pontiac 389 pushrod length

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First offered as an option in 1963, the 421 HO came in a 4-barrel engine of 320hp (239kW) and one Tri-Power H-O version with a hotter cam and efficient iron exhaust manifolds and rated at 370hp (276kW). 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. This same camshaft was also used in Pontiac's 19691970 RA IV production cars. aluminum V8 it had offered in the Tempest and replaced it with a small-bore version of the standard 389cuin (6.4L) Pontiac V8. 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 engine came with 543797 (4-barrel) and 9770716 heads for the tri-power and special exhaust manifolds and a 7H cam with 292deg. In this case, measuring the length of a pushrod needs to be precise. The V8 engine was introduced for the 1955 model year as the "Strato Streak". 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. 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.[14]. Also, I don't believe your heads have screw-in studs odds are great that you popped the rocker stud loose from too much lift, which allowed the pushrod to jump out. Machine shop provided i believe when they went to positive valve seals and removed the hats. in., again available only in the GTO and Firebird. So a 7.800 base length pushrod turned five revolutions from its starting point would equal 0.250-inch. This will require more precise measurements. 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. 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. Below are the available bulk discount rates for each individual item when you purchase a certain amount, Heat Treated, .065" Wall, Chrome Moly Pushrods, Elgin 800 Series. 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. 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 4 July 2022, at 06:04. The 301.6cuin (4.9L) 301 was offered from 1977 to 1981 and also installed in other GM cars during those years. It was called the Ram Air IV due to the planned use of four air inlets. The 1968 Ram Air II remained at 400 cu. A quick way to get close to the proper pushrod length is to first paint the top of the valve tip. The camshaft was the HO cam with 288/301 duration. 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. Surprisingly, Mopar actually agreed and sent over several of the engineers that designed both the 392 and 426 Hemi. The Pontiac 301 EC (Electronic Controls) version offered in 1981 produced 155hp (116kW) and 245lbft (332Nm), although it's rumoured that the actual output was closer to 170hp (127kW). This was to ensure there was enough fuel to cool the cast offset dished pistons. The stroke increased to 4.21-inch (106.9mm). Suitable for up to 500 Lbs open pressure. The 1980 301 Turbo was rated at 210hp (157kW) at 4400rpm and 345lbft (468Nm) @ 2800rpm. Splayed main caps, head bolts tie into main caps. Instead, they were substituted with the L80 Oldsmobile 403, or the L37 Pontiac 301 if they still requested a 4-speed transmission. The cylinder heads on the 400 CID version had an intake port volume of 290cc (17.70cuin), nearly twice the size of a typical standard D-port Pontiac head - and flowed in the area of 315cuft/min (8.9m3/min) @ 0.8in (20mm) valve lift; in the realm of the NASCAR-dominating Chrysler 426 Hemi. 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. Setting proper pushrod length benefits all engines, but is especially critical in high rpm applications. This was based on results of over 1 million test miles, which was unheard of at the time. No parts for vehicles in selected markets. Enter your email address below and click the 'Notify' buton to receive notification when this item is available again: Enter a note to be sent with your notification (optional): Not Valid With Any Other Sales OfferThere is no minimum purchase amount required for free shipping on this item. 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. 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. For 1959 the V8's stroke was increased to 3+34in (95.3mm), raising displacement to 389cuin (6.4L). The short-deck block and different intake ports also required the design of a new intake manifold. Pontiac's SCCA Trans-Am program was promising, with race-ready engines producing 475hp (354kW) to 525hp (391kW), however the series General Competition Rules required the manufacturer to produce no less than 250 vehicles with the 303. The beginnings of Pontiac's iconic Ram Air dynasty began during the 1965 model year. One way to make life easier on the valvetrain is to idealize its operating geometry. It retained the 421's 4in (101.6mm) stroke and 3+14in (82.6mm) main journal. 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. In 1967 the 421 was enlarged to 426.61cuin (7.0L) by increasing its bore to 4.12in (104.6mm). Pontiac did not release official power ratings for this engine, saying only that it had more than 300hp (224kW). These .065" Wall Chrome moly pushrods are strong yet light, they're an excellent choice for most any high performance application. From 1955 through 1959, the Pontiac V8 was also used in some GMC pick-up trucks. The 400 remained in production through the 1978 model year, with 1979 cars receiving engines produced the previous year. This specific engine has stock valve train with bottle neck studs but poly locks for the preload adjustment. Both Chevy and Ford had 427 cu in performance engines, so Pontiac simply referred to its 427 as a 428 to one-up them. in. Not valid with other discount codes. [citation needed]. 1967 was the last year for closed-chambered heads. He replaced the regular valve seals with positive valve seals and removed the caps on the springs. 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". What are you referring to caps on springs? The 400 HO was offered as an option for 1967-1970 for GTO and 1968-1970 for Firebird. By 1979, Pontiac was no longer allowed to produce the 400 engine as emissions further tightened. 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. Please Answer The Following To Purchase This Part: This Is A Configurable Part. 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). The 428 was increased to 456.12cuin (7,474cc) in 1970. Two-barrel carburetor, 8.5:1 compression, 227hp (169kW) @ 4600rpm, 333lbft (451Nm) @ 2300rpm, Four-barrel carburetor, 10:1 compression, 244hp (182kW) @ 4800rpm, 350lbft (475Nm) @ 2600rpm, Two-barrel carburetor, 10.0:1 compression, 244hp (182kW) @ 4800rpm, 350lbft (475Nm) @ 2600rpm, Four-barrel carburetor, 10.25:1 compression, 270hp (201kW) @ 4800rpm, 359lbft (487Nm) @ 2900rpm. ). 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). 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. Standard in the Firebird Trans Am, it was still a rare engine. The 421 SD became factory installed in 1962 and in 1963 a street version became available from the factory with a dual four-barrel or three two-barrel Tri-Power carburetion. 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. [2] This was the engine installed in Pontiac's "executive" line of large cars[3] and its largest station wagon. 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. Casting No. 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 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. 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. 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 160lb (73kg) less weight as being representative of production specimens capable of mid to high 13-second passes at 104mph (167km/h). 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. I use the copper coat on both sides of every head gasket job I do. It was offered in the following forms: For 1957 the V8's stroke was increased to 3.5625in (90.49mm), for a displacement of 347cuin (5.7L). If you are assembling a new performance engine equipped with non-standard parts like 0.100-inch longer intake valves or lash caps, these components directly affect the pushrod length. Veteran enthusiasts may scoff at this because, back in the day, you just dropped in a set of stock pushrods, set the lash on that solid cam and went out and made noise. During 19511952, Pontiac had 23 287cuin (4.7L) V8-equipped 1953 model production prototypes running tests on the GM proving grounds. All 428 cylinder heads received the 14 degree valve angle, closed chamber only in 67 and open chamber 68 and up. 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. Discussion in 'The Hokey Ass Message Board' started by Willshire, Jul 11, 2011. Pontiac went to open-chambered heads in some 1967 models and all 68 and up to improve power, engine breathing and reduce emissions. In 1977 the 400-cubic-inch (6.6L) T/A 6.6, (RPO code W72) was created to fulfil the performance engine gap in the Pontiac line-up. None of Pontiac's Ram Air engines actually enjoyed any true ram air effect. 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, although some literature has indicated that the 301 Turbo may have found its way into the Chevrolet Camaro Z28. Manufactured by Elgin Industries in the USA. 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. and so the 326 bore size was reduced to 3.72in (94.5mm), giving a true 326.06cuin (5.3L). 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. Again, its bore was expanded, this time 0.03in (0.76mm) to 4.1525in (105.47mm). For those engine builders who live to be ultra-precise, custom pushrods lengths can also be ordered. But attention to these details is why custom engine building is as much an art form as it is a science. This was the beginning of factory supplied performance items such as 4 bolt main bearings and windage trays to reduce friction from crankcase oil. In 1969, Pontiac also used a revised crankshaft out of a Pearlitic malleable-iron, although it still used the "N" casting letter. The valve angle was reduced from 17 degrees to 14 degrees for better breathing. This was a project started with the end goal of building a 427 Hemi. JavaScript is disabled. [7] Though listed as slightly less powerful than some high-performance iterations of the 400 (such as the 366hp (273kW) Ram-Air), the 455 had 500lbft (678Nm) of torque, 55 more lbft (75Nm). 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). you say the pushrod length changed. - eBay Money Back Guarantee - opens in a new window or tab, - for PayPal Credit, opens in a new window or tab, Learn more about earning points with eBay Mastercard, - eBay Return policy - opens in a new tab or window, - eBay Money Back Guarantee - opens in a new tab or window. There is no positive stop below the rocker like on roller rockers just the end of the thread cut to stop the nut. Dual Carter Carburetor 500cuft/min (14m3/min) #3433S (front) and #3435S (rear) carburetors with manual chokes and mechanical linkage. A forum community dedicated to Pontiac GTO owners and enthusiasts. Now lightly rub the rocker across the valve tip to establish a witness mark on the valve tip. This was underrated at 330hp (246kW). Like previous generations of Ram Airs, it used Pontiac's special cast-iron "headers". All 1977-1978 Trans Ams ordered with the 4-speed Borg Warner Super T-10 manual transmission received the W72 T/A 6.6 engine. Get superior 210 radius end pushrods for one low price! Pricing and promotions may change at any time without prior notice. But the performance world has evolved- power numbers are escalating, engine speed continues to climb, and spring rates are growing- all of which adds to valvetrain stress. i guess if there is no oil in the lifter the cup has bottomed out so the only thing to move is the valve right? 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). PY Online Forums - Bringing the Pontiac Hobby Together. i am in the middle of installng new scorpion rollers on my 389 and it appears my p/r's will need to be .220" longer. Is this common when going from standard stamped steel to billet rollers. Copyright 1995-2022 eBay Inc. All Rights Reserved. With an identical bore and stroke of 4+116in (103.2mm) and 3+34in (95.3mm) it was precisely half the displacement of the 389 and shared numerous parts with the V8,[1] yet weighed considerably more than half as the engine lower half and block casting were not simply divided down the middle. 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 valve size increased as well, to 2.11in (53.6mm) intake and 1.77in (45.0mm) exhaust valves on high-performance heads. Other variables that affect pushrod length would be changing from a flat tappet to mechanical or hydraulic roller lifters. When fitted with other high-airflow components, it produced a good balance of low-end torque and higher-RPM power. 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). The goal of making a Pontiac Hemi succeeded but the engine was never produced. The "670" head was a 1967-only casting, and the only PMD head to have a closed chamber with the new 14 degree valve angle. Logically, half turns would equal 0.025-inch. Shown below are parts other customers have bought with. 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. Also, the new cam was about .010 longer, end to end, than the old cam {nothing to do with pushrod length--just general info}. Bore and stroke were 4.121in 2.84in (104.7mm 72.1mm) 303.63cuin (4,976cc). Pontiac differed from other GM Divisions and most other manufacturers in producing only a single small block V8, rather than adding a larger big block to its line-up. For example, the 10.800-inch version pushrod tool will extend out to 11.800 inches. While not related to the 400 W72, the concept was the same. Does the drill need to spin very fast it has been my luck that any flathead screw the thing jumps around i don't want to jump it off the oil pump rod. Along with being cheaper to build, this allowed more consistent valve action with less weight than a conventional shaft. 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. 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). Three two-barrel carburetors, 10.75:1 compression, 290hp (216kW) @ 5000rpm, 375lbft (508Nm) @ 2800rpm. 544127 with larger 2.02/1.76-inch (51/45mm) valves entered production. For the 1969 and 1970 model years it was the standard engine in both the Firebird Trans Am and the GTO Judge. 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. 301 2-barrel (135hp, 101kW), (5th character of the, 301 4-barrel (150hp, 112kW), (5th character of the. Unusual for a major automaker, Pontiac did not have the customary "small-block" and "big-block" engine families common to other GM divisions, Ford, and Chrysler. The engines feature a cast-iron block and head and two valves per cylinder. These fine pushrods feature 210 degree radius ends which allows for higher lifts without tip binding, this feature is only available on high end pushrods. 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. Different manufacturers use various pushrod seat height lifters that affect pushrod length. 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. If we paint the top of the valve stem tip with a Sharpie or machinist's dye, rocker travel will leave a witness mark that will indicate the width of valve tip travel. The 301T block was significantly more durable than the standard 301 block and received a thicker bottom end. The 1964-1974 Pontiac Tempest, Lemans & GTO, 1964-1974 Tempest/LeMans/GTO Tech/Electric Wiring, The Fora platform includes forum software by XenForo, 1964-1974 Tempest, Lemans & GTO General Discussion, Service, Maintenance and Technical Discussion, 1964-1974 Tempest/LeMans/GTO Restoration Projects, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. Each pushrod will offer one inch of travel. For 1974 another 1,001 (943 Trans Am, 58 Formula) were built, after which the SD-455 was discontinued. This engine was first offered in 1967 as the top engine option in full-size Pontiacs. Offer is not valid on previous purchases and cannot be combined with any other sale or promotion offers unless otherwise stated. The 1971 Pontiac 455 HO was Pontiac's first engine to receive a special 800cuft/min (23m3/min) Rochester Quadra-jet carburetor with specific jetting. The short deck engine weighed about 40lb (18kg) less than the other variants and had an 8000 rpm redline. 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. Sorry but this item is currently unavailable. This will generally call for custom length pushrods that may need to be physically measured as opposed to just counting the number of turns on a pushrod length checker. The 389 was the standard engine for the Pontiac GTO through 1966. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass. Pricing and promotions may change at any time without prior notice. For the 1978 model year, Pontiac re-incorporated the earlier thicker cast cast engine block denoted by the cast number 418988 and a "XX" cast into the side of the block. The main reason for this is because there is limited available adjustment range in the small threaded seat in the rocker itself. It was rated at 475hp (354kW). Set up a rocker and pushrod assembly and rotate the engine through at least two full valve lift cycles. Only other thing you need to insure is that you order the hardened pushrods. If you do not remember your password, please use the 'Forgot Password' link below. i am looking into pricing another one. 744) and a new valve spring package with dampers to positively control valve action. For a better experience, please enable JavaScript in your browser before proceeding. The 1981 rendition of this engine was officially called the 301-EC [EC standing for Electronic Controls] in 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.[16]. #9770716 aka "716" heads featured a 170cc intake port volume, and were considered a milder "street" version of the vaunted SD421 Super Duty heads. Price will be updated as you change quantities on the product page. 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. Using Trend's adjustable pushrod is very easy. Offer is only available at YEARONE.com, phone orders are not eligible. As a result, it was remarkably free of teething problems. 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. Despite their work, the division's conservative management saw no immediate need to replace the Pontiac Straight-8 until later in the 1950s. The machinist's ball should measure 0.3125-inch in diameter. These pushrods are a two-piece design with internal threads with one full revolution of the pushrod tip equal to a 0.050-inch change in length. The 1971 455 HO was rated at 335hp (250kW) @ 4,800rpm and 480lbft (651Nm) of torque @ 3,200rpm (gross). A total of 1,808 Ram Air IV production cars were built over its 2-year production. 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. By 1965 and 1966 the same combinations would be rated at 338hp (252kW) for the 4bbl and the two Tri-Power versions would be rated at 356hp (265kW) and the H-O version at 376hp (280kW). A mechanical system built by Rochester, it was similar in principle, but not identical, to the contemporary Chevrolet "fuelie". 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. Pontiac planned to produce the 1953 models with the V8, but Buick and Oldsmobile appealed to GM management and earned a 2-year delay. Assuming we are dealing a 5/16-inch cup on one end, the technique is called the "overall length measurement". Come join the discussion about performance, modifications, troubleshooting, maintenance, history, and more! Furthermore, this car had an automatic, air conditioning, a 3.08 axle and weighed 4,010 pounds (1,819kg). Pushrods that are either too long or too short only increase this distance. If you look at the accompanying diagram of how the rocker tip moves across the face of the valve tip, this description will become clear. Neither casting was equipped with an exhaust crossover. 1964-1967 Pontiac 326 V8 and 1964-1966 389 V8 High Strength Chrome-Moly Pushrod. As stated above i should have some thread left on the rocker arm studs when tightening them down no? In 1970 the casting number #9799914 Ram Air 400 4-bolt main block also used the 4-bolt main caps on Ram Air applications. The Armasteel cast crankshaft was the standard hardened cast-iron crankshaft used throughout the entire Pontiac V-8 line until 1967. Nevertheless, there appears in the October 72 issue of MOTOR TREND, a road test of a 1973 SD-455 Grand Am. Measuring a pushrod that combines both a ball tip and a cup requires the use of a machinist's ball. This will generate a close approximation of the ideal pushrod length for street engines. [4] It was replaced by the 455 for the 1970 model year. It produced 120hp (89kW) After 1981, the Pontiac V8 was replaced entirely by the GM "corporate" V8's from Chevrolet and Oldsmobile. "Armasteel" referred to its "locking ball" cast-iron, as opposed to the "flaking" type found in other engines. Engine block and cylinder heads were cast at Saginaw Metal Casting Operations then assembled at Tonawanda Engine before delivery to Pontiac Assembly for installation. 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). The pushrod hole in 389 heads are also used as guides, so the pushrods have to be hardened to avoid excess wear. Of course, canted valve heads will require different length pushrods. It was rated at 366bhp (273kW) (gross) in the GTO version. Late in the model year the Ram Air 455 HO was made an available option for those GTOs with the optional "The Judge" package. It featured the "744" 301/313 camshaft, which offered more duration and overlap than the "HO". Beginning in 1961 the Pontiac V-8 (389 and 421) was dubbed the Trophy V-8, due to its many victories in racing. This is a universal trait of all rocker arms. Once corrected the SD-455 was recertified and was released for production in late April 1973. 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. Apparently at least one of these engines survives under the hood of an engineers personal Pontiac. This offer is not transferable and will not be extended. Forged rods and forged-aluminum pistons were specified, as were unique high-flow cylinder-heads. Pontiac offered this to the public as a streetable version of the 421 SD. Ecommerce Solution by BigCommerce, Bulk Discounts for PUSHRODS, PONTIAC 326, 389, 421, 8.693" X 5/16 HEAT TREATED CHROME MOLY. Thanks for responses. Made with a provision for dry sump oiling, it truly was a racing engine, detuned for use in passenger cars. The heads were a new design featuring siamesed intake ports. 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. Other variables include cam lobe base circle size differences. WARNING: This product can expose you to chemicals including but not limited to lead, sulfur, nickel, chromium, vanadium, titanium, polyvinyl chloride and/or 4, 4'-methylenebis (2-chloroaniline) which are known to the state of California to cause cancer or birth defects or other reproductive harm.

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