 Let’s talk about small blocks. Chrysler small-block performance really got its start with the release of the “LA” series in 1964. Although the venerable 318 “A” engine had been around since 1957, it was simply a workhorse V8 with very few performance
pretensions. With the LA engine, Chrysler had its first modern “thinwall” V8. Debuting in 273 cubic-inch form, the engine was installed in the small A-body series of cars such as the Valiant and early Barracuda. The solid-cammed, 4-bbl 273 in the ‘66 Barracuda Formula S made 235 horsepower which was certainly respectable and fun in the lightweight car. The serious small-block performance, though, arrived with the 340 in 1968.
The 340 was designed from the outset as a performance engine. From the forged-steel crankshaft and connecting rods (which were also shot-peened by the factory for stress-relief), to the big-valve (2.02” intake, 1.60” exhaust) free-flowing heads, the 340 was built to run hard and live doing it. The ‘68 edition made 275 horsepower with a single 4-bbl Carter carburetor.
 Three 2-bbl Holleys, forged bottom end, big valves, high-flow heads... Chrysler’s TA/AAR 340 6-bbl resume' reads like a speed-shop inventory list. |
Chrysler’s 340 reached its highest state of tune in 1970 with the famous 340-6 bbl engine. Designed for use in the popular and hotly contested SCCA Trans-Am racing series in the Plymouth AAR ‘Cuda and Dodge Challenger T/A, the engine’s most striking feature was the use of three 2-bbl Holley carburetors on an aluminum intake manifold. Chrysler engineers designed a special block for the AAR/TA engine which featured extra-thick main webbing to allow for 4-bolt main bearing caps. The previously mentioned forged crank, rods and pistons were carried over. Compression remained at 10.5:1, while the hydraulic camshaft was also the same (.430” intake, .445” exhaust) grind used in the standard 340. The cylinder heads had special, widened intake ports that were made possible by relocating the intake pushrods. Another unique aspect of the AAR/TA 340 was the fully adjustable valve train operating the 2.02”/1.60” valves. Chrysler severely underrated this screamer at 290 horsepower. This was, not coincidentally, the same rating applied to Chevy’s Z/28 302 and Ford’s Boss 302, both of which were also Trans-Am “specials”. In competition form and destroked to the SCCA-mandated 305 cubic inches, the AAR/TA engine produced around 440 horsepower.
While the Chrysler small blocks were excellent performers, the muscle car era was built on big blocks, and this is where the company excelled. Two basic big-block engines were produced by Chrysler during the ‘60s and early ‘70s, the “B” series and the taller-deck “RB” or “raised B”. The B engines all share a common stroke of 3.38”, while the RB engines all share a 3.75” stroke. Even the mighty 426 Hemi was based on the RB bottom end. Performance development on Chrysler’s big blocks began in 1960. Like the 409 Chevies and the 421 Pontiacs (discussed later), these early engines were aimed squarely at the drag strips and oval tracks around the country.
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The phrase “engineering excellence” sums up the Chrysler engine history nicely. Their successes on the race tracks and streets of America speak volumes about the commitment of Chrysler to performance. This commitment resulted in truly legendary engines and a following that borders on the fanatical. Of all those who profess loyalty to one particular brand, it seems none do so with as much vigor as Chrysler people.