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The valvetrain consists of all the components responsible for transferring the rotational movement of the camshaft into the opening and closing of the intake and exhaust valves. Typical components are listed below in order from the crankshaft to the valves.
53:. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) into the combustion chamber, while the exhaust valves control the flow of spent exhaust gases out of the combustion chamber once combustion is completed.
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are long, slender metal rods that are used in overhead valve engines to transfer motion from the camshaft (located in the engine block) to the valves (located in the cylinder head). The bottom end of a pushrod is fitted with a
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145:, upon which the camshaft makes contact. The camshaft lobe moves the lifter upwards, which moves the pushrod. The top end of the pushrod pushes on the rocker arm, which opens the valve.
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The valvetrain layout is largely dependent on the location of the camshaft. The common valvetrain configurations for piston engines, in order from oldest to newest, are:
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have also been used at times. Poppet valves are typically opened by the camshaft lobe or rocker arm, and closed by a coiled spring called a
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overhead valve engine. The rocker cover has been removed, so the pushrods, rocker arms, valve springs, and valves are visible.
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169:. Overhead camshaft engines use fingers or bucket tappets, which are actuated from above directly by the cam lobes.
165:. Overhead valve engines use rocker arms, which are actuated from below indirectly (through the pushrods) by the
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occurs when the valve spring is unable to control the inertia of the valvetrain at high engine speeds (RPM).
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114:, through use of a carefully shaped lobe on a rotating shaft. The camshaft is driven by the
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is a mechanical system that controls the operation of the intake and exhaust valves in an
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and, in the case of a four-stroke engine, rotates at half the speed of the crankshaft.
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Motion is transferred from the crankshaft to the camshaft most commonly by a rubber
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92:: The valves and camshafts are in the cylinder head above the combustion chamber.
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The timing and lift profile of the valve opening events are controlled by the
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82:: The camshaft remains in the block, however the valves are located in the
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How to Build and Modify
Chevrolet Small-Block V-8 Camshafts and Valves
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282:"What is the difference between OHV, OHC, SOHC and DOHC engines?"
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Depending on the design used, the valves are actuated by a
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The Cars of
American Motors: An Illustrated History
18:Mechanical system in an internal combustion engine
68:: The camshaft and the valves are located in the
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346:. Motorbooks International. p. 114.
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458:Crankcase ventilation system (PCV valve)
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260:"Sci-Tech Dictionary: "valvetrain""
149:Rocker arm / Finger / Bucket tappet
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1054:Engine valvetrain configurations
236:Brain, Marshall (5 April 2000).
560:Overhead valve (pushrod) layout
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86:above the combustion chamber.
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401:Internal combustion engine
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51:internal combustion engine
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869:Diesel particulate filter
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821:Idle air control actuator
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762:Engine control unit (ECU)
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312:. McFarland. p. 80.
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934:Viscous fan (fan clutch)
846:Throttle position sensor
555:Overhead camshaft layout
306:Cranswick, Marc (2011).
177:Most modern engines use
90:Overhead camshaft engine
473:Core plug (freeze plug)
340:Vizard, David (1992).
238:"How Car Engines Work"
42:
30:
218:Camless piston engine
80:Overhead valve engine
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714:Compression ignition
864:Catalytic converter
129:or a set of gears.
990:Knocking / pinging
582:Combustion chamber
74:combustion chamber
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25:Cutaway of a dual
1059:Engine components
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1005:Stratified charge
772:Electrical system
754:Engine management
587:Compression ratio
527:Starter ring gear
426:rotating assembly
27:overhead camshaft
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879:Exhaust manifold
744:Spark plug wires
630:Boost controller
617:Forced induction
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66:Flathead engine
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899:Cooling system
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681:Fuel injection
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734:Ignition coil
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666:Petrol engine
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661:Diesel engine
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625:Blowoff valve
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542:Cylinder head
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433:Balance shaft
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262:. Answers.com
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191:rotary valves
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183:sleeve valves
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179:poppet valves
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125:, a metallic
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84:cylinder head
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919:Electric fan
719:Coil-on-plug
645:Turbocharger
640:Supercharger
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512:Main bearing
502:Firing order
492:Displacement
438:Block heater
422:Engine block
410:Part of the
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357:. Retrieved
342:
335:
323:. Retrieved
308:
301:
289:. Retrieved
285:
276:
264:. Retrieved
254:
242:. Retrieved
231:
213:Cam-in-block
199:
195:valve spring
194:
187:slide valves
176:
161:, or bucket
152:
136:
127:timing chain
126:
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109:
100:
70:engine block
60:
46:
44:
15:
943:Lubrication
907:Air cooling
724:Distributor
676:Fuel filter
654:Fuel system
635:Intercooler
602:Timing belt
592:Head gasket
522:Piston ring
201:Valve float
181:, although
123:timing belt
1049:Valvetrain
1043:Categories
995:Power band
955:Oil filter
929:Thermostat
874:EGT sensor
836:MAF sensor
831:MAP sensor
816:Air filter
780:Alternator
739:Spark plug
671:Carburetor
597:Rocker arm
537:Valvetrain
468:Crankshaft
412:Automobile
359:29 January
325:29 January
291:23 January
266:29 January
244:29 January
224:References
155:rocker arm
116:crankshaft
97:Components
72:below the
47:valvetrain
729:Glow plug
691:Fuel tank
686:Fuel pump
453:Crankcase
167:cam lobes
112:camshafts
1028:Category
973:Dry sump
969:Wet sump
960:Oil pump
924:Radiator
841:Throttle
701:Ignition
572:Camshaft
497:Flywheel
478:Cylinder
463:Crankpin
207:See also
138:Pushrods
106:Camshaft
1000:Redline
884:Muffler
785:Battery
709:Magneto
133:Pushrod
1023:Portal
811:Airbox
790:Dynamo
517:Piston
507:Stroke
486:layout
414:series
350:
316:
173:Valves
163:tappet
159:finger
143:lifter
57:Layout
39:AMC V8
29:engine
983:Other
607:Valve
577:Chest
37:1969
965:Sump
482:bank
443:Bore
361:2014
348:ISBN
327:2014
314:ISBN
293:2020
268:2014
246:2014
189:and
950:Oil
539:and
424:and
197:.
1045::
971:,
484:,
284:.
185:,
157:,
45:A
975:)
967:(
488:)
480:(
393:e
386:t
379:v
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329:.
295:.
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248:.
76:.
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