July '20

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58 THE SHOP JULY 2020 JULY 2020 Racing to Help p.66 Engine Products p.68 PRECISION ENGINE E D I TO R ' S N OT E : T h i s i s t h e first in a multi-part series of arti- cles detailing the build of a 422-ci small-block Chevrolet Gen 1 engine. H ere we'll provide an overview of a specific build, based on the small- block Chevrolet Gen 1 format, but using 100% aftermarket performance components. As you know, variances based on the SBC have been done countless times. This project is simply another approach to building a street/race engine, since the Gen 1 SBC remains a popular choice for many builders—even with the surge in popularity of later-generation formats such as the LS and LT/LT4 series. In a nutshell, this build involves a Dart SHP PRO Iron block with cylinders sized to 4.1642 inches, Trick Flow 18-degree cylinder heads, ARP fasteners throughout, ICON flat-top forged pistons, 6.000-inch SCAT forged H-beam rods, SCAT forged crankshaft with a stroke of 3.875 inches, Morel solid roller lifters, COMP Cams billet solid roller camshaft, Jesel 1.6:1 offset roller rocker system, Fel-Pro gaskets, MAHLE Clevite main and rod bearings, Melling oil pump, Jesel camshaft belt drive, Trend pushrods, Dart single-plane intake manifold designed for 18-degree heads, Meziere electric water pump, MSD Pro Billet distributor, MSD crank trigger, Holley 850-cfm carburetor, MSD 8mm spark plug wires, Moroso oil pan, Moroso valve covers and Fluidampr 6.250-inch crankshaft balancer. The compression ratio was finalized at 13.557:1. The engine ultimately produced 735 hp at 7,100 rpm and 575 pound-feet of torque at 6,250 rpm. BLOCK PREP The Dart iron block selected for this build can be bored and honed to accept 4.125- inch bores, and can safely be sized to 4 . 1 6 5 i n c h e s while main- taining suffi- cient cylinder wall thickness. In this case, since our 18-degree cylinder heads require a minimum bore size of 4.155 inches (for adequate valve-to-block deck clearance), we opted for the larger 4.165-inch bore size. Prior to machining, we test-fitted the crankshaft in order to check counterweight clearance to the block's pan rails, and rods were test- fitted to check for rod big end clearance. As we've done in the past with Chevy projects, block machining was performed by Scott Gressman of Gressman Power- sports in Fremont, Ohio, on the shop's dedicated engine block CNC machine. The block was delivered with a raw deck height of 9.027 inches. In order to achieve zero deck with pistons at TDC, our decks were milled to achieve a finished deck height of 8.9995 inches (stock deck height for a small-block Chevy is 9.025 inches). This was determined by factoring in our crankshaft stroke, connecting rod length and piston compression distance. Another go-round building a tried-and-true Gen 1 small-block Chevy. COMPRESSION RATIO OF OUR 422-CI SMALL-BLOCK BUILD: BORE 4.1642 STROKE 3.875 PISTON CD 1.062 GASKET BORE 4.200 GASKET THICK 0.052 ROD LENGTH 6.000 CHAMBERS 56 cc STATIC COMPRESSION RATIO: 13.557:1 58 THE SHOP JULY 2020 Back to Basics My block of choice for this build is Dart's SHP PRO Iron block, P/N 31161212, an example of a vast improvement over the original Chevy design in terms of strength, oil delivery and accommodation of increased bore and stroke. By Mike Mavrigian

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