History
Pre-development
Pontiac began as a "companion make" to the Oakland division of the General Motors line of automobiles in 1926. Pontiac successfully competed against more-expensive inline four-cylinder models with their inline flathead six-cylinder engines. After outselling Oakland, Pontiac became the sole survivor of the two by 1932. In addition to the inline 6, Pontiac used the Oakland V8 for one year, 1932, debuting theDevelopment
By 1949 work on a OHV V8 had begun, but moved along slowly. When Robert Critchfield took over as general manager in 1952, he launched an ambitious plan to move Pontiac into the upscale, mid-rangeDesign
The 1955-up Pontiac V8 that finally reached the public was an overhead valve engine withSmall-journal engines:1955-1981
287
The V8 engine was introduced for the 1955 model year as the "Strato Streak". Not long before the model year introduction, Pontiac management decided that the entire line would be V8-powered. This was based on results of over 1 million test miles, which was unheard of at the time. The 287 was an "oversquare" engine with a bore and stroke of , for a total displacement of . Compression ratio was a modest 8.00:1, with valve diameters of (intake) and (exhaust). It was rated @ 4600 rpm and @ 2400 rpm with a two-barrel carburetor, @ 4600 rpm and @ 2800 rpm with the four-barrel carburetor.317
For 1956 the V8 was bored out to , increasing displacement to . It was offered in the following forms: (with347
For 1957 the V8's stroke was increased to , for a displacement of . For the first time, Pontiac offered Tri-Power, three two-barrel carburetors with a sequential linkage (replacing the previous dual-quad set-up). Power ratings increased accordingly: (with manual transmission) * Two-barrel carburetor, 8.5:1 compression, @ 4600 rpm, @ 2300 rpm * Four-barrel carburetor, 10:1 compression, @ 4800 rpm, @ 2600 rpm (with Hydramatic) * Two-barrel carburetor, 10.0:1 compression, @ 4800 rpm, @ 2600 rpm * Four-barrel carburetor, 10.25:1 compression, @ 4800 rpm, @ 2900 rpm * Three two-barrel carburetors, 10.75:1 compression, @ 5000 rpm, @ 2800 rpm. Several dealer-installed camshafts were optional to increase power further to . which was seen on the hood of the 1957 Daytona Grand National winning car driven by Cotton Owens. Standard only for the370
For 1958 the V8's bore was increased again to , increasing displacement to . The engine was dubbed the TEMPEST V-8, a nickname it retained until the end of 1960. The fuel-injected engine became an option on any Pontiac model, carrying a staggering price tag of $500 (almost 15% of the car's base price). It was rated at @ 4800 rpm and @ 3,000 rpm on 10.5:1 compression. Only about 400 were produced before the fuel injection system was quietly dropped.389
For 1959 the V8's stroke was increased to , raising displacement to . This was the beginning of factory supplied performance items such as 4 boltTrophy 4
Perhaps the most unusual variation of the Pontiac V8 was the 1961-63 '' Trophy 4'', which was a 45-degree inclined326/336
In 1963 Pontiac dropped the Buick division built 215 cu. in. aluminum V8 it had offered in the400
For 1967, Pontiac retired the and replaced it with the 400 cu in (), a 389 bored-out by + to a bore and stroke of . The 400 remained in production through the 1978350
In 1968 the 326 was replaced by the similarly 389-derived 350, which used a bore and stroke for a total displacement of . Like the 326, it was offered in both 2-barrel and 4-barrel versions. In 1968, a HO option was offered in the Tempest and Firebird. The 1969 HO 350 HO was equipped with the 's large valve heads (# 48's) and the 400 HO camshaft and rated at . In 1974 it was used in the GTO and was rated at (303
In 1969, Pontiac unveiled its Trans Am model Firebird, and since racing rules required engines of less than , Pontiac unveiled the 303 for racing models only, never available to the public. Bore and stroke were . It was rated at .301
The 301 was offered from 1977 to 1981 and also installed in other GM cars during those years. The 301 had a bore and stroke of . Based in part on designs for the "short deck" engine designed for the 1970 racing season, it had a shorter deck than the big V8, and used thin-wall castings to reduce weight. 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. This resulted in a lightweight design weighing less than the Chevrolet small-block V-8. Power output ranged from to . The heads were a new design featuring siamesed intake ports. The short-deck block and different intake ports also required the design of a new intake manifold. The Pontiac 301 EC (Electronic Controls) version offered in 1981 produced and , although it's rumoured that the actual output was closer to . Although it is much different from the original 1955-vintage Pontiac V-8 powerplant, the 301 has the distinction of being the last true Pontiac V-8 engine, as Pontiac ceased production of these engines effective April 1, 1981. From 1977 to 1981 there were 4 distinct 301 versions: * 301 2-barrel (), (5th character of the VIN is a "Y" for 1977-1979). * 301 4-barrel (), (5th character of the VIN is a "W" for 1978-1980, and the 8th for 1981). * 301 4-barrel 'W72' or 'ESC' () (with the 5th character of the VIN being a "W" for 1979-1980 and the 8th for 1981). * 301 Turbo (), (with the 5th VIN character being a "T". for 1980, and the 8th being a "T" for 1981). For 1981 model year vehicles, the engine codes are the 8th digit of the VIN. The 2-barrel version was last offered in 1979. The 4-barrel version was available from 1978 to 1981 and the Turbo version was limited to the 1980 and 1981 model year, however, it was originally intended to be available for the 3rd generation Firebird before its cancellation by GM.301 Turbo
The 301 Turbo was unique since it had a beefier block than the 1977–79 versions (which carried on in the non-turbo versions in 1980 and 1981), a very mild camshaft with lift and 250 degrees gross duration, a 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 Quadrajet carburetor. This had extra-rich "DX" secondary metering rods and a remote vacuum source for the primary metering rod enrichment circuit to allow the Power Enrichment Vacuum Regulator (PEVR) to release the primary metering rods to move to the up position (enrichment) anytime during boosted conditions. This was to ensure there was enough fuel to cool the cast offset dished pistons. Boost was wastegate limited to . The 301 Turbo package mandated air conditioning, the THM350 (sometimes referred to as the CBC350 in various literature) non-lockup automatic transmission (THM350C lockup in 1981 Trans Ams), and 3.08 rear axle gearing. The 1980 301 Turbo was rated at at 4400 rpm and @ 2800 rpm. The 1981 301 Turbo gained the electronic controls with an O2 sensor, feedback ECM and E4ME265
Based on the same short-deck as the 301, the "LS5" was offered only in 1980 and 1981. It could only be ordered with a TH200 automatic transmission and a 2bbl configuration. It was implemented as further development of a cost-effective, more fuel efficient V8 derivative of the 301 V8 for the CAFE requirements. It featured a smaller bore of coupled with the same stroke of the 301 (same bore and stroke used by Chevrolet when the first small block motor was introduced in 1955). It produced After 1981, the Pontiac V8 was replaced entirely by the GM "corporate" V8's from Chevrolet and Oldsmobile. Applications: * 1980-1981Large-journal engines:1961-1976
421
The was introduced in 1961 as a dealer-installed Super Duty option. Unlike previous enlargements of Pontiac V8s, it did not replace the 389. The first of the "big journal" Pontiac V8s, it had a bore and stroke of and came with dual four-barrel carburetors. It featured main journals (which the legendary428
In 1967 the 421 was enlarged to by increasing its bore to . Both Chevy and Ford had 427 cu in performance engines, so Pontiac simply referred to its 427 as a 428 to one-up them. It retained the 421's stroke and main journal. Offered from 1967 to 1969, it produced in 1967, in 1968 and in 1969. The crankshaft in the 428 had a "N" cast on them (designating nodular steel) as opposed to the 421's Armasteel. In 1969, Pontiac also used a revised crankshaft out of a Pearlitic malleable-iron, although it still used the "N" casting letter. This new material had stronger alloys in the iron. All 428 cylinder heads received the 14 degree valve angle, closed chamber only in 67 and open chamber 68 and up. The 428 was factory installed in large cars only. However, a few dealers would offer them in the GTO or Firebird and do their own installations, such as Royal Pontiac who offered the "Bobcat" conversion. It was replaced by the 455 for the 1970 model year.455
The 428 was increased to in 1970. Again, its bore was expanded, this time to . The stroke increased to . It was rated at , but the Grand Prix with the same specifications was rated at . The horsepower ratings of this era were often dubious, with engines rated higher or lower in output for advertising, political, or insurance purposes. Though listed as slightly less powerful than some high-performance iterations of the 400 (such as the Ram-Air), the 455 had of torque, . The engine was available in all full-size Pontiacs. An HO version could be ordered in the GTO, as GM had lifted its restrictions on offering engines larger than in mid-sized cars (resulting in the Chevrolet Chevelle, Buick Gran Sport, and Oldsmobile 442). For 1971, Pontiac introduced another High Output (HO) version with standard internal parts, a reinforced block with four-bolt main bearing caps, and improved cylinder head design with intake ports and special round exhaust ports for better breathing, yet still making just gross (or in the more accurate SAE Net system). Standard in the Firebird Trans Am, it was still a rare engine. In 1973 a further refined and even stronger but less powerful version, the Super Duty (SD) engine, was planned for Firebird, Grand Am, Le Mans (GTO), and Grand Prix models. The SD-455 used round-port cylinder heads similar to those used on the 1971 and 1972 455 HO, with specific "LS-2" intake and cast-iron exhaust header manifolds. Still, it was the strongest American engine offered that year. Pontiac's initial plans were to use a camshaft with specs identical to the 041 Ram Air IV camshaft, but testing showed emissions, while technically compliant, did not have "cushion" to satisfy Pontiac's emissions engineers, to avoid production variation leading to any non-compliant engines being produced and sold. 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. As a result, peak horsepower dropped from 310 to 290, though torque increased from 390 to 395 lb. ft. After the SD-455 was certified with the new cam, it was production-ready but was then further delayed by the EPA mandating Pontiac recertify all of its engines when the EPA discovered that part-throttle emissions exceeded the limits. Thus in March 1973 Pontiac eliminated a timing solenoid that gave full vacuum advance and disabled the EGR valve in high gear after a period of time that happened to exceed the running time of the EPA testing cycle. Once corrected the SD-455 was recertified and was released for production in late April 1973. Given how late in the model year it was, Pontiac decided not to incur the costs of recertifying the SD-455 for other models other than the Firebird. Ultimately Pontiac produced only 295 1973 SD-455 Firebirds (252 Trans Am, 43 Formula). For 1974 another 1,001 (943 Trans Am, 58 Formula) were built, after which the SD-455 was discontinued. An evolution of the RA IV and H.O. designs, the SD-455 was a much improved engine. In addition to the more refined cylinder heads, block casting reinforcements in the lifter galley and main bearing oil pan rail area, it had forged connecting rods with larger bolts. Made with a provision for dry sump oiling, it truly was a racing engine, detuned for use in passenger cars. 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.HO engines
326 HO
A higher-output version was offered, called the 326 HO (High Output). It had a four-barrel carburetor, dual exhaust, and higher compression, and was good for for 1963–1964, and for 1965 - 1966 and the final year, 1967.350 HO
In 1968, there was also a 350 "HO" which had increased power with the addition of higher compression #18 heads (#17 and #46 were the most common 2-barrel heads), a four-barrel carburettor and matching intake that was also used on the 400 and 428 engines. There was also the addition of dual exhaust, and for vehicles equipped with a manual transmission, a slightly more aggressive camshaft. In 1969 the 350 HO was upgraded again with the addition of the 400 HO cam, commonly referred to by enthusiasts as the 068 cam. Also added was the #48 casting number heads with a chamber for higher compression, along with larger valves. Free-flowing exhaust manifolds from the 400 Ram Air were used late in the model year. This was underrated at .400 HO
Officially named the Quadra-Power 400 for 1967 and renamed 400 HO for 1968, the 400 HO was first offered for 1967 as the third engine in the GTO line after the automatic-only 400 2-barrel and the standard 400 4-barrel (the 400 HO would not be offered in the Firebird until the 1968 model year). For the 1967 GTO the engine was rated at and had the cast-iron headers. The camshaft was the HO cam with 288/301 duration. It was the top-of-the-line engine unless one opted for the "Ram Air" V-8 derived from it. As Pontiac's 1967 performance brochure said, "You can add the Ram Air induction hood scoop and new high output cam and valve springs to the Quadra-Power 400 for better top end breathing." But the "Ram Air" 400 also mandated steep 4.33:1 gears(or 3.90:1 in Firebird), making the Quadra-Power 400 (400 HO) the top practical street engine option for most drivers. 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). The 400 HO was offered as an option for 1967-1970 for GTO and 1968-1970 for Firebird. For 1969-1970 GTO the 400 HO included driver operable Ram Air induction and was renamed "400 Ram Air" for 1969 and just "Ram Air" for 1970. In the Firebird Ram Air induction for the 400 HO was a separate option for 1969(included with Trans Am) and included with the engine(optional in Formula; included with Trans Am) in 1970.400 W72 "T/A 6.6"
At the end of 1976, Pontiac was no longer able to continue production of the 455 (7.5 L) V8 motor due to the tightening emissions requirements. As Pontiac still wanted to offer a performance motor to compete in the performance market, they looked back to the 400 Pontiac and how it could be improved to offer greater performance while meeting CAFE standards. In 1977 the T/A 6.6, ( RPO code W72) was created to fulfil the performance engine gap in the Pontiac line-up. The W72 offered many improvements over the standard L78 400 Pontiac. One of the key upgrades were the 6x4 heads. 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. These heads can be distinguished from 6x8 heads through a small stamped "4" on the top of the front boss. The head design was incorporated from the earlier 1970's 350 Pontiac heads, and could satisfy emissions in all states except for high-altitude emissions states and California. The W72 also featured a camshaft with a higher duration, finer tuned 800cfm Rochester Quadrajet, insulated fuel line, larger 60PSI oil pump, chrome valve covers, a larger harmonic balancer, and the "T/A 6.6" Shaker decal. All of these improvements provided the W72 with a power rating of at 3600 rpm and of421 HO
First offered as an option in 1963, the 421 HO came in a 4-barrel engine of and one Tri-Power H-O version with a hotter cam and efficient iron exhaust manifolds and rated at . Pontiac offered this to the public as a streetable version of the 421 SD. The engine came with 543797 (4-barrel) and 9770716 heads for the tri-power and special exhaust manifolds and a 7H cam with 292deg. intake duration and later 1964 L with 288deg intake essentially the same as the 068 cam. #9770716 aka "716" heads featured a 170cc intake port volume, and were considered a milder "street" version of the vaunted SD421 Super Duty heads. These same heads were also used on the 1964 GTO 389 tri-power engines. By 1965 and 1966 the same combinations would be rated at for the 4bbl and the two Tri-Power versions would be rated at and the H-O version at .428 HO
This engine was first offered in 1967 as the top engine option in full-size Pontiacs. It was rated at 376 bhp in 1967 and 390 bhp in 1968 and 1969. For 1967 only Pontiac called this engine the Quadra-Power 428. It was renamed 428 HO for 1968.455 HO
;1970 The 455 HO designation made its debut in 1970; Rated at (depending on which vehicle it was installed into) & of torque, it differed from the regular full sized car 455 by large valve heads with smaller combustion chambers, and a larger camshaft. The 1970 '455 HO' was a conventional "D" port engine. It was rated at 360 hp @4300 RPM in the GTO and 370 @ 4600 RPM in the Grand Prix and other full-size Pontiacs. Ram Air induction was optional in the GTO, though power ratings were unchanged. Late in the model year the Ram Air 455 HO was made an available option for those GTOs with the optional "The Judge" package. ;1971 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. The 1971 Pontiac 455 HO was Pontiac's first engine to receive a special Rochester Quadra-jet carburetor with specific jetting. The 1971 455 HO was rated at @ 4,800 rpm and of torque @ 3,200 rpm ( gross). The 1971 455 HO was available in the Firebird (optional in Formula; standard in Trans Am), the GTO (standard with "The Judge" package), and the 2-door LeMans, LeMans T-37 (including GT-37), and LeMans Sport. Ram Air induction was optionally available with the 455 HO in the Firebird Formula(standard on Trans Am), GTO (standard with "The Judge" package), and 2-door LeMans Sport when the T41 Endura Styling Option was also ordered. ;1972 The 455 HO moniker was again carried over, this time as a near-exact repeat of the 1971 offering, the only changes were the carburetors (they used a conventional unit this year), and the head castings (casting #7F6). 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. The 1972 455 HO was rated at @ 4,000 rpm and @ 3,200 rpm. The 1972 455 HO was available in the Firebird (optional in Formula; standard in Trans Am) and 2-door LeMans (including those with the GTO option) and LeMans Sport convertible. Ram Air induction was optionally available with the 455 HO in the Firebird Formula (standard on Trans Am), and the 2-door LeMans (including GTO). ;1975 After the 1974 SD455 was dropped the 1975 Firebird's top performance engine was an 'L78' Pontiac . Pontiac still offered the regular 455 (RPO L75) in its full sized cars, and after a negative public reaction for dropping the 455 engine, it was re-introduced mid-year as an available option for the 1975 Pontiac Trans Am. However, the engine used in these Trans Ams was the same regular production 455 taken from the big body cars Pontiac was producing, and output 200 HP with a torque rating of 330 lb⋅ft at 2,000 rpm. The 455 HO package was only available to late model year Pontiac Firebird Trans Am's, and was mandatory with a 4-speed transmission. The shaker wore the decals "455 H.O." like the earlier 1971-1972 motor, but it was not the same motor, and featured standard d-port heads with a very conservative camshaft. The 1975 455 HO package received some negative press/reviews as some buyers expected to see a return of the 1971-1972 engine, and were disappointed when they received the lower output motor. Upon reflection, many did not consider that it was the only large displacement engine still on offer for any performance car on the market, and reconsidered Pontiac's position between the rising CAFE emissions restrictions. ;1976 The L75 455 engine continued as an option into the 1976 model year for the Trans Am, however, Pontiac opted to drop the "H.O." moniker from the shaker due to the disappointing public approval as the motor was not deemed to be "High Output". The 455 was fundamentally the same for the 1976 model year, albeit the shaker decal now just read "455". This was the last run for the 455 (7.5 L) motor from Pontiac, and production ceased on the 455 this year as it could no longer meet the emissions requirements any longer.301 W72 "T/A 4.9"
While not related to the 400 W72, the concept was the same. The W72 301 was a tuned L37 301 Pontiac V8 with some minor upgrades. All 1980 Trans Ams received this engine as standard with the option to delete this engine choice as a credit option for the standard L37 301. The main upgrade for the engine was the ESC, (Electronic Spark Control) which provided slightly more power at with for the 1980–1981 model years. The 1981 rendition of this engine was officially called the 301-EC C standing for Electronic Controlsin the 1981 GM factory service manual, removing the need for a W72 option separately as it was now the standard motor, similar to how all W72 engines in 1979 were coded L78. One of the key modifications over the standard 301 4-barrel was the 301 Turbo block. The 301T block was significantly more durable than the standard 301 block and received a thicker bottom end. 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. A larger 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 400 from the 1978–1979 model year were also included. Unfortunately, there were no improvements in the casting number "01" small-valve high-velocity heads, which would have yielded greater improvements in power. 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.Ram Air
The beginnings of Pontiac's iconic Ram Air dynasty began during the 1965 model year. The GTO's new hood scoop design, with the inlets centrally located and mounted above the carburetor, provided the opportunity for experimentation. Royal Pontiac developed the prototype of the package on their 1965 GTO drag car and Pontiac picked up the idea and in August 1965 Pontiac offered the new Fresh Air package to dealers consisting of the parts and instructions needed to make the hood scoop functional, including the metal tub to mount to the carburetors and rubber gasket to seal it to the underside of the hood. The Fresh Air package continued into the 1966 model year. Around January 1966 Pontiac took the next step and began offering as a factory option the XS-code engine. It included a new camshaft with duration increased from 288/302 (No. 068) to 301/313 (No. 744) and a new valve spring package with dampers to positively control valve action. Valve lift stayed at just over 0.400-inch with 1.5:1-ratio rocker arms. The tri-power equipped XS-code 389 was shipped with the Ram Air pan in the trunk, and the dealer had to fit it and cut out the underside of the hood scoop to make it functional. The XS-code 389 was still rated at 360 bhp at 5,200 rpm, same as the more common WS-coded Tri-Power 389, but performance was noticeably improved on acceleration runs. Pontiac engine production records report that 190 XS-code 389 engines were built during the 1966 model year. Whether all were installed in GTOs is unknown. None of Pontiac's Ram Air engines actually enjoyed any true ram air effect. 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.Ram Air (1967- mid year 1968)
Simply called "Ram Air" by Pontiac it was the first in a series of engines available from Pontiac as regular production line options and officially called Ram Air. Hewing to GM's standing edict limiting engine size to 400 cu in for its midsize and smaller cars, the (underrated), the 400 cubic inch Ram Air V-8 was the most powerful and advanced option available in the 1967 GTO and Firebird. Its cast "670" heads had taller valve spring heights than the standard D-port heads, and the only 14-degree valve angle closed combustion chamber making these heads unique. It featured the "744" 301/313 camshaft, which offered more duration and overlap than the "HO". Along with the HO it also had Pontiac's famous cast-iron "headers", which were much better at reducing backpressure than the regular manifolds. The 670 heads were used until May 1967 when they were upgraded to become the "97" heads, which were then replaced late in the model year by the "997" heads which incorporated the upgrades of the "97" heads.Ram Air II (1968 1/2)
The 1968 Ram Air II remained at 400 cu. in., again available only in the GTO and Firebird. It was factory rated at 366 hp at 5,400 RPM and 445 lbs.ft. of torque at 3,800 RPM in the GTO, and 340 HORSEPOWER at 5,300 RPM and 430-lb.ft. of torque at 3,600 RPM in the Firebird, with only a small throttle restrictor tab on the Firebird being different. It was the first engine that incorporated Pontiac's round-port head design in a production vehicle, however the intake port was the same as other D-port heads, leaving a head which exhaust port could nearly match the intake at high valve lifts. The Ram Air II also incorporated the first computer-designed camshaft. This camshaft sported a 308-/320-degree duration with lift. This same camshaft was also used in Pontiac's 1969–1970 RA IV production cars. 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.400 Ram Air (1969) / Ram Air (1970), aka Ram Air III
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. It would later become known colloquially as the "Ram Air III", though Pontiac never called it by that name. A 400 cubic inch ram air equipped V8, it was an option on the 1969-70 GTO and Firebird Formula. For the 1969 and 1970 model years it was the standard engine in both the Firebird Trans Am and the GTO Judge. It was the same engine as the '67-'68 400 HO 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". It used the "744" camshaft (301-313) in the earlier manual trans versions, later downgraded to the "068" version, and the 288/302 duration cam with automatic transmission. It was rated at (gross) in the GTO version. Like previous generations of Ram Airs, it used Pontiac's special cast-iron "headers". It had 2-bolt main bearing caps in 1969, but went to a block similar to the Ram Air IV's in 1969 that was drilled for 4-bolt main bearing caps (but used a cast crank and cast rods). In 1970 the casting number #9799914 Ram Air 400 4-bolt main block also used the 4-bolt main caps on Ram Air applications.Ram Air IV (1969-1970)
The Ram Air IV replaced the Ram Air II in 1969. It was called the Ram Air IV due to the planned use of four air inlets. Though production cars only got the two hood air inlets the name was retained. All 1968–69 #9792506 Ram Air 400 blocks have 4-bolt caps. The Ram Air IV used the Ram Air II's camshaft but lift in the Ram Air IV was increased to thanks to the use of 1.65 ratio rocker arms (vs 1.50). The Ram Air IV heads had 1/8" taller intake ports, larger intake port volume with more airflow, yet shared the Ram Air II round exhaust ports. In addition, a shallower spherical-wedge combustion chamber moved the tuliped valve heads .040" closer to the piston at TDC, improving mixture draw considerably during the intake stroke. The Ram Air IV also used a lightweight aluminum intake-manifold that produced a weight savings of . From 1969 though 1970, the Ram Air IV was available in both A-Body (GTO, including Judge) and F-body (Firebird, including Trans Am) form. While production of 1969–70 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. Only 157 Ram Air IV Firebirds, including 55 Trans Ams, were built for 1969. 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. A total of 1,808 Ram Air IV production cars were built over its 2-year production. Pontiac continued using its round-port cylinder-head design for 1971-'72 on the 455 HO. However, compression ratios were cut dramatically, marking the beginning of the end of the muscle car era.Ram Air V
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 short deck version for SCCA Trans-Am racing, a variant forSuper Duty
SD 421
The 421SD was available in 1961 as a dealer option or over the counter then in 62 and 63 from the factory, and was fitted with a list of internal modifications designed solely to withstand the abuse of drag racing. Cam was a #541596 McKellar No. 10 with 308/320 degrees of duration and with 1.65:1-ratio rocker arms and solid lifters, special #529238 forged-steel connecting rods, forged aluminum bore Mickey Thompson pistons, #542990 forged-steel crankshaft with a stroke and diameter main journals. Dual Carter Carburetor #3433S (front) and #3435S (rear) carburetors with manual chokes and mechanical linkage. Factory heavy-duty high-pressure oil pump and eight-quart sump, four-bolt main bearing caps with Moraine aluminum bearings, and #1110976 dual-point distributor without vacuum advance. Two different cylinder-head castings were used for the 1962 model year, both with a combustion chamber volume of to produce an 11.0:1 compression ratio. Casting No. 540306 featured valves and was carried over from the previous model year, production stopped in March 1962 and then casting No. 544127 with larger valves entered production. Neither casting was equipped with an exhaust crossover.SD-455
Available only in the 1973 and 1974 Firebird Formula and Trans Am, the SD-455 consisted of a strengthened cylinder block that included 4-bolt main bearings and additional material in various locations for improved strength. Original plans called for a forged crankshaft, although actual production SD455s received nodular-iron crankshafts with minor enhancements. Forged rods and forged-aluminum pistons were specified, as were unique high-flow cylinder-heads. A camshaft with 301/313 degrees of advertised duration, 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 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. The very modest cam, combined with a low-compression ratio of 8.4 (advertised) and 7.9:1 actual resulted in SAE NET. The initial press cars that were given to the various enthusiast magazines (e.g. HOT ROD and CAR AND DRIVER) were fitted with the Ram Air IV-spec camshaft and functional hood scoops - a fact that has been confirmed by several Pontiac sources. Some production test cars ran considerably slower and yielded times in the 14.5 second/ range in showroom tune (uncited sources)- results that are quite consistent for a car with a curb weight of and the rated SAE NET figure that some sources suggest was "under-rated." 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 @ . This was a completely stock car on loan from a private owner for the test. Furthermore, this car had an automatic, air conditioning, a 3.08 axle and weighed . This test would tend to lend credence to the CAR AND DRIVER and HOT ROD tests of 1973 Super Duty cars with 3.42 gears, no air, and less weight as being representative of production specimens capable of mid to high 13-second passes at . Pontiac listed the rating at 4000 rpm for a motor that had a 5700 rpm redline on the factory tachometer. Various Pontiac sources have emphatically stated that NO versions of the SD-455 were installed in regular production cars. 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. Nevertheless, there appears in the October 72 issue of MOTOR TREND, a road test of a 1973 SD-455 Grand Am. 1975 Factory Service Manual lists the SD-455, but the SD-455 did not meet emissions for the 1975 model year and was canceled.Experimental V8s
427 Hemi SOHC
This was a project started with the end goal of building a 427 Hemi. Pontiac asked Mopar (Chrysler, Dodge, Plymouth) for help in designing it and making it work. Surprisingly, Mopar actually agreed and sent over several of the engineers that designed both the 392 and 426 Hemi. The goal of making a Pontiac Hemi succeeded but the engine was never produced. Features: * Thin-wall, cast aluminum block * bore x stroke, 8 cylinders, each having a bore of 4.342 inch and a stroke of 3.75 inch, results in a displacement of 444.21 cubic inches (7,279.34 cc); for the Pontiac OHC 427 Hemi refers to it as a "TOHC" and lists the bore at 4.257 inch—which, with a stroke of 3.75 inch, results in a displacement of very slightly more than 426.99 cubic inches (very slightly more than 6997.124 cc). * main bearings * Forged steel rods (Ram Air V style) * 12:1 compression * Mechanical Port Fuel Injection * Large-valve heads (valve diameter): intake, exhaust * Small-valve high-RPM head (valve diameter) intake, exhaust * Splayed main caps, head bolts tie into main caps. Head bolts do not pull on the cylinder wall causing distortion. * Cam drive:Pontiac SOHC 421CID V8
Most likely prompted by its development of the Pontiac OHC six, the GM division built three different experimental SOHC 421 CID V8 engines in the early 1960s. According to the engineers who worked on the project, the SOHC 421 engines produced around 625 hp and were capable of turning 7,000 rpm. One version of the engine featured camshafts driven off the front of the engine, another design had the cams driven by gears off the back of the engine. Apparently at least one of these engines survives under the hood of an engineer's personal Pontiac.3 Valve SOHC
See also
* Pontiac Trophy 4 engine *References
{{DEFAULTSORT:Pontiac V8 Engine V8 V8 engines Gasoline engines by model