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Valve seats are often formed by first press-fitting an approximately cylindrical piece of a hardened metal alloy, such as Stellite, into a cast depression in a cylinder head above each eventual valve stem position, [1] and then machining a conical-section surface into the valve seat that will mate with a corresponding conical section of the ...
The upper part of the valve stem, within the rocker box, is lubricated by oil. If this oil travels unchecked along the valve stem, engine HC emissions will become excessive. To control this, an elastomeric seal is fitted over the top of the valve guide. These may wear or stiffen with age, so are usually replaced whenever valves are removed for ...
Long block - a short block, with mounted and gasketed cylinder head, valves and camshaft; Crate engine - a new or remanufactured engine, considered to be equivalent to a new engine. [3] Parts include more than a long block, including intake manifold, and carburetor or fuel injection system, oil pan, valve covers, and perhaps an alternator
Although this provides better heat transfer, it requires steel valve seat inserts to be used; in older cast iron cylinder heads, the valve seats are often part of the cylinder head. A gap of 0.4–0.6 mm (0.016–0.024 in) is present around the valve stem, therefore a valve stem oil seal is used to prevent oil being drawn into the intake ...
A tappet or valve lifter is a valve train component which converts rotational motion into linear motion in activating a valve. It is most commonly found in internal combustion engines , where it converts the rotational motion of the camshaft into linear motion of intake and exhaust valves, either directly or indirectly.
The lower half of the main bearings are typically held in place by 'bearing caps' which are secured to the engine block using bolts. The basic arrangement is for each bearing cap to have two bolts, but some engines may have four or six bolts per bearing cap (often referred to as "four-bolt mains" or "six-bolt mains" engines).
A hydraulic tappet, also known as a hydraulic valve lifter or hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. Conventional solid valve lifters require regular adjusting to maintain a small clearance between the valve and its rocker or cam follower .
In 1936 and 1937, the Indian Four had the valve positions reversed, with the exhaust valve in the head and the inlet valve in the block. In theory, this would improve fuel vaporization, and the engine was actually more powerful. However, the new system made the cylinder head very hot. The exhaust valve linkage required frequent adjustment.