Information and specs for the Pontiac 421 V8 engine. The 421 SD Tri-Power engine offered during these years produced the highest horsepower of any motor in the Pontiac V8 lineup at 376 bhp. For 1965, however, the 2+2 became a bonafide muscle car. Pontiac Engine Torque Specifications. Beginning in 1967 casting numbers moved to the rear of the block just behind cylinder #8. It was rated at 366bhp (273kW) (gross) in the GTO version. The camshaft was also revised to have a slightly higher duration, the carburettor jets tuned and a dual exhaust was implemented allowing the power to increase to 220hp (223PS; 164kW) at 4000 rpm and 320lbft (434Nm) of torque at 2800 rpm. If you would like to change your settings or withdraw consent at any time, the link to do so is in our privacy policy accessible from our home page.. According to the June 2019 issue of Muscle car Review magazine, during dyno testing performed during that era, the National Hot Rod Association (NHRA) rated this Pontiac W72 400 T/A 6.6 engine at 260 to 280 net horsepower instead of the 220-hp rating published by Pontiac. On the invoicing for the 1979 model year Firebirds, they had the option listed as L78, however, every 1979 400 equipped car received a W72 engine. The 428 was factory installed in large cars only. Cam choice is always extremely important, and Jim decided to go with an aggressive Crower mechanical flat-tappet stick with 247/252-degrees duration at 0.050 and 0.515/0.525 lift (0.495/0.505 with 0.020 lash) with 1.6:1 rockers. RamAir 4 Motor Price $15500.00. For 1959 the V8's stroke was increased to 3+34in (95.3mm), raising displacement to 389cuin (6.4L). Compression jumped from 11.0:1 to 12.0:1, while other tweaks increased maximum shift points by 500 rpm, to a screaming 6400 rpm. Even more powerful were the 421 Super Duty V8s that could produce up to 410 horsepower. The code consists of 3 or 4 digits. After the 1974 SD455 was dropped the 1975 Firebird's top performance engine was an 'L78' Pontiac 400cuin (6.6L). The goal of making a Pontiac Hemi succeeded but the engine was never produced. And it cruised silently and rode with less harshness than muscle intermediates. It was implemented as further development of a cost-effective, more fuel efficient V8 derivative of the 301 V8 for the CAFE requirements. The engines feature a cast-iron block and head and two valves per cylinder. 1963 Pontiac V8 Engine Specs. On premium fuel, it was rated at 207 hp at 5200 rpm and . This was the beginning of factory supplied performance items such as 4 bolt main bearings and windage trays to reduce friction from crankcase oil. The 455 HO package was only available to late model year Pontiac Firebird Trans Am's, and was mandatory with a 4-speed transmission. Simply put, what good is the power if the engine does not last? This may have been propagated by the only authorized company that is licensed to reproduce these decals not including the "6.6 LITRE" in the Trans Am decal kits, and only including "T/A 6.6" with no extra cost. Horsepower: See Part 2 In the early '60s, the engine program at the Pontiac division of General Motors was a wide-open operation that bustled with innovation. It was the same engine as the '67-'68 400 HO[18] but for 1969 and 1970 it included a driver-selectable outside air induction system on the GTO(it was a separate option on Firebird), with the hood vents opened and closed using a knob located under the dash, below and to the right of the steering wheel, its bracket labeled "RAM AIR". Required airflow at 28 in/H2O = HP/ # of cylinders/0.257 We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development. The earlier 1975-78 blocks had metal shaved from the journals and bottom end as well as a decrease in the nickel content of the block in an attempt to decrease the overall weight of the vehicle to help alleviate emissions and cost. From 1955 through 1959, the Pontiac V8 was also used in some GMC pick-up trucks. . This installment includes the assembly and parts selection up to the long-block. In 1964 when the new "A" body intermediates came out there was a new corporate (GM) engine size limitation to anything less than 330cuin (5.4L). These are general guidelines. [citation needed]. Cougar pulled out of Mustang's shadow with the striped and spoilered 1969 Mercury Cougar Eliminator. From a performance perspective, the 2+2 is pretty impressive. A mere five were built, all with a four-speed transmission. "1966 Pontiac 2+2" A set of Hooker Super Comp headers will be used on the dyno, and Jim is porting the stock heads to increase intake-port flow by 30 cfm. The XS-code 389 was still rated at 360bhp at 5,200 rpm, same as the more common WS-coded Tri-Power 389, but performance was noticeably improved on acceleration runs. Jets, Primary: Center #64 adjust power valvespring for 12 Hg at 1,000 rpm Valves: Competition Products stainless steel, 1.92 /1.66-in While production of 196970 A-body Ram Air IV cars was low at just 1563 units(759 1969 GTOs including 302 Judges, and 804 1970 GTOs including 397 Judges) 1969 and 1970 model year F-body Ram Air IV cars were even rarer at just 245 total units produced. 068) to 301/313 (No. See profiles, photos, and specifications of, Muscle cars came in many shapes and sizes. The base engine was the 421 four-barrel with 338 horsepower. Pistons: Icon PN IC892 application 428 +0.030-in with 10cc dish The inlets were all well within the boundary layer that exists close to the surface, so all of these systems would more accurately be described as "outside air induction" systems, benefiting from the intake of cooler, and thus denser, outside air versus the comparatively hotter and less dense air under the car's hood. Valvesprings: Crower, dual no damper Distributor: '61 Delco cast-iron with direct oiling designs, the SD-455 was a much improved engine. When Robert Critchfield took over as general manager in 1952, he launched an ambitious plan to move Pontiac into the upscale, mid-range market occupied by Oldsmobile, and that demanded V8 power. A limited-slip differential and gearing up to 4:11.1 were optional. Standard ratio with the 400 was 3.55:1(except 3.36:1 in Firebird for 1969) regardless of transmission(3.23:1 for cars with air conditioning). This is it! By early 1979, orders for the W72 package were being rejected by dealers as they supply had run dry. . It shared the 389's 3+34in (95.3mm) stroke, but its bore was 3.78in (96.0mm) for a displacement of 336.66cuin (5.5L). Pontiac introduced the OHC 6 in two flavors for '66: a base engine with a one-barrel carburetor that developed 165 hp at 4700 rpm, and a sportier version with a 10.5:1 compression ratio, a high-lift cam, a split exhaust manifold, and GM's new four-barrel Quadrajet carburetor (below). Valve guides: K-Line, liners To view the purposes they believe they have legitimate interest for, or to object to this data processing use the vendor list link below. In light of this, the 'Year' entry, as indicated by the chart below, may actually represent the year that the heads were cast, versus the year that they were actually installed on an automobile. Both Randy and Stan were aware of the . - P.B. Optional power was the 421/356 with Tri-Power or the 421 HO putting out 376 horses with Tri-Power. What was most interesting about the 421 engine in the beginning was that it was a dealer installed option only known as the SD (Super Duty) 421. More 400cuin (6.6L) engines were produced by Pontiac than the other versions - estimates range from 80 to 200 units. . Torque: See Part 2 [8] All of these improvements provided the W72 with a power rating of 200hp (203PS; 149kW) at 3600 rpm and 325lbft (441Nm) of torque at 2400 rpm, while the standard L78 400 only produced 180hp (182PS; 134kW) at 3600 rpm and 325lbft (441Nm) of torque at 1600 rpm. He wanted to confirm his parts are up to the task of holding the cylinder pressure that creates horsepower. Instead, they were substituted with the L80 Oldsmobile 403, or the L37 Pontiac 301 if they still requested a 4-speed transmission. Preparation: File-fit for end gap if needed, wash Though a change of camshaft would delay production, Pontiac decided to change camshaft, employing one with identical timing to the 744 camshaft, which had been used in the 400 Ram Air(aka Ram Air III) engine with manual transmissions. The Pontiac 2+2 is a full size automobile that was manufactured by Pontiac, built on the B-body chassis.It debuted for the 1964 model year as a trim-only option for the Pontiac Catalina, with special door panels, bucket seats with a center console, and exterior badging.Pontiac marketed the 2+2 as the "big brother" to the popular Pontiac GTO.. Beginning in 1965 the name Catalina was no longer . The 326 subsequently became the optional V8 engine for Tempests, and later the Pontiac Firebird, through 1967 and maintained the 17 degree cylinder head valve angle for its entire production run. Only about 2000 like this one were built with 4 speed Muncie transmissions. Stock Pontiac Engine Specs. Jim Taylor knows this, so he took a mathematical engineering-style approach to finding 100 hp in a relatively optimized engine. Pontiac V8 Engine Tune Up Specifications. . Some of our partners may process your data as a part of their legitimate business interest without asking for consent. Though never factory-installed in any car, the ultimate engine of the Ram Air line of engines was the tunnel-port Ram Air V. In 1969 Pontiac created four versions of the Ram Air V engine: a 303cuin (5.0L) short deck version for SCCA Trans-Am racing, a 366cuin (6.0L) variant for NASCAR, a 400cuin (6.6L) version for street use in GTOs and Firebirds, as well as a 428cuin (7.0L) adaptation for drag racing. It was the top-of-the-line engine unless one opted for the "Ram Air" V-8 derived from it. In 1969, Pontiac unveiled its Trans Am model Firebird, and since racing rules required engines of less than 5L (305.1cuin), Pontiac unveiled the 303 for racing models only, never available to the public. The crankshafts were also unique in the fact that they featured only two counter weights instead of the usual five and also featured lightened connecting rod journals. "Armasteel" was a trademark of pearlitic malleable iron developed by GM's Saginaw Metal Casting Operations around 1936, which was referred to as "locking ball" cast-iron, as opposed to the "flaking" type found in other engines. Given that, it was no accident that the leader in intermediate muscle also put together the finest full-size performance machine -- the 1966 Pontiac 2+2. From 1977 to 1981 there were 4 distinct 301 versions: For 1981 model year vehicles, the engine codes are the 8th digit of the VIN. Also, a rumored 75 cars were built with non-Super Duty 421 engines rated at 320 bhp. Pontiac Heads; Pontiac Engine Torque Specs; Pontiac Cars (Body Types) Pontiac Engine Information; Instruction Sheets; Compression Calculator; Ask a Tech Question; Customer Service. Pontiac continued using its round-port cylinder-head design for 1971-'72 on the 455 HO. The "455 HO" moniker took on a whole new meaning with the introduction of the 1971 model year; Intended as a low compression progression from the previous years Ram Air IV engine, all 1971 455 HO engines used a heavy duty 4 bolt main block, round port cylinder heads (casting #197; with 8.4: compression), "Ram Air" style exhaust manifolds, and a two-part aluminum intake manifold. gasoline (petrol) engine with displacement: 6902 cm3 / 421.2 cui, advertised power: 252 kW / 338 hp / 343 PS ( SAE gross . Whether all were installed in GTOs is unknown. Pontiac had prepared for the forthcoming cancellation of the venerable 400 by producing large volumes of the stronger cast "XX" 400 blocks in 1977 that were assembled in 1978, and stockpiled at a warehouse by the assembly plant for later use. Made with a provision for dry sump oiling, it truly was a racing engine, detuned for use in passenger cars. Initial advance: 18-deg The new-for-1965 "Venturi" body shape and curved side glass were carried over with updates front and rear. 1966 Pontiac Catalina Specifications and Production. The heart of the build, a code 45B 1964 421 HO 370 HP manual trans 4-bolt main block, all Pontiac 421 engines without exception had 4-bolt main caps. It was rated at 360hp @4300 RPM in the GTO and 370 @ 4600 RPM in the Grand Prix and other full-size Pontiacs. PONTIAC : 1965-75Tune-up Specifications : Year: Engine Car Model: Spark Plug Type (AC) - Gap: Point Gap: Dwell Angle: . Update your shipping location. According to GM mandates horsepower was now rated in net figures as opposed to gross, so on paper the 1972 455 HO appeared to have a significant drop in power, but in fact it was very much the same engine, and performance figures reveal this to be true. Pontiac Engine Torque Specs Pontiac Engine Torque Specs. This included the ESC (Electronic Spark Control) distributor and controller borrowed from the 301 Turbo, which allowed for higher timing without the penalty of engine damaging pinging or preignition. This was to ensure there was enough fuel to cool the cast offset dished pistons. A larger 4in (101.6mm) ram air flex duct to the air cleaner from the left-hand fender, specific carburettor calibration for the Rochester Quadrajet, a "T/A 4.9" callout on the shaker, 60 psi oil pump, and cam similar in grind to the 220hp (164kW) 400 from the 19781979 model year were also included. Styling for Status. Regarding Crower's upgrade suggestions for its . With a view to the latter, what we find lurking under the hood is the 421ci Tri-Power V8. Lifters: Crower solid with EDM oil hole (0.024 inch) Pontiac V8 Engine Codes and Specifications. Idel RPM Automatic In Drive Notes; 326: 1964: 45S: 0.035: . Type Size Carb Horse Power Tourqe; Tri-Power: 389ci: 3x2bbl: 360 hp @ 5200 rpm: 424 lb-ft @ 3600 rpm: Base 8 . Paul Stenquist. Muscle cars wouldn't have much muscle without horsepower -- but what exactly is horsepower? Setting initial timing at idle with the vacuum advance disconnected will usually fall around 12 to 16 degrees, but that's not really important. Laconic would be one way to describe this Pontiac's eBay listing, all it states is, "1966 Pontiac Ventura, 421 Tri-Power, 4 speed Runs/ Drives Great, Very Clean - Garage Kept".OK then, now you know what I know. The 1969 HO 350 HO was equipped with the 400cuin (6.6L)'s large valve heads (# 48's) and the 400 HO camshaft and rated at 330hp (246kW). They acquired the featured Montero Red 1966 Pontiac Catalina post car, which was equipped from the factory with the 421 H.O. Beginning in 1967 casting nnumbers moved to the rear of the block just behind cylinder #8 . Carb: (3) Rochester two-barrels PMD Based on the same short-deck as the 301, the "LS5" 265.1cuin (4.3L) was offered only in 1980 and 1981. However, the 1959 389 engines had the generator in front of the heads with reverse flow cooling still in use. $6.49 shipping. Read. Here is another number to ponder: 370 hp. moniker from the shaker due to the disappointing public approval as the motor was not deemed to be "High Output". It could only be ordered with a TH200 automatic transmission and a 2bbl configuration. However, in the June 1974 issue of SUPER STOCK AND DRAG ILLUSTRATED, a new 1974 Trans Am with the SD-455 motor ran 14.25 @ 101mph (163km/h). Again, its bore was expanded, this time 0.03in (0.76mm) to 4.1525in (105.47mm). By 1963, the more powerful Pontiac 421 was beginning to outshine the 389 for performance applications. Kits for Pontiac applications. Maximum RPM (high-RPM engine): over 8000 rpm, Engine weight: estimated 550lb (249kg) complete, Power: estimated 640hp (477kW) at 7500rpm, This page was last edited on 30 January 2023, at 13:15. The valve angle was reduced from 17 degrees to 14 degrees for better breathing. The W72 Performance Package also included an upgrade to the rear differential ratio, setting the rear gear ratio to 3.23 for all 1977 and 1979 W72 Firebirds, with the exception being 3.42 for 4-speed equipped W72 Firebirds in 1978 only. The 1966 Pontiac Ventura doesn't necessarily come up when speaking of 60's muscle cars, but the type of V-8's offered with the Ventura meant plenty of power. Pontiac Heads; Pontiac Engine Torque Specs; Pontiac Cars (Body Types) Pontiac Engine Information; Instruction Sheets; Compression Calculator; Ask a Tech Question; Customer Service. Pontiac went to open-chambered heads in some 1967 models and all 68 and up to improve power, engine breathing and reduce emissions. Engine block and cylinder heads were cast at Saginaw Metal Casting Operations then assembled at Tonawanda Engine before delivery to Pontiac Assembly for installation. For those who may not be familiar with the equation, here it is again: It remained on the same platform, but for the 1966 models, it became a different Pontiac series. The piston weighs 630 grams with the pin versus the stock piston and pin weight of 790 grams. The results showed Pontiac that an L-head simply couldn't compete with an overhead valve engine. The 421.19cuin (6.9L) was introduced in 1961 as a dealer-installed Super Duty option. The Pontiac V8 engine is a family of overhead valve 90 V8 engines manufactured by the Pontiac Division of General Motors Corporation between 1955 and 1981. Perhaps the most unusual variation of the Pontiac V8 was the 1961-63 Trophy 4, which was a 45-degree inclined 194.43cuin (3.2L) inline-4 created from the right bank of the 389 for the debut of the Tempest. Piston-to-deck height: 0.009-in Additionally, the 301 W72 never received the option to come equipped with a manual transmission like the standard 301 received in 1979, and disappointingly, production for all Pontiac V8's ended soon after as GM sought to "corporatize" engine production. For the truly obsessed, 16 Grand Prixs were built with Pontiac's 421 Super Duty engines, rated at a staggering 370 bhp. The engine was available in all full-size Pontiacs. By 1963 Pontiac decided it was time to release the 421 V8 officially to the general public and the motor would continue to be available until the end of the 1966 model year. It featured the "744" 301/313 camshaft, which offered more duration and overlap than the "HO". . Ellingson Motorcars (877) 638-7170. Prices ranged from $2,760 to $3,220 . - P.Top - Correct Exterior/Interior. Model Number: Body/Style Number: Body Type & Seating: Factory Price: . The 301 Turbo was unique since it had a beefier block than the 197779 versions (which carried on in the non-turbo versions in 1980 and 1981), a very mild camshaft with 0.35in (8.9mm) lift and 250 degrees gross duration, a 60psi (4.1bar) oil pump to ensure adequate oil to the oil-cooled Garrett TBO-305 Turbocharger, a rolled fillet crankshaft, a fully baffled oil pan, and a specific 800cuft/min (23m3/min) Quadrajet carburetor. It is a known fact that a person's pupils dilate slightly when viewing something pleasant to the eyes. In 1968, a 320hp (239kW) HO option was offered in the Tempest and Firebird. Standard motor was the 421 4 barrel with 342 horsepower, which was no slouch itself. In 1969, Pontiac also used a revised crankshaft out of a Pearlitic malleable-iron, although it still used the "N" casting letter. . Math, not gasoline, makes horsepower under the hood of a Pontiac. Greater throughput mixed with the proper amount of fuel and ignited at the ideal time for the flame to expand against the piston will result in more power. The engine was dubbed the TEMPEST V-8, a nickname it retained until the end of 1960. Only about 400 were produced before the fuel injection system was quietly dropped. Preparation: Magnaflux, check for equal stroke and index, grind, polish 0.010-in NASCAR race cars embody the muscle car philosophy of power. Standard in the Firebird Trans Am, it was still a rare engine. It included a new camshaft with duration increased from 288/302 (No. Manage Settings It produced 120hp (89kW) After 1981, the Pontiac V8 was replaced entirely by the GM "corporate" V8's from Chevrolet and Oldsmobile. A common misconception made by enthusiasts was the notion that all Pontiac engine equipped Trans Ams featured the "T/A 6.6" decal on the shaker, however, it was exclusive to the W72 engine that was featured on less than half of all Trans Ams made during this period. The compression ratio will be 10.6:1. Final torque ratings may vary and need to be determined based on application and parts used. For 1958 the V8's bore was increased again to 4+116in (103.2mm), increasing displacement to 369.4cuin (6.1L). Note the tri-color Pontiac Ventura upholstery. 1966 Pontiac Catalina Size cfm: Total flow, 1,050 cfm The valve size increased as well, to 2.11in (53.6mm) intake and 1.77in (45.0mm) exhaust valves on high-performance heads. However, the RA II was limited to a 1.50:1 rocker ratio, while the RA IV used a 1.65:1 ratio, which yielded significantly greater total lift and, therefore, superior flow and power. Often called the "Ram Air III", this engine was officially called the "400 Ram Air" for 1969 and then simply "Ram Air" for the 1970 model year. . Today, they have an average value of $430,000 in #3 (Good) condition, while the best in the world is worth about $550,000. Bearings: Sealed-Power mains and rods, cam Dura-Bond The standard head seen on an L78 400 Pontiac was the low compression 6x8 head, while the 6x4 head seen on the W72 had hardened valve seats for a higher RPM operating range, improved air flow, and higher compression. The 455 was used through 1976 when it, as with many other large displacement engines, was discontinued as manufacturers moved to smaller, more efficient models, even in their full size car lines. Pontiac in the 1950s was one of a few US manufacturers that did not regularly identify their engine names and sizes with air-cleaner or valve-cover decals. Engine Oil: 95 ft-lbs. or Best Offer. Primary tube diameter: 1.75-in Beginning in 1961 the Pontiac V-8 (389 and 421) was dubbed the Trophy V-8, due to its many victories in racing. The 287 was an "oversquare" engine with a bore and stroke of 3+34in 3+14in (95.3mm 82.6mm), for a total displacement of 287.2cuin (4.7L). Flamboyantly styled and expansively proportioned, the 2+2 was unbeatable for sheer presence. The 1958 370" engine and the 195960 389 version was named the "Tempest" V-8 and changed in 61 to the "Trophy" V8. 1965-75 Pontiac & Tempest engine tune-upspecifications including timing, dwell angle, and Spark Plug Gap, and firing order. The horsepower ratings of this era were often dubious, with engines rated higher or lower in output for advertising, political, or insurance purposes. Preparation: Disassemble, check ball seat for width, spring tension, plate clearanceHEADS Spiral clip 301 2-barrel (135hp, 101kW), (5th character of the, 301 4-barrel (150hp, 112kW), (5th character of the. Engine Block Date Code. This money bought a potent 389 V-8 with 267-283 bhp . A camshaft with 301/313 degrees of advertised duration, 0.407-inch (10.3mm) net valve lift, and 76 degrees of valve overlap was specified for actual production engines in lieu of the significantly more aggressive Ram Air IV-spec camshaft that had originally been planned for the engine (initially rated at 310hp (231kW) with that cam), but ultimately proved incapable of meeting the tightening emissions standards of the era with sufficient margin to satisfy Pontiac emission engineers given expected volume production variations. For 1970 the Trans Am was the only Firebird available with the Ram Air IV, and 88 were produced during the abbreviated 1970 F-body production run. gasoline (petrol) engine with displacement: 6902 cm3 / 421.2 cui, advertised power: 252 kW / 338 hp / 343 PS . The 400 remained in production through the 1978 model year, with 1979 cars receiving engines produced the previous year. For the 1969 and 1970 model years it was the standard engine in both the Firebird Trans Am and the GTO Judge. release the 421 V8 officially to the general public and the motor would continue to be available until the end of the 1966 model year. The company says engines running this cam benefit from headers, cylinder-head port work, a large-cfm carb, and an ignition upgrade. Along with proper parts selection, accurate machining and assembly are also important. The basic package included the heavy-duty suspension, with even stiffer springs and shocks available. Once corrected the SD-455 was recertified and was released for production in late April 1973. Standard only for the Pontiac Bonneville was Pontiac's first-ever fuel injection system. The 2-barrel version was last offered in 1979. Stating in 1962 the "421" and the "421 SD" engine became available as a factory option until 1966. A higher-output version was offered, called the 326 HO (High Output). The shaker wore the decals "455 H.O." The 1981 301 Turbo gained the electronic controls with an O2 sensor, feedback ECM and E4ME Quadrajet providing a slight reduction in output to 205hp (153kW) and 340lbft (461Nm).The 301 Turbo was limited to Trans Am and Formula Firebird production only. 1965 Pontiac LeMans GTO Mecum. The 421 SD produced up . Pontiac listed the 290hp (216kW) rating at 4000 rpm for a motor that had a 5700rpm redline on the factory tachometer. Free local pickup. Duration at .050: 247/252-deg Now select an engine model (if applicable) -- Pontiac Engine Models -- All Pontiac Kits 151 301 326 350 3800 389 4-cylinder 400 421 428 455 Brodix Heads Edelbrock Heads Iron Duke L67 Pro Stock Dart Heads Pro Stock Heads Ram Air Runner Heads Super Duty Generic V8. Preparation: Wash after balance for assembly 1966 Pontiac Catalina . Bore and stroke were 4.121in 2.84in (104.7mm 72.1mm) 303.63cuin (4,976cc). The W72 package was a standalone option, and although was discounted when ordered in conjunction with the Y82/Y84/Y88 Special Appearance package, did not come included with Special Edition Trans Ams, it remained an extra cost option. The 303 had shorter connecting rods, smaller 2.5in (64mm) journals and a solid lifter version of the Ram Air IV camshaft. When fitted with other high-airflow components, it produced a good balance of low-end torque and higher-RPM power. While the 400 offered excellent power in the GTO (360 horses and 445 lb-ft of torque in 1968), Pontiac turned to what it called 'big journal' engines for the muscle machine's next upgrade. Some production test cars ran considerably slower and yielded 14-mile (402m) times in the 14.5 second/98mph (158km/h) range in showroom tune (uncited sources)- results that are quite consistent for a car with a curb weight of 3,850 pounds (1,746kg) and the rated 290hp (216kW) SAE NET figure that some sources suggest was "under-rated." The SD-455 motor was listed as an option in dealer brochures for the 1973 Grand Am and LeMans GTO(and planned for the Grand Prix as well) although none were produced for sale.