Production Color & Trim Engines KwikSpecs

Looking from the outside, you'd be hard pressed to tell the '71 from the '70, as the visual pontiac.com clues are minor. The one visual clue is the soon to be trademark of a Trans Am- lettering the engine displacement on the shaker. Perhaps Pontiac wanted to let everyone know there was a new and torqueier engine residing beneath the shaker.

Nineteen-Seventy-One marks the year in which the engine most associated with the Trans Am made it's debut. The 455. This new engine was the 400 stroked .46 inches (to 4.21 vs 3.75 inches) and offered a bit for more torque - 480 gross lb/ft of torque to be exact. To be more exact, the new net torque ratings were 410 lb/ft @ 3600 prm. The increase meant the engine was now "undersquare" , meaning the stroke was longer than the diameter of the 1981 cylinder bore (4.12"), henceforth a 5500 rpm redline. The engine, coded as YE or YA when coupled to an automatic and WL or WC when installed in front of a 4-speed, featured a four-bolt main bearing block and aluminum intake manifold.The new engine was not without compromise, however, as the horsepower numbers dropped off a bit as compression ratios took the first plunge into mediocrity. In 1970 the 400 V8 featured a 10.5:1 compression ratio, while for '71 the ratio dropped to 8.4 as the auto makers were succumbing to the pressures of the insurance companies and preparing for the inevitable switch to unleaded fuels.

Since the 455 was an undersquare engine, Pontiac engineers used lighter parts in the reciporcating assembly to reduce mass, therefore relieving stress. Each piston lost 1 1/2 oz each to reduce the mass. To make the engine stronger, the crankshaft main bearing journal diameter went from 3.00" in the 400 to 3.25" in the 455. All crankshafts were cast of nodular iron rather than standard cast iron for increased toughness.

No longer were there any "ram air" references, as this engine performed it's last service of duty the prior year. On the bright side, the 455 posted good horsepower numbers, still producing KwikSpecs 335 gross hp at 4800 rpm or 310 net @4800 and the aforementioned 480 lb/ft of torque at 3600 rpm. A new cylinder head casting, #197 replace the mighty "Ram Air III and IV" cylinder heads. The head was unique to the 335 hp engine, as the "other" 455 engines had the #66 casting. The camshaft lost a great deal of lift in the 400 to 455 switchover. On the Ram Air IV 370hp engine, the valve lift for the intake/exhaust valves were .527/.527 inches respectively. The 455 used the part number 9779068 camshaft, the same as the R/A III, and it developed .408/.406 inches of lift respectively. Also missing was 20-degrees of intake and 18-degrees of exhaust valve duration. On the plus side, the 455 H.O. in the Trans Am still reatined screw-in rocker arm studs.

Atop the engine sat a cast aluminum intake manifold with a separate cast iron crossover for exhaust gases recirculation. By making this a separate piece, it didn't take owners long to remove this as to increase power. A Rochester Quadrajet 4-bbl carburetor sat below the shaker/air cleaner assembly.

The H.O. engines still had the desirable "round" exhaust port rather than the "D" shaped ports of mainstream 455's. Another desirable quality of the 455 H.O. engines was the select fit porcess during line assembly of the engines. This allowed for closer tolerances resulting in a nearly blueprinted engine - direct from the factory.

A conventional distributor was still used, and it carried pn 1112073 and ignited AC R-46S spark plugs set at .035"

Three transmissions were offered, the standard M13 three speed HD manual, the RPO M40 TurboHydraMatic 400, or the close ratio four speed manual RPO M22 rock crusher transmissions. The gearboxes were ideally matched for the generous levles of torque the 455 could supply. At the rear of the car, the famed GM 12-bolt rear end was no more, replaced by a bit less sturdy 10-bolt. Three axle ratios, 3.08, 3.42, and 3.73:1 were offered, depending on transmission and equipment choices.

The shaker scoop was still functional as the exterior engine noise level standards hadn't legistated this neat feature out of production. As on the '70 models, the solenoid activated flapper and this was still an axiliary source of cooler air as the air cleaner ingested air normally through dual snorkels.

The rest of the outside was carryover for the most part. Color choices were still limited to cameo white with blue stripes and shaker or the lucerne blue with a white stripe/shaker combo. The engine displacement decal were the same color as the exterior. The poly cast honeycomb wheels made their debut in '71 and would remain popular until replaced by the aluminum snowflake of 1977. These wheels were quite deceptive as they certainly had the look of a "mag" wheel. Nothing could be further from the truth however, as these wheels were merely steel 15" x 7" steel wheels with a ruberized metallic silver honeycomb center (the first composite wheel?).

Inside, the T/A received the high-back bucket seats. These seats would remain in basic form until the advent of the all-new 1982 models. The only other seat style offered during the 71-81 production run were the Recaro buckets offered in the '81 NASCAR edition. The high back style if the seats were very much in vogue in the early seventies. They gave a wrap around feel to the interior, while being somewhat comfortable.

Somewhat is stressed because for some reason, Detroit had a problem with building cars with adjustable seat backs. (the Chevrolet Camaro did have an optional two-position seat back adjuster). The seat was very upright, but this was almost necessary with the formula steering wheel. Matching up to the front seat center console was a rear seat console which extened from the rear of the front one and filled in the otherwise carpeted void of the rear seats. Pontiac introduced an option that proved to be ahead of it's time, a cassette tape player. In a world where the 8-track was king, the cassette player was a much undesired option. I personally have never seen one in a Trans Am (or Firebird), and my guess is this would be a rare piece. Another new option, an in car rechargable flash light could be had for a mere $12.64.

The base price increased to $4595.00, a $290.00 increase over the 1970 version. Production of the Trans Am dropped to a mere 2116 cars, nearly a 50% decrease form the 3196 1970 models built. Automatic's outnumbered manuals 3-to-2 with 1231 buyers opting for the turbo 400, and 885 going for the "rock crusher"

1971 was certainly a pivotal year to the Trans Am, with legislators pushing for clean air and less horsepower, many feared the newly designed Firebird and specificly the Trans Am would be a short lived "nice try".


Back to 1970 Back to Introduction Forward to 1971

1971 Trans Am Production

Engine

Code

Trans

Production

Total

455 H.O.WL, WC4M885
455 H.O.YE, YA3A1,231

2,116

Color & Trim Codes
Exterior ColorsCodeInterior ColorsStd Trim CodeCustom TrimCode
Cameo White
11
Blue Vinyl201 Vinyl211
Lucerne Blue
26
Ivory Vinyl212
SaddleVinyl203Vinyl213
SiennaVinyl214
JadeVinyl206Vinyl 216
SandalwoodVinyl207Vinyl 217
Cloth &Vinyl 227
BlackVinyl209Vinyl 219
Cloth & Vinyl 229

Engines

Gross Figures

CID-Version

Code

Trans

HP@RPM

Torque@RPM

455 HO

Wl, WC

4M

335@4800

480@3600

455 HO

YE, YA

3A

335@4800

480@3600

Net Figures

CID-Version

Code

Trans

HP@RPM

Torque@RPM

455 HO

Wl, WC

4M

310@4800

410@3600

455 HO

YE, YA

3A

310@4800

410@3600

Transmissions

RPO

Speeds

Code

Usage

M13

3-Manual, HD

RM

Std

M22

4-Manual, Close Ratio

WO

Opt

M40

3-Auto

PQ

Opt

Rear Axle Ratio & Useage

Code

Useage

Ratio

GYG

Std w/Auto Trans w/ Air Cond

3.08

CJG

Std w/Man Trans or Auto Trans/no air cond

3.42

CGG

Opt. Man Trans w/o Air Cond

3.73


Back to 1970 Back to Introduction Forward to 1971


Year Selector

Introduction

1970 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981

Additional links:
Return to 2nd gen. Trans Am home page
A look back at the 1970 Trans Am
1972 - The Lean Year
1973 - SD-455 and the screamin' chicken
1974 - Good Times...Bad Times
1975 - Soul Survivor
1976 - Spirit of '76
1977 - Year of the bandit
1978 - Horsepower and Handling
1979 - "It will not pass this way again"
Return to Gary Lisk home page

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