Not only has the new-tech 5.7L Hemi revitalized Chrysler's new cars and trucks, it also is demonstrating great potential as a reanimator for tired old musclecars. Chrysler's performance parts division, Mopar Performance (MP), is well aware of this and has released 5.7L carbureted (PN P4510594) and EFI (PN P4510593) crate engines, as well as detailed instructions and additional components needed to install the crate engines into earlier classic musclecars. In fact, MP sponsored one of the very first new-Hemi-into-old-car swaps, having JT Automotive and Glendora Dodge transplant a crate EFI 5.7L engine and A-518 four-speed automatic overdrive transmission into a '70 Duster previously equipped with a 318 small-block and A-904 trans. The basic swap info presented here applies toany '67-'76 Dodge or Plymouth A-body chassis.
Designed for plug-and-play retrofit installations, Mopar Performance's crate Hemi fits this '70 Duster's engine compartment like a glove. These motors come complete with induction, computer, wiring harness, instructions, and accessory mounting brackets. Note how all the wires have idiotproof circuit ID tags.
Unlike a production Hemi, MP's crate motors are specifically designed for simple, easy plug-and-play installation. Besides the complete engine, you also get a standalone computer, wiring harness, accessory drives, and detailed instructions. The EFI version has a centrally located, Holley-flanged throttle-body that simplifies installation in older vehicles compared to production-based intakes and their front-mount throttle-bodies. However, if you already have a production take-out, MP has conversion kits (PN P5153339, EFI; PN P5153340, carbureted) that adapt them for retrofit duty.
New Hemi engine mounts are totally different from previous Chrysler engines. TTI has developed mounts specifically engineered for this swap (PN MM57A). The brackets work with standard Chrysler A-engine classic musclecar insulators (Schumacher sells repro insulators). TTI's mounts are designed for use with its headers (PN TTI5.7HC-C4, ceramic-coated; PN TTI5.7HC-C5, polished ceramic-coated); however, this proof-of-concept swap still used Chrysler production exhaust manifolds. TTI headers for new 6.1 production Hemis and forthcoming 6.4L Hemi crate motors-which have different exhaust ports from the 5.7s-are also under development.
The new Hemi's rear block-face bolt-pattern is similar to a Chrysler small-block A-engine. Any 727- or 904-type trans bolts up, minus the top bolt on the new transmission. However, the new Hemi's rear crank offset is 0.060 inch greater than the small-block. You can use neutral-balanced small-block 10.5-inch torque converters by removing the production-style Hemi flexplate ring gear (retain the ring gear on the converter). Stock 426 Hemi eight-bolt flexplates also fit if you elongate one torque converter mounting hole. Add any spacers as needed to make up for the different crank offset. MP will soon release a special flexplate with no ring gear that specifically accommodates standard small-block converters. It also is developing new parts to aid in manual transmission installation (so far, all production Hemis have used automatics).
Adapting the big A-518 overdrive trans to the tight A-body is the hardest part of this swap. The A-518 is the same length as the A-727, but considerable floorpan mods are required to clear its much fatter case, to the point of actually cutting into the unibody structure. Chrysler sells a remanufactured version of the A-518 (PN R2118323AC) that still uses an old-school mechanical speedo cable and does not require a computer to lock up the converter or shift into Overdrive. Another option is Keisler's conversion kit, which swaps in a slimmer GM 4L65E automatic trans that clears the floorpan.
