Editing Overhead camshaft engine (section)

=== Single overhead camshaft (SOHC) {{anchor|SOHC}} ===
<!-- This section is linked from [[Inline-four engine]] -->
[[File:Dolomite Sprint Valves Section.jpg|thumb |SOHC design (for a 1973 [[Triumph_slant-four_engine#Sprint_16-valve_engine|Triumph Dolomite Sprint]]) ]]

The oldest configuration of overhead camshaft engine is the ''single overhead camshaft'' (SOHC) design.<ref name=Hillier/> A SOHC engine has one camshaft per bank of cylinders, therefore a [[straight engine]] has a total of one camshaft and a [[V engine]] or [[flat engine]] has a total of two camshafts (one for each cylinder bank).

Most SOHC engines have 2 valves per cylinder (sometimes 3 or 4), 1 intake valve and one exhaust valve.{{efn-la|However a few engines, such as the 1973 [[Triumph_slant-four_engine#Sprint_16-valve_engine|Triumph Dolomite Sprint engine]] and [[Honda_J_engine | Honda J Series V6 Engine]] were/are a SOHC configuration with four valves per cylinder. This was achieved by the camshaft being located in the center of the cylinder head, with equal length rocker arms actuating the intake and exhaust valves.<ref>{{cite journal|last= Heseltine|first= Richard|title= Triumph Dolomite Sprint|journal= [[Motor Sport (magazine)|Motor Sport]]|date= June 2010|volume= 86|issue= 6|page= 122|editor-last= Roebuck|editor-first= Nigel|issn= 0027-2019|location= London, UK|url= https://www.motorsportmagazine.com/archive/article/june-2010/122/triumph-dolomite-sprint|access-date= 29 March 2015}}</ref> This arrangement was used to provide four valves per cylinder while minimising the valvetrain mass and minimising the overall engine size.<ref>{{Cite journal|last= Lewis|first= Jimmy|title= New for '02: Honda CR250R CRF450R|journal= [[Cycle World]]|page= 62|date= November 2001|volume= 40|issue= 11|editor-last= Edwards|editor-first= David|issn= 0011-4286|publisher= Hachette-Filipacchi Magazines|url= {{Google books|NKRYLxEd6uAC|Cycle World Magazine Jan-Jul 2001|page=RA12-PA62|plainurl=yes}}|access-date=2 January 2015}}</ref><ref>{{Cite web|url= http://powersports.honda.com/experience/articles/090111c0811a9fc2.aspx|title= How It Works: Honda Unicam® Engines|website= www.honda.com|date= 23 January 2013|access-date= 2 January 2015|url-status= dead|archive-url= https://web.archive.org/web/20140222215132/http://powersports.honda.com/experience/articles/090111c0811a9fc2.aspx|archive-date= 22 February 2014}}</ref><ref>{{Cite web |url= http://www.moto123.com/motorcycle-reviews/article,2010-honda-vfr1200a-first-ride.spy?artid=112508|title= 2010 Honda VFR1200A First Ride |website=www.moto123.com |access-date= 2 January 2015|date= 19 October 2009|url-status= live|archive-url= https://web.archive.org/web/20150102212534/http://www.moto123.com/motorcycle-reviews/article,2010-honda-vfr1200a-first-ride.spy?artid=112508|archive-date= 2 January 2015}}</ref>}} Motion of the camshaft is usually transferred to the valves either directly (using a tappet) or indirectly via a [[rocker arm]].<ref name=Hillier/>