Editing Overhead valve engine (section)

== Design ==
[[File:pushrod engine.jpg|thumb|right|upright=0.8 |[[V8 engine]] (with intake manifold removed), showing the camshaft, pushrods, and rockers]]

OHV engines have several advantages compared with OHC engines:
* '''Smaller overall packaging:''' The [[cam-in-block]] design of an OHV engine results in a smaller overall size, compared with an equivalent OHC engine, which can have some advantages in center of gravity and hood height in V-engine designs.<ref name=Webster2004>{{Cite web |url= http://www.caranddriver.com/features/04q2/the_pushrod_engine_finally_gets_its_due-column|title= The Pushrod Engine Finally Gets its Due|first= Larry|last= Webster|date= May 2004|website= [[Car and Driver]]|access-date= 31 December 2014|url-status= live|archive-url= https://web.archive.org/web/20140826193302/http://www.caranddriver.com/columns/the-pushrod-engine-finally-gets-its-due|archive-date= 26 August 2014}}</ref>
* '''Simpler camshaft drive system:''' OHV engines have a less complex drive system for the camshaft than [[OHC]] engines.<ref name=Webster2004 /> Most OHC engines drive the [[camshaft]] or [[camshaft]]s using a [[timing belt (camshaft)|timing belt]], a [[roller chain|chain]], or multiple chains. These systems require the use of [[tensioner]]s, which add complexity. In contrast, an OHV engine has the camshaft positioned close to the crankshaft, which may be driven by a much shorter chain or even direct gear connection. However, this is somewhat negated by a more complex valvetrain requiring pushrods.
* '''Simpler lubrication system:''' The lubrication requirements for OHV cylinder heads are much lower, as they typically have a single camshaft within the block, where an OHC engine can have two per bank of cylinders, requiring oil passages through the cylinder head. OHV heads only need lubrication for the rocker arms at the pushrod end, [[trunnion]], and rocker tip. This lubrication is typically provided through the hollow pushrods themselves rather than a dedicated lubrication system in the head. The reduced lubrication requirements can also mean that a smaller, lower-capacity oil pump is used.

Compared with OHC engines, OHV engines have the following disadvantages:
* '''Limited engine speeds:''' Although OHV engines have simpler drive systems for the camshaft, there are a greater number of moving parts in the [[valvetrain]] (i.e., the lifters, pushrods, and rockers). Inertia from these valvetrain parts makes OHV engines more susceptible to [[valve float]] at high engine speeds (RPM).<ref name="howstuffworks1" />
* '''Constraints on valve quantity and location:''' In OHV engines, the size and shape of the intake ports as well as the position of the valves are limited by the pushrods and the need to accommodate them in the head casting.  As a result, it is rare for an OHV engine to have more than two valves per cylinder, while OHC engines often have four, allowing for higher rates of combustion and exhaust.<ref>{{cite web |title=What is the difference between OHV, OHC, SOHC and DOHC engines? |url=https://www.samarins.com/glossary/dohc.html |website=www.samarins.com |access-date=19 December 2019}}</ref>