Chrysler 340 Six Pack!
This engine design was guided by none other than Tom Hoover, later known as ‘the father of the Hemi’. For 1970, as delivered in AAR Cuda and Dodge Challenger T/A for use in the SCCA Trans-Am Racing Series, the factory stock Six Pack 340 engine was a well-optioned animal straight out of the box. It meant business, leaving plenty of scope for modifications allowed within the racing regulations that would help it thrive in a Trans Am racing environment. There was no stone unturned, starting with a high nickel stress-relieved engine block, utilising thicker webbing in the pan rails and other areas to allow the option of installing four bolt main caps on 2,3 and 4. High-performance ‘J’ casting cylinder heads were utilised along with large diameter valves, working in tandem with a unique rocker arm/shaft/pushrod assembly. Within this cylinder head design, the pushrod holes were offset to allow more material for oversized porting on the intake runners. Forged crankshaft, heavy-duty conrods and high-performance pistons. A windage tray was also featured. A healthy 10.5 to 1 compression ratio complemented an aggressive 276/284 duration camshaft driven by a dual-row timing chain and the fire in the combustion chamber was ignited by dual points ignition with the spent gasses exiting through a free-flowing exhaust system.
One highlight of this engine combination was the Six Pack (or 6 barrel) carb set-up, running a trio of two-barrel Holleys sitting on top of a factory-fitted Edelbrock intake manifold. A 375 cfm centre carb acted as a primary, then at a given throttle percentage, the two 500 cfm outer carbs would open up and join the party to provide a whopping total of 1375 cfm in total air flow, along with an induction howl you’d never forget.
The factory officially rated the engine at 290hp and 345ft/lbs of torque. The consensus is that it produced at least 330hp, particularly when you consider its claimed 14.4 second quarter-mile capability and 5.8 sec 0-to-60 mph times in a 3500 pound car. In race spec, the engine was de-stroked to just under the Trans-Am regulations 305cu limit and during the development phase across its racing lifespan, was rumoured to have produced between 460 and 500hp.