To some, a "Hemi" is defined as a magical lump of metal with the amazing property of tripling the value of any car with one under the hood. But real gearheads know that a motor's hemispherical combustion chambers are what makes it a hemi. The Chrysler 440 may not have the mythical status of a factory hemi-head engine, but a set of Stage V Hemi conversion heads can go a long way toward giving it all the performance of any iron elephant.
Stage V Heads
Stage V Engineering isn't the only company ever to offer Hemi conversion heads for the 440 -- Johnson Machine makes a comparable set -- but they were the first and are still the best known. Automotive mad scientists have been adapting factory Hemi heads to Chrysler big blocks almost since the 426 Hemi debuted in the 1960s, but doing so required a lot of precision machine work and consistent results were hard to achieve with the technology of the time. SVE began offering brand-new aluminum Hemi conversion heads in 1986, and have spent the better part of 25 years refining the design. Since then, SVE has also debuted a set of Hemi conversion heads for the smaller 340 block, as well.
A set of Stage V heads retain the outward appearance of any set of factory heads, so a casual observer will have to look very close to notice that the motor is actually a Wedge. The main difference between a set of Stage V heads and factory Hemi Heads is that the Stage V heads have 10 percent larger ports and that they can't utilize a dual spark plug configuration. SVE had to relocate the exhaust rocker shaft to make the conversion work, which means a second plug won't fit. The exhaust valves measure 0.04-inch smaller than a stock Hemi's, but the Stage V head's more advanced port design still allows for higher flow. While the SVE heads can utilize any brand of aftermarket Hemi intake, they do require bespoke rocker arms and shafts.
Practically no V-8 on Earth will cost you more to buy or build than an original Hemi, so it goes without saying that the very common 440 block is inherently cheaper. The thousands of dollars you'll save on using a 440 as a starting point is money that you can spend on things that you actually want to spend it on, like a 520-cubic-inch stroker crank or a turbo setup. An aluminum-headed 440 block also comes in several hundred pounds lighter than an original Hemi. Bear in mind, though, that you'll really need to rev the 440 to get it into the Hemi heads' operating range, so plan accordingly.
A 440 block may lack the cross-bolted mains and extra reinforcement that make a Hemi capable of withstanding thousands of horsepower, but the Wedge is no slouch where power potential is concerned. Even a garden-variety two-bolt main truck block can withstand over 800 horsepower, and an aftermarket four-bolt block can take as much abuse as any Chrysler motor. While 1976-and-later 440s have the thickest main webs and strongest blocks of all the engines in this displacement range, you might consider starting with a 1972 to 1973 400 block (casting number 3614230) instead. These blocks have truly massive main saddles, and are among the strongest Chrysler blocks ever produced, short of the Race Hemi. The 1973-only 400 (casting number 3698630) is good second choice if you can't find an older block, but its main saddles are nowhere near as thick.
- "Ultimate American V-8 Engine Data Book, 1949-74, Second Edition"; Peter Sessler; 1999
- Stage V Engineering: Aluminum Hemi Conversion Heads
- "Hemify Your Wedge"; Steve Magnante; Popular Hot Rodding; February 2009
- "Building a Hemi for Less"; Steve Magnante; Car Craft Magazine; February 2009
- "Half-Price Hemi"; Steve Magnante; Hot Rod Magazine; June 2009
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