The failure of the Banshee did not mean the end of the OHC six, which finally went into production in the summer of 1965. That fall, it replaced a Chevrolet-derived 215 cu. in. (3,529 cc) pushrod six as the standard engine of the 1966 Pontiac Tempest/Le Mans.
In its initial form, the Pontiac OHC six displaced 230 cubic inches (3,769 cc), the same as the pushrod six used by the Chevrolet Chevelle/Malibu. The base engine, with a mild cam and a single-barrel Rochester carburetor, made slightly less torque than the Chevrolet engine — 216 lb-ft (293 N-m) to the Chevy’s 220 lb-ft (298 N-m) — but substantially more power: 165 gross hp (123 kW) to only 140 hp (104 kW) for the OHV Chevy. The OHC engine was not enough to make the Tempest a fast car, but it was a bit quicker than most contemporary American sixes.
The automotive press had known the OHC six was in the works for more than a year, but its arrival still made a great splash. Nearly every automotive magazine ran in-depth articles on the new six, speculating what it heralded for future Detroit engines. The buff books were particularly excited about the optional four-barrel version of the new engine, which Pontiac advertised as the answer to exotic European engines.
The four-barrel OHC engine had the same displacement as its more mundane sibling, but had new intake and exhaust manifolds, a hotter camshaft, and a higher compression ratio. In 1966, it was rated at 207 gross horsepower (154 kW) and 228 lb-ft (309 N-m) of torque, which was, as Pontiac advertising inevitably pointed out, more than many small-block V8s of the time. Chevrolet’s basic 283 cu. in. (4,638 cc) engine, for instance, was rated at only 195 hp (145 kW).
The four-barrel engine was marketed as part of a Sprint package that included stiffer shocks, side stripes, and other cosmetic details. Priced at $126.72, the Sprint package was available on any Tempest or Le Mans except station wagons. Pontiac marketed it as a European-style sports sedan, although most reviewers saw it as a sort of six-cylinder GTO. Naturally, the Sprint wasn’t as fast as the GTO, but its straight-line performance was more than adequate — 0-60 mph (0-97 km/h) took less than 9 seconds and top speeds of 115 to 118 mph (185 to 190 km/h) were possible. With less weight on the nose than a GTO, the Sprint also handled and stopped better. The hotter six was not particularly strong below 3,000 rpm, but it was tractable enough and many reviewers were entranced with its Jaguar-like growl.
Indeed, the Jaguar comparisons were tempting enough that Pontiac ad man Jim Wangers persuaded Doc Watson of Hurst Performance Products to install a Sprint engine and four-speed in a well-worn 3.8 E-Type. Hurst turned it over to Car and Driver, which found it somewhat slower than a healthy Series I E-Type, so Hurst added a trio of Weber carburetors and a few other shade-tree hot-rodding tricks that brought the engine to a claimed 315 horsepower (235 kW). Despite the magazine’s enthusiasm, the Pontiac-engined Jag didn’t inspire a raft of imitators, but it did attract a lot of attention, which was the point of the exercise. (The converted car was later purchased by Ford engineer Don Coleman, who substituted a 300 cu. in. (4,918 cc) Ford six for the Pontiac cammer.)
The publicity and favorable reviews were not enough to make the Sprint a runaway success. Total production for 1966 was fewer than 20,000 units, compared to nearly 97,000 ’66 GTOs. While the hot OHC engine was novel, it was not powerful enough to entice horsepower-crazed teenagers and the few customers interested in fuel economy in 1966 usually settled for the base engine. (Pontiac claimed the Sprint engine was capable of 20 mpg (11.8 L/100 km), but based on Popular Mechanics owner surveys, even the base engine was hard-pressed to return more than 17.5 mpg (13.4 L/100 km) in normal driving.) Even Car and Driver, for all its enthusiasm for the concept, reluctantly concluded that the V8 was the more sensible choice for the intermediate A-body. Despite the OHC engine, the Tempest/Le Mans Sprint was no sports sedan and many observers wondered if the hot six would do better in a smaller, lighter, sportier car.
By the time the Tempest/Le Mans Sprint entered its second model year, Pontiac was busily readying the Firebird for its mid-year introduction. When the Firebird went on sale in late February 1967, the 165 hp (123 kW) OHC six was standard and the Sprint package as one of four engine options.
On paper, the Firebird looked like a much better home for the Sprint engine than did the A-body Tempest, but the real-world results were less edifying. Although the Sprint engine was now rated at 215 horsepower (160 kW) and 240 lb-ft (325 N-m) of torque, most reviewers found the Firebird Sprint noticeably slower than the 1966 Tempest/Le Mans Sprint, particularly with the California emissions package. Part of the problem was the fact that the Firebird was not that much lighter than the Le Mans despite smaller dimensions; in fact, Car Life‘s well-equipped 1967 Firebird Sprint was actually 40 lb (18 kg) heavier than their 1966 Le Mans Sprint hardtop coupe. The Firebird Sprint handled marginally better than its V8 counterparts did, but it suffered all the suspension infirmities of all early F-bodies, including excessive wheel hop, a choppy ride, and a tendency to lose composure on uneven surfaces.
As with the Le Mans, the Firebird Sprint’s greatest problem was price. Although the four-barrel engine package was not particularly expensive, at $105.60, the 285 hp (213 kW) 326-HO actually cost about $10 less and mated better with the automatic transmission that most buyers preferred. Fewer than 25% of Firebird buyers opted for either OHC six.
Pontiac planned to drum up some interest with a special performance edition known as PFST (Pontiac Firebird Sprint Turismo), a Camaro Z/28-style homologation special for SCCA competition. Developed by engineer Herb Adams, the PFST used a modified version of the Sprint engine fitted with three Weber 40 DCN carburetors that protruded through the hood into a tall reversed scoop. The suspension was extremely stiff with stout anti-roll bars front and rear, giving excellent handling at the expense of a rather brutal ride. Pontiac let magazine testers drive the PFST prototype, but the new model didn’t make it to production. The triple Webers ran afoul of GM’s new ban on multiple carburetion and even after substituting a bigger Rochester Quadrajet, the modified engine was too loud to pass drive-by noise regulations.
Racing driver John Fitch, who had previously had a modest business selling modified Corvairs, developed his own tuned Firebird, also using the OHC engine. Unfortunately, the package was too expensive for most buyers. Fitch built only a handful of modified Firebirds, only one of which had the six-cylinder engine.
THE DECLINE AND FALL
Going from advanced engineering chief to chief engineer and then general manager was a mixed blessing for John DeLorean. His increased authority also chipped away at his former autonomy — there was ever-increasing pressure to meet cost targets and adhere to conservative corporate policy. DeLorean’s clashes with senior management were seemingly endless, which made him many powerful enemies within the corporate hierarchy.
The OHC six eventually became another point of contention. DeLorean’s immediate superiors, GM group vice president Roger Kye and executive vice president Ed Cole (who became GM president in the fall of 1967), were always unhappy about its high costs. Although Mac McKellar had done everything possible to minimize those costs, including sharing some parts with the contemporary Chevrolet six, the OHC engine was still more expensive to build than was its Chevrolet cousin. The OHC six also had higher warranty costs; while the timing belt itself was reliable, there were problems with premature camshaft wear and sticking valve lash adjusters. None of these issues was insurmountable, but they did nothing to win the confidence of an already skeptical corporate management.
For 1968, Pontiac stroked the OHC six from 3.25 to 3.53 inches (82.6 to 89.7 mm), bringing total displacement to the same 250 cu. in. (4,095 cc) as Chevrolet’s bigger pushrod six, introduced back in 1966. Increasing the OHC engine’s displacement was primarily intended to provide more torque for the heavier 1968 A-bodies and help the engine better cope with the new 1968 federal emissions standards, but Pontiac also added a new crankshaft with 12 counterweights rather than four, similar to the crank in the Chevrolet 250.
Pontiac claimed that the base OHC six now had 175 gross horsepower (131 kW), 10 hp (7.5 kW) more than before and 20 hp (15 kW) more than the pushrod Chevrolet six. Both the base and Sprint engines also had more torque: 240 lb-ft (325 N-m) and 255 lb-ft (346 N-m) respectively. However, the longer stroke made the Sprint engine noticeably less eager to rev, so its performance was not notably improved. Pontiac made a last effort to rectify that in 1969 by introducing two new camshafts for the Sprint engine. Cars with automatic again had 215 hp (160 kW), but slightly more torque, now 260 lb-ft (353 N-m); manually shifted cars, with more valve overlap, had 230 hp (172 kW) and 255 lb-ft (346 N-m).
Unfortunately, the interest of both buyers and the enthusiast press had by now mostly faded, so sales of the six continued to decline. That in turn made it harder than ever for Kye and Cole to accept the OHC engine’s higher costs. A further problem was that the OHC engine was too tall to fit in the engine bay of the forthcoming second-generation Firebird without bulging the hood. As with the Banshee, DeLorean continued to fight for the OHC engine, but it was to no avail. DeLorean left Pontiac for Chevrolet in early 1969 and the OHC expired soon after that; starting in 1970, Pontiac would buy the cheaper 250 cu. in. (4,095 cc) Chevrolet six instead.
DeLorean’s successor at Pontiac, F. James McDonald, was a production man, not an engineer, and shared neither DeLorean’s interest in technological novelty nor his penchant for battling management. Once the OHC six was dead, the OHC V8s were also canceled, as were a number of experimental derivatives of the six. Pontiac’s engineering focus shifted to emissions control; high-revving, high-performance engines seemed increasingly anachronistic.
The cancellation of the OHC six was unfortunate because less than five years later, the OPEC oil embargo sent Pontiac engineers scrambling to find smaller, more fuel-efficient engines. Unlike Buick’s resurrected V6, whose tooling had been sold to Kaiser Jeep and then to AMC, the tooling for the cammer was probably long gone by then, leading Pontiac to develop the undistinguished 301 cu. in. (4,942 cc) V8 instead. Had the OHC six survived, it probably would have done very well in the seventies. Even the Sprint might have found its niche, appealing to performance-minded buyers who couldn’t afford the insurance premiums on a GTO.