Video: 428ci Pump-gas Small-block Mopar Built For Drag Week

Hot Rod Magazine‘s Drag Week takes competitors through an absolute torture test of five dragstrips in five days, coupled with a drive to each track eclipsing over 1,000 miles, all with no support vehicles permitted. Drag Week includes an insane assortment of vehicles like Larry Larson’s Nova and Jeff Lutz’s heavy Chevy that compete in a number of different classes, from those equipped with power-adders to those doing the deed naturally-aspirated.

Johnson selected a 48 degree 9.56″ deck height Mopar Performance R3 race block for this application. He then used the shop’s RMC CNC block machining center to lighten the lifter valley before installing bronze bushings in the lifter bores with .028-inch oil feed holes.

This video from Shady Dell Speed Shop shows an engine recently completed for a customer planning to take on that torture test in the naturally aspirated small-block class. It features a number of killer parts assembled together under Shady Dell’s Ryan Johnson’s watchful eye in order to achieve the numbers needed to be competitive. 

The class features a 428ci limitation, and Shady Dell was able to coax 712 horsepower at 7,000 rpm to go along with 603 foot-pounds of torque from the Mopar engine. It was assembled from a Mopar Performance tall-deck 4.125-inch bore R3 race block with 4-bolt 340 main journals. The engine relies on a K1 Technologies 4-inch stroke crankshaft, K1 6-inch connecting rods and a set of custom flat-top, coated Diamond pistons with a 1.5/1.5/3mm ring pack to come up with the final displacement number.

“This block uses a 48-degree lifter bore angle. It helps to straighten up the pushrods, as the factory block is a 59-degree angle that puts the pushrod in a bad bind. It also uses a small-block Chevy lifter bore spacing, and for those we use an SBC .903-inch sprint car lifters typically,” Johnson explains.

The Indy 360-1 cylinder heads received competition CNC porting and hand blending to finish off the process.

The Indy 360-1 cylinder heads received competition CNC porting and hand blending.

With 11.6:1 compression on tap, a free-flowing set of cylinder heads was an absolute requirement. To that end Johnson selected a set of Indy Cylinder Heads‘ finest 360-1 245cc CNC-ported cylinder heads equipped with Ferrea Competition Plus stainless 2.125-inch intake and 1.60-inch exhaust valves. The custom-ground Shady Dell Speed Shop camshaft has large duration numbers of 272/275 at .050-inch of lift in order to evacuate the cylinders through the use of 1.65 T&D rocker arms. PSI endurance-style valve springs are used for longevity, and SDSS keeps the valvetrain weight down through the use of titanium retainers.

Building for longevity

“Since this engine is destined for a lot of hard miles, I went a bit more conservative on the camshaft dimensions. We limited the camshaft ramp speeds and camshaft as I would have liked to on a typical race engine. Most of the guys who buy these engines are looking to run 500 miles a year rather than the thousands of miles this customer is looking for,” says Johnson.

The Indy Cylinder heads 360-1 intake manifold is a deep single-plane design with long runners and gentle bends for smooth airflow entry into the cylinder head.

The Indy Cylinder Heads 360-1 intake manifold is a deep single-plane design with long runners and gentle bends for smooth airflow entry into the cylinder head.

An Indy 360-3R intake manifold sits on top, and fuel is dispensed through a Holley 950 Ultra HP carburetor, and in keeping with the class requirements must be straight-up pump fuel.

Shady Dell has specialized in the niche-market small-block Chrysler LA platform for over two decades, and Johnson got his start with the small-block Mopar engine for a simple reason.

“I grew up around these cars. In my teenage years, I couldn’t afford anything else. By the time I was in college, I was porting heads in college for guys all over the country,” he reminisces. “We started out as a cylinder head porting shop, and one of the larger guys went out of business right around the time I was getting started – we ended up buying some of his equipment. It’s a small market, but we’re doing about 40 engines a year, and I seem to be doing less porting and more engine building these days since the advent of CNC heads.”

They have quite a bit of custom equipment on the premises, and perform block work for customers all over the country with an in-house RMC CNC V30 block-machining center.

“We’ve done a lot of custom programming on that machine specifically for the Chrysler block. We have programs that lighten the blocks, and I’ve taken 56 pounds out of the tall-deck R3 block with our programming. It’s all about maintaining tighter tolerances – when I deck a block to 9.560 inches, it’s 9.560 within one ten-thousandth everywhere on the deck. It takes a lot of the guesswork out of it, since everything is done to blueprint spec,” adds Johnson. 

About the author

Jason Reiss

Jason draws upon nearly 15 years of experience in the automotive publishing industry. Collaborating with many of the industry's movers and shakers assists him in the creation of compelling technical articles and high-quality race coverage.
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