4.3 Vortec Torque Specs

by Anne Davis
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General Motors manufactures a line of Vortec engines, including the 4.3 liter. These engines are so-called because they use "vortex technology," creating a vortex within the engine's combustion chamber. This technology achieves a better mixture of air and fuel during the combustion process, making them more powerful and efficient. The 4.3-liter V6 is similar to the 350-cubic-inch displacement small-block V8, except that it has only two oil galleries, while the 350 has three.


A vehicle's engine block, usually constructed of cast iron, is a collective term referring to the engine's crankcase and associated components; it provides the power for the vehicle. In 4.3-liter V6 engines manufactured before 1995, the crankshaft bolted to the engine block with 75 foot-pounds of torque; in those built in 1995, the two join with 81 foot-pounds; in engines built after 1995 and until 1998, they attach with 77 foot-pounds; and in those built in or after 1999, the crank bolts to the block with 15 foot-pounds. The flywheel-to-crankshaft bolts require 75 foot-pounds of torque. The vibration damper, also known as the hub, attaches to the crankshaft with 70 foot-pounds of torque.

Cylinder Head

In engines built before 1996, the cylinder head bolts require 65 foot-pounds of torque; in those built in or after 1996, the same bolts require 22 foot-pounds. The exhaust manifold bolts to the cylinder head first with 11 foot-pounds of torque, then with 22 foot-pounds. The lower front bolts of the intake manifold in pre-1996 engines require 35 foot-pounds, the lower rear bolts require 41 foot-pounds, and the upper bolts require 10 foot-pounds of torque. In engines made after 1995, the intake manifold bolts to the cylinder head first with 2 foot-pounds, then with 9 foot-pounds and finally with 11 foot-pounds of torque.

Oil Pan and Pump

The bolts of the oil pan in engines manufactured before 1996 require 8.33 foot-pounds and the nuts require 17 foot-pounds of torque to join with the engine block. In engines made from 1996 until 1998, the bolts require 17 and the nuts require 18 foot-pounds of torque. After 1998, the nuts and bolts of the oil pan attach to the engine block with 18 foot-pounds of torque. The drain plug attaches to the oil pan with 18 foot-pounds of torque. The engine's oil pump requires 65 foot-pounds of torque to bolt to the engine block.

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