Sharing a deep-skirted Y-block design with the big-blocks of old, this Hemi uses steel cro
Knowing that the Hemi comes with a 9.25-inch deck height, Bob subtracted the rod length and half of the stroke, leaving a 1.1-inch piston compression height that he related to Mahle, as they were contracted to manufacture the pistons for this build. Mahle coated the piston skirts with their Grafal coating and were able to reduce the piston-to-wall clearance, limiting piston rock and the wear, noise, and loss of compression associated with it.
All of the late-model Hemis came with hydraulic-roller camshafts, and Bob’s bullet was no different. Without the vast array of dyno data that would accompany something as mundane as a small-block Chevy, it took a bit of figuring to get a cam that would work the way he wanted it to. The requirements that Bob spec’d out were that the engine must make huge average torque and horsepower between 2,500 and 6,500 rpm, as the engine was to be used in the AMSOIL Engine Masters Challenge prior to its final destination in the ’Cuda. He spoke at length with Billy Godbold at COMP Cams who sent him a “small” and a “big” cam to try out. Like the older LA small-block engines, the Hemi uses a 57-degree lifter angle; however, they dropped the lifter diameter to .842 inch, like the GM camp. According to COMP, lifter angle and diameter, specifically the lifter roller wheel diameter, plays a huge role in determining the design of the cam lobes. Between those things and understanding how the Hemi heads flow compared to a typical Wedge head, the late Hemi cams are completely different than a “normal” cam. Additionally, the 2009-and-newer 5.7s employ Variable Camshaft Timing (VCT) that uses pressurized oil running to a unique camshaft sprocket, which can change the camshaft phase, advancing or retarding the cam as needed. Fortunately, Bob wasn’t saddled with that extra challenge when choosing a cam, since his was an earlier block. His final cam choice was cemented after speaking with cam guru Dema Elgin of Elgin Cams, who ground a COMP core to specs in between the “small” and “big” cams, which turned out to be the perfect choice.
Beehive valvesprings like the ones Bob used are increasingly popular for a few reasons: Th
When Bob was initially disassembling his engine and giving it the once-over, he did notice one more peculiar thing about the late Hemi: No oil galleys were feeding the lifters. Unlike most engines, the late Hemi feeds oil backward, from the top through the rockers, to the pushrods and finally to the lifters. Bob’s engine used the factory rocker arms for the engine, since at the time nothing in the aftermarket was available. “There’s nothing special about them, but there’s nobody making a set. Even at the PRI [Performance Racing Industry] Show you’re walking around and nobody’s making a set. You’re like ‘it’s been seven years guys and still nothing?’”
He had an “opportunity” for learning when freshening up the original rocker shafts. Since the heads were overheated originally, they were covered in scale, and being the fastidious engine builder that Bob is, he decided to pop out the freeze plugs in the ends of the rocker shafts to clean the inside. It turns out replacement plugs are not available, even from Chrysler. After much hemmin’ and hawin’, he just went down to the local dealer resigned to the fact that he’d have to buy new shafts to slide his nice, clean rockers on. Well, the shafts are only sold with rockers on them. (Head drops here.) On the plus side, a full set of brand-new rockers and shafts was only $140 a head. For both heads it was only $280! “Another lesson learned about the Hemi,” Bob says.
The perfect cam he now had was significantly dependant on the cylinder heads bolted on top of the block. To get the most out of the combination, Bob went straight to the horse’s mouth. He contacted Bryan Maloney of Maloney Competition Systems in Martinsville, Virginia, who was one of the original developers of the current 6.1 Hemi head and had a serious pedigree in the racing community. Maloney ended up porting the heads and intake to take full advantage of the big Ferrea 2.05/1.55 valves. On Bob’s flow bench, he says that while peak flow numbers aren’t everything, they do perform quite well, drawing in over 300 cfm by a scant .300-inch valve lift. That is one haulin’ port.
The Mahle custom pistons swinging from Callies Compstar rods look like factory pieces. Bob
What started out as a wide road-race pan from Moroso ended up under the knife. To compete
Oil is fed to the top end via two oil passages near the center of each of the two lifter h