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Video: Edelbrock/Musi 24-degree BBC Heads Dyno Tested

It’s not that engine building is becoming as simple as assembling an Ikea entertainment center right out of the box, but much of the work today is being handled by CNC machines and expert development.

Edelbrock recently posted a dyno video of a 555ci, single 4-barrel big-block Chevy built by the Vrbancic Bros. out of Ontario, California. It pulled a stout 903 horsepower with just 9.2:1 compression ratio. With the exception of a proprietary solid roller camshaft and a little massaging of the intake manifold, the engine was pretty much off-the-shelf ready-to-go.

“We wanted to make as close to a bolt-on deal as possible,” says Bob Vrbancic, noting the engine will get an F2 Procharger and run in the Top Sportsman class but the shop wanted to get in a stress-free baseline run.

The Edelbrock/Musi 24-degree heads are available either bare (PN 61419) or assembled (PN 61409)

The short block is comprised of a Merlin block bored to 4.560-inch and fitted with a Callies 4.250-inch-stroke crankshaft, Oliver rods and Diamond pistons. A Moroso billet pump with 7-quart pan provide lubrication. Key to the performance potential is the Edelbrock top-end combo of 24-degree Musi/Victor CNC-ported cylinder heads (PN 61419 bare, PN 61409 assembled) and a Super Victor intake manifold (PN 2917). The cylinder heads were bolted on right out of the box while the intake manifold was flow tested and then port-matched to the intake gasket. A Carb Shop-prepped Holley Dominator carb was used for the initial test, then a Carb Shop billet unit was swapped on for the supercharged version.

The Super Victor CNC intake is machined by Reher-Morrison Racing Engines.

“With the F2 it made 1,640 horsepower at 19 pounds of boost,” says Vrbancic.

The cylinder heads were developed along with noted engine builder and racer Pat Musi, starting with Edelbrock’s 24-degree A356 aluminum casting that is heat treated to T6 specs. The exhaust ports are raised .750-inch, and extra material is added to the deck and spring pockets for improved durability. The ports are the CNC machined to Musi’s specs, resulting in 119cc combustion chamber and 367/377cc intake runners. Although the head is available bare, Vbrancic used a set that came assembled with 2.300/1.900 stainless-steel valves, Manley springs and titanium retainers. Vrbancic added the Jesel 1.75/1.70 rockers.

The manifold is a special version of the Super Victor intake and is CNC machined by Reher-Morrison Racing Engines in all the critical areas, including plenum, port exits, divider walls and runner roofs. Edelbrock also offers a tall-deck model.

About the author

Mike Magda

Mike Magda is a veteran automotive writer with credits in publications such as Racecar Engineering, Hot Rod, Engine Technology International, Motor Trend, Automobile, Automotive Testing Technology and Professional Motorsport World.
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