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. The assembly process for our project engine included all of the balancing and blueprinting 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 blockDart's 310cc aluminum Pro1 cylinder headsEagle 4340-forged crankshaftEngine Pro H-beam connecting rodsJE pistonsComp Cams hydraulic roller camshaft and rocker armsDart single-plane intake manifoldDemon 850cfm carburetor 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. With bearing-to-crank specs within the acceptable range, the heavy-duty forged crankshaft 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. After the crankshaft is in place, the main caps are installed and torqued to spec. A tip we picked up at the Dart assembly facility was using CMD's Extreme Pressure Lube (www.cmdlube.com) on the threads instead of a light coat of simple motor oil. This industrial-grade lubricant doesn't break down under extreme pressure, ensuring a lubricated film on the threads even as the bolts are torqued to 105 pounds. After the crankshaft is in place, the main caps are installed and torqued to spec. A tip w Our precision engine uses Hastings file-fit piston rings, which were first positioned in the bores and their gaps measured with a feeler gauge. We were looking for gaps of 0.020-inch A few moments with the ring file did the trick and the rings were installed on the pistons. Our precision engine uses Hastings file-fit piston rings, which were first positioned in t A set of forged steel Engine Pro H-beam connecting rods was selected. H-beam rods typically offer lower mass than I-beam rods, enhancing the rev capability of our big-bore/short-stroke combination through reduced inertia. Each measures 6.135 inches in length and weighs about 790 grams. They'll be used with floating pins. A set of forged steel Engine Pro H-beam connecting rods was selected. H-beam rods typicall JE forged aluminum pistons are used in our Dart 509 engine. There are no exotic features, custom pin height specifications or anything like that, just the basic, durable forging. The stock, 4.000-inch stroke minimizes the pistons' travel within the cylinders, which reduces the drag from the rings. That frees up horsepower and enhances the rev range. JE forged aluminum pistons are used in our Dart 509 engine. There are no exotic features, With the set of JE forged aluminum pistons mounted to the Engine Pro rods, the piston/rod assemblies are carefully installed in the cylinder block. The low-dome pistons are simple, off-the-shelf products that will work with a set of Dart's aluminum cylinder heads to deliver a compression ratio of about 10.25:1-plenty of squeeze to help create big horsepower, yet with pump gas drivability. With the set of JE forged aluminum pistons mounted to the Engine Pro rods, the piston/rod Here's the assembled short-block, similar to the production versions offered by Dart. In the wrap-up installment of this story, we'll add the cam, heads and induction system to see how close our 509-inch big-bore Rat comes to the 668 hp dyno performance predicted by Dart. Here's the assembled short-block, similar to the production versions offered by Dart. In t SOURCES Dart Machinery 2-48/-362-1188 www.dartheads.com « | 1 | 2 | View Full Article By Barry Kluczyk Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!