Mechanical Changes

The enforcement of the Clean Air Act of 1970 dictated changes to Pontiac's powerplant portfolio. Lowered compression ratios took center stage, touting compatibility with the new generation of low-lead and no-lead gasolines that were beginning to find their way into the marketplace. While this was bad news for performance fans, Pontiac did an admirable job of mitigating these horsepower-robbing factors.

Pontiac put out a print advertisement for the 1971 GTO that bluntly asked, "Does a low-compression engine mean the end of the GTO?" In it, Pontiac marketers calmed concerns that the GTO suddenly became a watered-down machine. The ad explained that the power from a crankshaft is only one portion of what is known as "tractive force," and Pontiac countered by altering the rear-axle ratios to compensate for the lowered engine output. According to Pontiac, a buyer would not notice any difference in performance between a 1971 GTO with the 400 and a 1970 GTO similarly equipped. The ad went on to state that the new 1971 455 H.O. GTO performed better than anything in Pontiac history at both low and top ends.

In compliance with the new federal regulations, both the Ram Air III and Ram Air IV 400s were dropped. The base engine became a 400/four-barrel with 8.2:1 compression and an 067 cam. It was rated at 300 horsepower at 4,800 rpm, with 400 lb-ft of torque at 2,400.

The first engine up the option ladder was the D-port 455/four-barrel. Equipped with an 067 cam and an 8.2:1 compression ratio, this engine was available only with a Turbo 400 automatic and was rated at 325 horsepower at 4,400 rpm, with 455 lb-ft of torque at 3,200.

The top engine option for the 1971 GTO, by taking the basic design of the Ram Air IV cylinder head with its tulip 2.11- and 1.77-inch valves and opening up the combustion chamber volume to 111 cc, Pontiac engineers increased this engine's breathing capability without going to a radical cam profile, which would hurt emissions. The cam was Pontiac's 068 with 288/302 degrees of advertised duration and 0.407-inch lift. The heads were topped off with a Ram Air IV-style aluminum high-rise intake manifold with removable crossover and a Rochester Quadrajet.

The rest of the 455 H.O. was fairly typical Pontiac componentry, with cast pistons and rods, a nodular-iron crank, and four-bolt mains. It was rated at 335 hp at 4,800 rpm, with 480 lb-ft of torque at 3,600. With such a massive amount of torque available and a redline of just 5,200 rpm, there was no need for forged bottom-end components.

All 1971 GTO engines were available with a standard three-speed manual, optional four-speed manual, or extra-cost automatic transmission.

The Judge Returns—and Then Retires

The Judge option returned for 1971, with the majority of the changes made to coincide with the updated styling. Like previous Judges, the 1971 edition featured specific stripes and callout decals, a blacked-out grille, functional Ram Air with semigloss-black hoodscoop openings, a Judge badge on the glovebox door, and Rally II wheels without trim rings. Updates unique to it included the 455 H.O. callouts on the sides of the rear wing, G70-14 fiberglass-belted tires, and optional Honeycomb wheels.

The most significant mechanical change made to the 1971 Judge was the deletion of 400ci engines from the parts list. In their place, the top-of-the-line 455 H.O. was standard, and there were no other engine offered.

Unfortunately, The Judge's popularity with new-car buyers dropped off dramatically, and the option was dropped in February 1971. All told, just 374 were built, including a scant 17 convertibles. Unpopular when new, they are now highly sought-after and valuable collectibles today.

The GT-37

The GT-37 returned for 1971 with the same basic standard equipment as the year before, though it was now available in the hardtop bodystyle only. (Its new Sport Mirrors interfered with the operation of the pillared coupe's wing windows.) As was the case in 1970, the base engine was a Pontiac 350/two-barrel, hooked to a three-speed manual transmission.

For options, the low-performance 400/two-barrel was retained. A 300hp 400, a 325hp D-port 455, and the 335hp 455 H.O. were optional. Other items, which were standard or optional on the GTO, such as the heavy-duty frame and performance-oriented gear ratios, could be ordered.

A midyear change in the graphics package saw the deletion of Judge-style stripes in favor of a spear-shaped, body-length, reflective stripe decal that included a clear cutout in the vinyl that spelled out a body-colored GT-37. Cars with that stripe are referred to as 1971½ GT-37s. Production totals for 1971 and 1971½ GT-37s stood at 5,802 units.


You really have to hand it to Pontiac engineers. They were fighting an uphill battle to maintain the GTO's performance standards, and considering the forces working against them, they did an admirable job. As already stated, they released the 455 H.O., the most powerful engine ever bolted into a production GTO, and juggled the available axle ratios on the lesser-engined models to maintain the acceleration buyers were accustomed to from the original muscle car.

Motor Trend tested a 1971 455 H.O. GTO with a four-speed transmission and 3.90 gears, and produced a 6.1-second 0-60–mph time, with a 13.4-second quarter-mile time at 102 mph. This stacked up very favorably against the previous Ram Air IV cars, and best of all it was a regular production car and not a performance-tuned Royal Bobcat conversion. (Royal Pontiac sold its Royal Racing Team in 1970.)

Hot Rod tested a 1971 GT-37 with the 300hp 400-four-barrel hooked to a four-speed and 3.55 gears. With a 3,675-pound curb weight, BFGoodrich G70-14 tires, and the air-cleaner removed, the GT-37 ran a best of 14.40 seconds at 97.50 mph, which was right in the ballpark for previous model-year GTOs.


With the tide turned against performance, GTO advertising ground to a near halt. Ads for the GT-37 were more prominent, as the market for a more insurance-friendly, but still sporty mid-sized cars was still there.

What was the message from Pontiac in its print ads for the GT-37? “There's a little GTO in every GT-37. And you don't have to be over 30 to afford it!”

As one would expect, most of the 5,802 GT-37s built that year were 350ci-powered machines—5,015 to be exact.

Production Figures

Pontiac built 10,532 GTOs in 1971, including 661 convertibles. The aforementioned Judge production figures are included in the total. GT-37 production totals are not included, as they were not technically in the GTO series.

The 1971 model year was a year of lasts—the last Judge, the last GTO convertible, the last GT-37, and sadly, the last year that the GTO was a separate series. The GTO would return for 1972 but only as a LeMans option package. The GTO's days were numbered and the clock was ticking.