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The Curious Bag
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The long block is the largest sub-assembly in a vehicle's engine. It forms the foundation for the engine's intake and exhaust systems, as well as the accessories.
Parts
The long block is composed of the engine block, rotating assembly and cylinder head or heads. Camshafts may not be included in the long block, depending on whom you ask.
Short vs. Long Block
A short block is a sub-assembly of a long block. The only difference between the two is that a long block comes with the cylinder heads already installed and a short block doesn't.
Cylinder Heads
A cylinder head caps off the top of the engine block and contains the valve-train. It also houses the cam or cams on overhead-cam engines.
Valve-Train
The valve-train consists primarily of a set of valves and actuators, which are springs and levers required to open and close the valves.
Camshafts
Push-rod engines have one cam in the center of the block, and overhead-cam heads carry one to three cams per cylinder head. In either case, camshafts indirectly open the valves via a set of levers, or rocker arms and springs inside each cylinder head.
Source:
Resource:
Crate Long Block
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