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Connecting rods are subject to massive forces. At 4,000 rpm, the pistons an engine with a four-inch stroke and a connecting rod length of 5.91 inches will accelerate and decelerate with a force equal to over 640 times the force of gravity. The connecting rods must be up to the task of controlling these forces several hundred times per second without bending, breaking or doing anything unexpected. Connecting rod dimensions and construction can make the difference between a reliable racer and one that self destructs at the first sign of abuse.
Four-Cylinder Engines
The Chevrolet 2.2Ls — also known as the Vortec 2200 — rods have a center-to-center (c-c) length of 5.590 inches, weigh 530 grams and utilize 0.31-inch rod bolts. The Chevrolet/Oldsmobile Quad Fours rods are 5.710 c-c, weigh 530 grams and use 5/16-inch rod bolts. The newest generation Ecotec 2.2Ls rods are 5.765 c-c, weigh 550 grams and use 0.31-inch (5/16-inch) rod bolts.
Six-Cylinder Engines
The Chevrolet 250 straight six uses rods measuring 5.7 inches c-c, with a 2.00-inch crankshaft pin and 9.27-inch wrist pin diameter and weigh 680 grams. The 4.3L Vortecs — and earlier 262 V-6 — rods are 5.7 inches c-c with a 2.25-inch crankshaft pin and a 9.27-inch wrist pin, and weigh 665 grams.
Small Block V-8s
The 327 and 350 small blocks use rods measuring 5.7 inches c-c with a 2.1 inch crankshaft pin and a 0.927 wrist pin, and weigh in at 630 grams. The larger 400 small blocks rods are identical but for their 5.565-inch c-c length. Small block 283 rods measure 5.7 inches c-c, 2.00 inches on the crankshaft end and 0.927 inches on the wrist pin and weigh 655 grams. The newest generation LS1 small block 350 uses powdered metal connecting rods weighing 650 grams with a c-c length of 6.1 inches and a wrist pin diameter of 0.927 inches.
Big Block V-8s
All big blocks measuring from 396 to 502 cubic inches in displacement use 6.135-inch c-c rods weighing 780 grams and measuring 2.2 inches at the crankshaft pin and 0.999 inches at the wrist pin.
