Mustang Camshaft Facts & Technical Information
Mustang Camshaft Facts & Technical Information
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Whether you're looking for performance, sound, or both, new camshafts will have you grinning from ear to ear. Huge performance gains and a totally new sound are the two main reasons to purchase new cams for your Mustang.
One of the most crucial parts of an engine is the camshaft. This guide will serve to inform you on how camshafts function in different engine layouts.
What Are Mustang Camshafts?
A camshaft is a component that controls the opening and closing of the intake and exhaust valves. By making adjustments to the timing, length of time valves are open, and how far the valves open, you control the power band of a motor. There are three common types of camshaft configurations seen today, and the Mustang has seen all three of them used in its engines in the last couple of decades.
- Overhead Valve (OHV)—the camshaft is placed in the engine block, and pushrods (hence "pushrod" motors) transfer the motion of the rocker arms to open and close the valves in the head
- Single Overhead Cam (SOHC)—the camshaft is placed at the top of the engine head and has less parts involved
- Dual Overhead Cam (DOHC)—the camshaft is essentially the same as SOHC, but contains two camshafts in each head
Overhead Valve Cams
The overhead valve (OHV) configuration is becoming less common. In this configuration, the camshaft is placed in the engine block, and pushrods transfer the motion of the camshaft to rocker arms that open and close the valves. Since the camshaft is below the valves what with the valves higher up and above the pistons, we get the term "overhead valve". As the camshaft rotates, lifters ride on the camshaft lobes which raise the pushrods. As the pushrods rise, they push one end of the rocker arm which in turn pushes the valve down and opens it.
Due to the number of components used in this type of camshaft approach, failure of the valvetrain has a higher chance than with other options. While the quality of the components used will play a factor in this, the fact remains using fewer components has a distinct advantage. In addition the overhead valve configuration is the least efficient of the three types due to the friction and mass of all the components. The last overhead valve V8 Mustang was a 5.0, used up to 1995.
Single Overhead Camshafts
SOHC stands for single overhead camshaft. It differs from the previous camshaft configuration by placing the camshaft at the top of the engine head. The camshaft is directly under the valve cover, and above the valves, giving it the overhead camshaft designation. The “single” designation comes from how one camshaft is mounted in each engine head.
The overhead configuration has a couple of distinct advantages. The first of these is the reduction of parts necessary for the camshaft to open and close the valves. The need for pushrods and lifters is eliminated, as the camshaft opens the valves by operating the rockers directly as it spins. This reduction of parts increases reliability and makes the engine’s valvetrain much more efficient. The 4.6 Liter V8 found in the Mustang GT uses a single overhead camshaft, in both the two valve versions found from 1996 to 2004 as well as the three valve versions found in the 2005 and later Mustang.
Dual Overhead Camshafts
The dual overhead camshaft (DOHC) is essentially the same configuration as the single overhead camshaft, the difference being there are two camshafts in each head as opposed to one. For engines that use four valves per cylinder, dual overhead camshafts are the preferred method of valvetrain operation because of the higher number of valves. An example of this configuration is the 32 valve engines used in the Mustang Cobra and Mustang Shelby GT500.
Mustang Camshaft Timing
Camshaft timing refers to how the camshaft operates in relation to the crankshaft. This is referred to in degrees advanced or retarded. This essentially means the valves open before or after top dead center. Performance characteristics can be altered, however, by advancing or retarding the camshafts position relative to the crankshaft. This can be a complex procedure, and an incorrect setting can cause the engine’s pistons to strike the valves.
Fixed Camshaft Timing
With fixed camshaft timing, the camshaft’s position is set when the camshaft is installed. While the overall engine timing can be altered, the camshaft’s relation to the crankshaft’s rotation will not change. This has a distinct disadvantage, in that the camshaft’s profile is going to be optimized for a somewhat narrow RPM range.
Variable Camshaft Timing
With variable camshaft timing, you will still have the positioning set when the camshaft is installed. As the engine’s RPM changes, however, the camshaft’s rotation in relation to the crankshaft can change. This makes the camshaft’s profile effective at a much greater RPM range, as the camshaft’s timing can advance and retard as needed. In the 2005 and later Mustangs, variable camshaft timing is controlled by oil pressure in conjunction with oil control solenoids and camshaft phasers. Due to the wide variation in camshaft timing allowed by the factory setup, some aftermarket camshafts require the variable timing to be limited or eliminated altogether.
Phaser Limiter Kit
When looking at a camshaft there are some terms often thrown around, and defining these terms may prove useful when shopping for a camshaft. Although basic understanding of these aspects help to tell you how the camshaft will operate, it’s always a good idea to consult the manufacturer or speed shop to get assistance in determining the best camshaft for your particular application.
- Centerline: Where the lobe hits its peak lift after opening the valve
- Duration: The degrees the valve is held open
- Lift: How far the lobe opens the valve
- Lobe Separation Angle: The degrees between the centerline of the exhaust and intake lobes
- Overlap: The degrees that both the intake and exhaust valves are open
Note: duration can be measured in two ways: from seat to seat, and valve lift. For example a 300 degree duration can be 300 degrees from valve seat to valve seat. or 300 degrees from 0.020 inches of lift to 0.020 inches of lift. In general, duration measured by valve lift is more accurate than a cam measured from seat to seat.
Forced Induction - Nitrous, Turbochargers, and Superchargers
While a comprehensive breakdown of camshaft variables and theory would take hours, one factor is very important for those going down a forced induction path. That's overlap. The less overlap you have, the less fuel and boosted air, or nitrous, escapes through the exhaust, maximizing your Mustang's power. At the same time if you're looking for top end, high RPM power some overlap is better. However you will sacrifice some power in the low end.
Several manufacturers offer cams specifically for boosted engines. They also list the individual specs such as duration, lift, and seperation angle. Another key detail is RPM range. Cams potentially have the most influence on where your Mustang makes power, and how much power your Mustang is capable of making. If you’re exploring the potential of a camshaft, examine your options carefully, and definitely make use of the manufacturers and retailers knowledge. There are plenty of options available, and getting the proper camshaft for your application will reward you with some noticeably extra horsepower.
Supporting mods for Changing Camshafts
A cam swap is the last modification that should be done to the engine. It brings all the other modifications together and had a large impact on the powerband and where it is. As a result, before people change camshaft(s), supporting mods are highly suggested. Such mods can be things like headers, an intake, a higher rear gear (such as 3.73s or 4.10s), etc.
At the same time, some modifications are needed specifically when changing camshafts. These mods are directly related to the valvetrain and include items such as valve springs or retainers. On modular (4.6 and Coyote) mustangs, camshaft sprockets and the phaser bolts must be modified or replaced in certain situations. As with any camshaft(s) swap, a tune is strongly recommended.
In a short list, here is what is suggested to change:
- Longtube headers
- Cold air intake
- Higher rear gears
- Stronger valve springs
- Aftermarket valve retainers
- New camshaft phaser bolts and phaser modifications
Fitment includes: 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, GT, V6, Cobra, ShelbyGT500, Mach1, Bullitt, Boss, LX, SVO, EcoBoost