What: '66 Chevrolet Chevelle
Owner: Tom Monehan
Home Town: Villa Ridge, Missouri, a thriving megalopolis of 2,400 residents west of St. Louis
Short-Block: Here is the heart of the matter. The whole engine process started with a World Products iron Merlin block machined to a 4.530-inch bore and stroked with an Eagle 4340 steel crankshaft moving the pistons a total of 4.25 inches. This makes for a 548ci package using 9.5:1-compression SRP forged-alloy pistons and Total Seal rings. A set of Eagle steel H-beam 6.385-inch rods make the connection between the pistons and the crank. Tom also uses a Milodon oil pan and stock-type pump to keep everything well lubed.
Cam: The cam that turned this whole package around is an Ultradyne solid roller from Bullet Racing Cams that specs out with 255/264 degrees of duration at 0.050-inch tappet lift and 0.686/0.680-inch valve lift based on a rocker ratio of 1.7:1. Bullet also supplied the roller valvesprings to keep everything happy at speed, while a Cloyes timing set spins the cam using Comp pushrods.
Heads: Big ports are necessary to feed a hungry 548ci Rat motor, so the nod went to World Products for a set of Merlin 320cc iron castings. After friend Larry Martin revived the castings with some judicious port work and a solid valve job, the 2.30/1.88-inch stainless steel valves improved the flow dramatically.
Induction: World Products also supplied the 4150-style Merlin single-plane intake manifold that mounts a Pro Systems- modified Holley that now flows right around 1,000 cfm of air filtered by a K&N air-cleaner assembly. All that cfm is really necessary when you're making in excess of 750 hp. The 2-inch open plenum spacer also helps the air and fuel transition between the carburetor and the heads. As for spark, Tom relies on an MSD Digital 6 with total timing set at 36 degrees.
Exhaust: Jet Hot coated a set of 211/48-inch headers for the Chevelle, and they are hooked to stainless steel pipes that lead to a pair of Flowmaster mufflers
Trans: When you're packing 548 cubes, you also need the strength of a Turbo 400 built by buddy Tom Oermann, who added some extra clutches, beefed the internals, and added a complete reverse-pattern manual valvebody. Tom then added a Trans Specialties 9-inch converter with a 3,000-rpm stall speed, just to make the car a little more streetable. Tom controls the trans with a B&M Pro Ratchet shifter.
Rearend: "I wanted a 9-inch no matter what," Tom says. He found a housing out of a '70 Mustang that was the same width as the original 10-bolt. Tom did his own conversion, welding the original lower control arm mounts off the old 10-bolt onto the 9-inch and fabricating his own upper mounts using a jig he made himself. Then he had a local shop assemble the 3.50 gears with a spool and Dutchman 31-spline axles. Driveshafts Unlimited in Arnold, Missouri, built the chrome-moly steel driveshaft. Tom also added rear shocks from Summit along with Air Lift airbags inside the coil springs to help the launch with a little preload.
Brakes: Here's where a basic '70 Chevelle front disc-brake conversion is simple and easy for the front. At the rear, Tom went with a pair of discs from an '88 Mercury Grand Marquis that offer a streetable parking-brake setup with a mini-drum inside the rear rotors similar to the Ford Explorer rear disc-brake system.