Mighty Mopar Muscle - The Engines

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The high-performance four-barrel 340 V-8 was an inexpensive engine which offered impressive power in smaller Dodges and Plvmouths. In 1968, Chrysler introduced the 340-ci V-8. Unlike the 318, the 340 was designed as a performance engine. Its bore and stroke was 4.04x3.31 inches. (Note: The 273, 318 and 340 all had the same 3.31-inch stroke.) The heart of the 340 was its big-port, high-flow cylinder heads which measured 2.20 square inches. A well-designed 180-degree, two-level intake manifold aided breathing. In 1968, the four-barrel 340 with a 10.5:1 compression ratio developed 275 hp at 5000 rpm. Torque was 340 pounds-feet at 3200 rpm. Cam timing was 268 degrees intake, 276 degrees exhaust, with forty-four degrees of overlap for cars equipped with automatic transmissions. Cam timing for manual transmission cars was 276/284/52. Intake valve diameter was 2.02 inches, exhaust valve diameter was 1.60 inches. The crankshaft was forged and shot-peened. A special Carter ThermoQuad carburetor had 13/s-inCh primaries and huge 2'/4-inch secondaries.

In 1970, the 340 reached its highest state of development as the sixbarrel 340 T/A engine. This screamer was used exclusively in the production Plymouth AAR 'Cuda and Dodge Challenger T/A. The engine block was specially cast with thicker webs and pan rails to accommodate four-bolt main caps. Crankshaft and con necting rods were forged, as i n the high-performance four-barrel 340 Pushrods were relocated. The camshaft was radical, with 0.430-inch lift for intalte, and 0.445-inch lift for exhaust. The heart of the engine, of course, was the induction system Three two-barrelHolley carbs sat atop an Edelbrock aluminum intake manifold. The production six-barrel 340 was conservatively rated at 290 hp at 5000 rpm, with345 pounds-feet of torque at 3400 rpm. Racing versions, with a sing le fourbarrel, destroked to 305 ci, produced an honest 450 hp. The production six-barrel 340 was built for only one year.

In 1972, the 340 lost its 10.5:1 compression ratio in favor of an 8.5:1compression ratio for emissions reasons. That year, the 340 also picked upthe 360 V-8 cylinder heads with smaller intake valves. The 240-hp ratingat 4800 rpm reflected the drop in compression and adoption of SAE (Societyof Automotive Engineers) net horsepower ratings. Nevertheless, it was still a good, high-performance engine. Although production of the 340 stopped at the end of the 1973 model year, it continues to be a supremely popular street, strip and racetrack powerplant. Many aftermarket manufacturers, including Chrysler itself, still supply high-performance parts for the 340.

In 1971 , Chrysler introduced the 360-ci two-barrel V-8. It differed fromthe 340 in both bore and stroke. Bore was 4.00 inches and stroke was 3.58 inches. The 360 also differed by having the main web area beefed up to accept a larger main bearing diameter for the cast iron crank. Despite its two-barrel carburetor and a compression ratio of only 8.70:1, it was a reasonably good performer, developing 255 hp at 4000 rpm with 360 poundsfeet of torque at 2400 rpm. In 1972, net horsepower was only 175. The following year, the engine lost five more horsepower, and those bound for California lost yet another seven ponies, due to stricter emission standards.

Help finally arrived in 1974. Besides the two-barrel engine, there werenow two 360 V-8's with four-barrel carburetors. One developed 200 hp at 4000 rpm with 290 pounds-feet of torque at 3200 rpm. The other engine developed 245 hp at 4800 rpm with 320 pounds-feet of torque at 3600 rpm. Both four-barrel engines ran with an 8.4:1 compression ratio. Performancedeteriorated quickly after that, but the 360 remained in production until the end of the 1980 model run.

To the rabid street enthusiast, the phrase "there's no substitute for cubic inches" rang true. Big-blocks were really where it was at during the sixties and early seventies. These big-block Chrysler engines were identified as having either a 8-block or an RE-block. B-blocks were classified as low-block for their stroke of 3.38 inches. The RE-blocks (for raised-Bblock) had a common stroke of 3.75 inches Displacement varied according to bore.

The 383 V-8 was synonymous with Mopar performance. While there were slightly smaller performance big-blocks offered by Chrysler, most notably the 361-ci V-8, the 383 was the prime mover in millions of Dodges and Plymouths. The 383 was first introduced as a raised-blocle wedge design i n 1959, It had a bore of 4.03 inches. With dual four-barrel carburetion, it produced 345 hp at 5000 rpm and 420 pounds-feet of torque at 3600 rpm.

The following year, 1960, Chrysler introduced the 383 with wild, cast aluminum ram induction. Again, it came with two four-barrel carburetors, but they were suspended over the sides of the engine and fed into a plenum beneath each carburetor with two siamesed runners crossing over the valve covers to the cylinder head on the opposite side of the engine. There were long and short ram manifolds manufactured, but only the long units were offered on passenger cars. The short ram manifold was rare and available only through Mopar parts departments.

Actually, the long and short ram manifolds were identical dimensionally, but they differed internatly. In the long ram manifold, the wall between the pair of passages reached all the way from the plenum chamber beneath the carburetor to the cylinder head surface. On the short manifold, this wall extended only 10% inches from the cylinder head surface. The long version tuned at a lower rpm than the short unit. In other words, the long ram was designed for the street and the short ram for the strip. The short ram manifold also helped Dodge and Plymouth in stock car racing. Plymouth won eight races and Dodge one race on the Grand National circuit in 1960.

The high-performance four-barrel 383 was standard equipment in many Dodge and Plymouth muscle cars. A 383 with long ram manifolds produced 330 hp at 4800 rpm and 460 pounds-feet of torque at 2800 rpm. With short ram manifolds. it produced 340 hp at 5000 rpm and 440 pounds-feet of torque at 2800 rpm. This hot induction system on the 383 was also offered in 1961, but was dropped at the end of that model year.

In 1960, the factory altered the 383's bore and stroke to 4.25x3.38 inches, making it a low-block. According to Chrysler, the hottest 383 that year came with the famous 300J cylinder heads and a dual four-barrel inline carburetor setup that produced 343 hp at 5000 rpm. This rare engine was one of the most powerful 383's ever built. A more practical two-barrel 383 with a 10.0:1 compression ratio had 305 hp at 4600 rpm and 410 pounds-feet of torque at 2400 rpm.

There were three high-performance 383's to choose from in 1963. First was a single four-barrel unit with 10.0:1 compression that developed 330 hp at 4600 rpm. Torque was 425 pounds-feet at 2800 rpm. The next most powerful 383 had a slightly higher compression ratio of 10.10:1. With a four-barrel carburetor, it developed 360 hp at 4800 rpm and 470 pounds-feet of torque at 3200 rpm. The top-of-the-line 383 was the dual four-barrel version with compression lowered to 9.60:1. Nevertheless, it produced 390 hp at 4800 rpm and 485 pounds-feet of torque at 3600 rpm. The 305-h p two-barrel 383 was also available for more mundane chores. This year was the apex of 383-engine development, as research and development shifted to the larger-displacement engines.

The lonshorn cross-ram 383 was one of the most exotic and powerful production V-8's of the early sixties. The 383, however, continued to be a perennial favorite as a performance powerplant for the next eight years. Power output for the 383 was diminished in 1964 so as not to embarrass the horsepower ratings of the larger engines. That year the four-barrel 383 with 10.0:1 compression was rated at 330 hp at 4600 rpm and 425 pounds-feet of torque at 2800 rpm. This engine was the only four-barrel 383 that year. The dual four-barrel 383 was no longer available, but the two-barrel version continued. The horsepower and torque ratings were the same for 1965. In 1966, performance dropped a bit: The four-barrel V-8 was rated at 325 hp at 4800 rpm with 425 pounds-feet of torque at 2800 rpm with a 10.0:1 compression ratio. This remained unchanged for 1967, but Chrysler had not become complacent.

In 1968, the 383 got a shot in the arm. While the two-barrel V-8 was downg raded powerwise, the four-barrel V-8 held its own or was upgraded in performance. The Super Commando 383 developed 330 hp at 5000 rpm and 425 pounds-feet of torque at 3200 rpm. Compression ratio was 10.0:1. The air cleaner was unsilenced and the engine used a dual exhaust. The most powerful 383 that year was a special engine developed exclusively for the low-cost Plymouth Road Runner and Dodge's equivalent, the Coronet Super Bee. Chrysler bumped the output of this 383 by bolting on the highperf ormance pa rts designed for the 440 V-8 used in the Plymouth GTX and Dodge Coronet R/T, introduced in 1967.

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