Since the mid-'60s and the introduction of the RB engine (raised block), Mopar guys have had it pretty good. The venerable 440 has always been a relatively cheap, reliable source of horsepower and torque. Enthusiasts devoted to other brands have to pay extra for things that are stock on the Chrysler big-block, such as an external oil pump and shaft rockers. The skirted block, although heavy, provides a very stable bottom-end platform, and the cavernous crankcase lends itself to the addition of various stroker cranks without much fuss. However, since stroker engines can be expensive, do you really need the extra inches to make 500 street-friendly horsepower and 525 lb-ft of torque? That's the question we put to Mike Johnson at JMS Racing Engines in Monrovia, California. Johnson says, "No problem, with modern cam profiles and cylinder heads, 500 hp and 525 lb-ft should be relatively easy, and it shouldn't cost too much, either."
Johnson suggests the use of Edelbrock Performer RPM cylinder heads. Used in conjunction with stock replacement KB Silvolite hypereutectic pistons, the closed-chamber design of the 84cc heads provides a great quench area to deter detonation and puts the compression ratio at 10.3:1 when the pistons are at zero deck height. The heads can be used right out of the box with a Performer RPM manifold.
Johnson tells us the LY connecting-rod forgings are plentiful, inexpensive, and reliably capable of handling much more than 500 hp when equipped with quality hardware. Pre-'73 440s all have forged cranks that also will handle the load, so we used these essentially stock components.
Lunati ground the cam using some lobes designed specifically for the Chrysler lifter. As most Chrysler guys know, the large 0.904-inch lifters allow for faster ramp rates and higher lift without the penalty of long duration times, and Johnson planned to take advantage of this. He wanted the torque curve to be flat, with peak horsepower coming in below 5,800 rpm, so he chose a solid flat-tappet cam with 239/243 degrees of duration at 0.050 and 0.536/0.547-inch lift. The exhaust flow of the Edelbrock head is good enough that a larger split between intake and exhaust duration isn't necessary at this power level. The cam was ground with a 110-degree lobe separation and an intake centerline of 106 degrees.
On a dyno, this combo made 527 hp and 557 lb-ft. The peak horsepower was achieved at 5,600 rpm, and the peak torque occurred at 4,100 rpm, making over 500 lb-ft from 2,900 rpm all the way to 5,500 rpm. In fact, the average torque throughout the entire pull was 529 lb-ft. Even with all that power, it still pulled 12 in-Hg at an idle, just perfect for the street.
Description PN Source PriceEdelbrock RPM Chrysler heads 60929 Summit Racing $1,359.00Edelbrock RPM manifold 7193 Summit Racing 199.88KB Silvolite pistons KB237 Summit Racing 313.99ARP rod bolts 135-6402 Summit Racing 51.88Lunati cam/lifters custom Lunati 169.95Crane 1.5 rocker arms 64790-1 Summit Racing 349.95Holley HP 950 80496-1 Summit Racing 679.95
JMS Racing Engines; Monrovia, CA; 626/357-2718; jmsracing.com