Among the pantheon of great engines, Chrysler's 440 is a Thunder God of torque. In a sense, this attribute made the 440 a victim of its own success; the 440's Earth-moving torque made it a perfect fit for a number of large sedans, motor homes and other heavy-duty vehicles and, as such, it lacks a bit of mystique compared to the race-bred Hemi. However, its bourgeois origins couldn't keep this biggest of Chrysler big-blocks from attaining as legendary a status as any of its contemporaries from GM or Ford.
There's nothing wrong with a more-or-less stock rebuild if you're just looking for a reliable and "torquey" motor to power your classic Chrysler or motor home. However, you can take advantage of some modern technology to boost power, fuel efficiency and reliability. Modern electronic distributors are more powerful and reliable than old points-type distributors, and will far outlast their mechanical counterparts. Consider also a modern carburetor, dual-pattern camshaft and a set of used headers in place of the original exhaust manifolds. Having a three-angle valve job cut into the valve seats will boost low-rpm torque, and an electric cooling fan and water pump will boost power and fuel-efficiency across the board.
You know you're talking about a bad engine when 400 horsepower and 450 lb-ft of torque is "fairly mild." If you're looking for some fat horsepower without sacrificing your car's street manners, throwing a few basic hot rod parts at your block can accomplish the task. You'll need a set of 10-to-1 flat-top pistons, chrome-moly bolts throughout the engine, an adjustable roller-rocker valvetrain, a camshaft with about 238/intake and 246/exhaust duration at 0.050-inch lift. You'll need a high-flowing, dual-plane intake with a set of full-length, 1 7/8-inch headers and a fully modern ignition system. Consider purchasing a power package like the Performer RPM package that takes all of the guesswork out of matching the cam, heads, intake and carburetor to produce the desired power.
MOPAR'S power strategy has for decades been "go big or go home." A 440 block will readily take 500-plus cubic inches using a stroker kit, but you might want to consider scrapping the engine block and starting with a 1972 to 1973 400 block, which has far thicker main web reinforcements to handle the 500's huge torque. The 400 is a low-deck design, but will still expand to over 512 cubic inches with some machine work. Apply the basic rebuild tip described in Section 1 to a 500-plus engine and you can easily net 400-plus horsepower and 500-plus lb-ft of torque with a glass-smooth idle. A 512 subject to the same treatment described in Section 2 should net you an easy 500 horsepower and 550 lb-ft of tire-shredding torque.
Nothing beats a turbo setup for horsepower, torque and versatility. How you build your engine block depends upon how much power you want to make; ultimately, the engine block itself is what limits power potential. A 440 block reinforced with a main-bearing girdle can withstand about 800 horsepower before the crankshaft drills itself into the ground; a stronger 400 block can go to around 1,000 horsepower with reinforcements. Either way, you'll want to use a set of 8.5-to-1 forged pistons, forged steel rods and crankshaft, steel main caps and chrome-moly bolts and studs throughout. Aftermarket heads flowing at least 215 cfm on the intake sides are best, but ported stock heads will work. You can use whatever camshaft you wish, as long as it works with the heads and intake and keeps the engine below 6,000 rpm or so. You don't need to use an aftermarket fuel-injection setup; a blow-thorough carburetor will work well as long as you keep the boost under 8 to 10 psi. As always, a twin-turbo setup nets you quicker throttle response and low-rpm torque, but a single-turbo setup will be cheaper.
