Big Block Power Combo - Real Fine 509, Part 1

Super Chevy And Dart Machinery Set Out To Build Big-Block Power With A Big-Bore/Short-Stroke Combo.

Barry Kluczyk Nov 1, 2009 0 Comment(s)
Sucp_0911_15_z Big_block_power_combo Crankshaft_balancing 2/15

The assembly process for our project engine included all of the balancing and blueprinting processes that make for a smoother-running, longer-lasting and more powerful combination. Here, one of the Eagle crankshaft journals is mic'd and its measurement will be compared with the corresponding main bearing diameter measurement that was previously taken with a bore gauge. This is done to ensure the bearing-to-crankshaft clearance is within specifications.

With our thinking in alignment with Maskin's, we embarked on an engine-building project that would test his wisdom. We were looking for a 500-plus inch engine that would offer good dual-use duty on the street and on the drag strip. Maskin pecked out a few numbers on his calculator and a figured a 509-inch combo, with 4.500-inch bores and 454-standard 4.00-inch stroke, would do the trick.

"Based on the 400-inch SHP (Special High Performance) engines we build, it should make 668 horsepower, with all the torque you can use," he says. "It's a simple combination, too, using nothing but off-the-shelf parts."

With Maskin's recommendations, as our blueprint and his in-house engine builders our guides, we set up shop at Dart's suburban Detroit headquarters and documented the combination's assembly from the installation of the first bearing to the final pull on the engine dyno.

The basics include:
Dart's Big M iron cylinder block
Dart's 310cc aluminum Pro1 cylinder heads
Eagle 4340-forged crankshaft
Engine Pro H-beam connecting rods
JE pistons
Comp Cams hydraulic roller camshaft and rocker arms
Dart single-plane intake manifold
Demon 850cfm carburetor

Sucp_0911_11_z Big_block_power_combo Crankshaft 3/15

With bearing-to-crank specs within the acceptable range, the heavy-duty forged crankshaft is carefully installed in the cylinder block. A quick spin after it is seated ensures there are no hang-ups and spreads lubrication around the circumference of all the crankshaft journals. One of the additional benefits of the short stroke in our big-block is reduced inertia required to spin the rotating assembly. This enhances the rev capability of the engine by reducing parasitic drag.

Although our 509 engine combination seems straightforward enough, it's not something Dart stocks in its warehouse. In fact, the company doesn't sell crate engines per se, but offers a variety of short-block assemblies and the service of custom engine builds. To mirror that, we've divided this story into a pair of installments; the first focusing on the big-bore, short-stroke short-block and the second on the remainder of the engine assembly and dyno testing.

What that means is you'll see the inside of the short-block in the accompanying photos, with insight into the attributes of the Dart block that support such a generous displacement. You'll have to pick up next month's issue to see whether this Dart engine hits the bull's eye of Maskin's 668hp target.




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