Most automakers prefer not to have their engines opened up by pre-retail-sale mechanics.

      73 Another headache-inducing modification made to 1965 and 1966 GT350s was the substitution of the free-flowing 289 cast-iron Hi-Po exhaust manifolds with (even better) steel tube headers. Supplied by Cyclone, they helped boost output from 271 to 306 hp and had to be installed from underneath each car by the same pit workers in charge of the oil pan. Like the labor-intensive aluminum oil pans, the headers were dropped after 1966. Incidentally, Cyclone’s adroitness with precision-bent steel tubing resulted in a contract to supply four-point roll bars for the 1965 GT350-R Competition Model. At $5,995, only 36 R-Models were built. Records show the last one was sold during the 1967 model year.

       Shelby tried to find homes for the 2,939 sets of Hi-Po 289 exhaust manifolds removed from 1965 and 1966 GT350’s but in the end, the vast majority was scrapped. Fact No. 73 tells the exhausting story.

      74 After May 2, 1966, 289 small-blocks received a revised rocker arm with “side rails” added to center the rocker arm atop the valves-tem. Previous Ford small-block rocker arms relied on narrow, rectangular guide slots cast into the cylinder heads that maintained rocker-to-valve alignment via pushrod contact. The redesigned rocker arms, cylinder heads, and pushrods are not interchangeable. Taller rocker covers were needed to clear the revised rocker arms, giving late 1966 and 1967 289s a wider overall appearance than earlier engines.

      75 The Hi-Po 289 escaped the May 1966 switch to rail-style rocker arms. Because of its solid lifters, the Hi-Po was fitted with threaded rocker arm studs and locking nuts to allow for valve lash. (The hydraulic lifters used on the 200- and 225-hp 289s provide the lash and didn’t require this adjustability.) Thus, Hi-Po 289s built through the end of 1967 do not share their rocker arms, pushrods or cylinder head castings with lesser 289s.

SUSPENSION AND BRAKES

      76 The SOHC 427 engines fitted to Ford’s mini-fleet of ’65 Mustang A/FX drag cars were too wide to fit between the Mustang’s stock front spring towers. To make room, Holman & Moody removed the towers entirely and filled the gaps with flat metal panels. The stock coils and towers were replaced with a Ford-designed horizontally arranged torsion-leaf setup. Great for drag racing in a straight line, the torsion-leafs imposed drastic positive camber changes on hard acceleration, and street use was strictly forbidden by Ford. Engine bay space was so limited that the steering boxes had to be relocated outside of the frame rails, which disturbed steering geometry. The geometry issue was solved by sourcing Australian right-hand drive (RHD) steering boxes from Fords built Down Under.

      77 Ever wonder why the 1966 Shelby GT350 went from 15- to 14-inch-diameter rims? It wasn’t a move to decrease vehicle height or drop the center of gravity in search of even better handling, although it did those things. Rather, after specifying 7.75-15 Goodyear Blue Dot race tires in 1965, Shelby and his workers found they had to spend a lot of time trimming the stock Mustang wheel lips to clear the larger diameter tires. By switching to 14-inch Goodyears for 1966, more than an hour of handwork per car was saved and the tire-rub problem was cured.

      78 Pre-production GT350 track testing revealed the stock upper shock absorber mounts (a.k.a. “beehives”) were too thin and needed fortification to maximize the effectiveness of the Koni shock absorbers at the front of the car. The simple remedy was the addition of two 3/4-inch flat washers atop each beehive to distribute localized stress better. Each washer was tack welded in position to prevent loss during assembly and service. Interestingly, these reinforced mounts were installed at the San Jose Mustang plant rather than at Shelby’s 6501 Imperial Highway conversion facility.

      79 The Mustang’s Falcon economy car roots are closer to the surface on 6-cylinder models than on V-8 cars. While V-8–powered ’Stangs were factory equipped with 10-inch drum brakes and five-lug hubs/wheels, base models with the 170- or 200-ci 6 rolled on the Falcon’s four-lug hubs and wheels. Early 1965 V-8 Mustangs came standard with 13-inch rims. These five-lug, 13 × 4½–inch-diameter hoops are very rare today because 14-inch rims and tires were optional for as little as $15.67 (black sidewall, nylon).

      80 Mustang spotters in the 1964–1966 time frame knew to give extra respect to anything rolling on redline tires. That’s because Ford specified beefy 6.95×14 Firestone dual red-band tires any time the 271-hp Hi-Po 289 was ordered. Buyers who wanted a little more anonymity could revert to same-size whitewalls or blackwalls at no extra charge. I’ll take the redlines!

      81 The 15-inch rims were typically found on full-size Ford models such as the Galaxie and LTD, but early in the Mustang production run, it was possible to order 5.70 or 5.90×15 tires and rims as part of the handling package on V-8 cars. Because of tight clearance, they were canceled in September 1964. After that, the next (non-Shelby) 15-inch Mustang wheel offering didn’t become available until 1969.

82 Part of the 1965 GT350’s reputation as a brutal, no-compromise beast stems from the replacement of the K-code Mustang’s Traction-Lok 9-inch rear axle with a ratcheting differential sourced from Detroit Automotive. The so-called Detroit Locker replaced the Traction-Lok’s conventional spring-loaded friction clutches (also available in the smaller 8-inch Hotchkiss-style rear axle) with a ratcheting differential. Free from clutch slippage, the locking differential delivered full power, equally, to both rear tires. The downside was its on/off nature and aggressive engagement characteristics. When cornering, the unit tended to (either) emit loud clicking sounds as the ratcheting gears rode past each other, or turn the inside tire at the same speed as the outside tire with the attendant chirping sound of tires squealing in protest. But in a straight line, the added stability of equal tire thrust was its virtue. Shelby made the Detroit Locker an extra-cost option for 1966.

       This original 1965 GT350 Detroit Locker displays the “dog gear” ratchet assembly that made it lurch, and work so well. See Fact No. 82 to learn why Ol’ Shel made it an option for 1966 and beyond.

      83 Carroll Shelby went to extreme measures in 1965 to cure Mustang’s penchant for violent axle hop on full-throttle acceleration. A pair