An essential and complex engine component, the camshaft is a difficult automotive part for many consumers to understand. Selecting the right camshaft involves having a clear understanding of its performance and how it relates to the internal combustion engine. By getting to know the camshaft in better detail, vehicle owners are more likely to find the right match for their car or truck and get the most out of their vehicle's performance.
How camshafts work
A camshaft is a metal shaft to which individual components known as cams are attached. As the camshaft rotates, the cams' movement allows the intake and exhaust valves in an engine to open and close in turn. The cams are typically lobe-shaped so that they both push against and then pull away from the valves during rotation.
Camshaft performance specs
When selecting a camshaft, vehicle owners need to keep several important technical specs in mind. These issues directly affect the performance of the part and, by extension, the engine.
The duration of a camshaft defines how long it keeps each valve open as it rotates. If a camshaft has a high duration rate, it keeps the valves open longer, letting more air and petrol into the engine but also releasing more gasses through the exhaust. A lower duration rate does the opposite. Manufacturers express this rate as a degree of the crankshaft rotation, such as 280 degrees of duration.
Camshafts with a higher degree of duration typically have less torque at low RPMs but more power at the top end. Lower degrees of duration deliver more torque at lower speeds and also tighten up idling.
The lift measurement of a camshaft, represented in millimetres or inches, defines how high off the seat a camshaft lifts a valve. The higher the lift, the more power that engine can produce. It is important, however, to keep lift within safe limits for an engine. Staying below 12.7 mm of lift is ideal for a standard engine.
Overlap or lobe separation angle
Overlap, often referred to as lobe separation angle, defines the length of time both intake and exhaust are open at the same time during the rotation of a camshaft. Overlap is defined as the relationship in degrees between the intake and exhaust lobes at the moment when they are both wide open. A lower lobe separation angle of 106 degrees as compared to 110 degrees results in more overlap. More overlap, or a lower lobe separation angle, results in a looser and chokier throttle. The upside is that the engine can typically produce more power at the mid and high range.
Types of camshafts
With these specs in mind, consumers should also understand the different types of camshafts available. Design differences can impact a camshaft's performance significantly and its applicability to specific vehicles.
Hydraulic lifter and solid lifter camshafts
The two main categories of camshafts are hydraulic lifter cams and solid lifter cams. Hydraulic lifter camshafts are the easiest solution for family and commuter vehicles, as they require no adjustments. Solid lifter cams require regular lash adjustments but deliver much more power in high-RPM applications and are a go-to choice for racers and performance vehicles.
Roller and flat tappet camshafts
Within the larger categories of hydraulic and solid lifter camshafts, consumers can find both roller and flat tappet camshafts. Hydraulic roller camshafts are the most common type found in OEM factory engines. Hydraulic flat tappet camshafts are often more economical and offer quiet performance. Both solid and hydraulic roller camshafts are typically more assertive, performance choices that deliver more RPMs.
Single vs. dual pattern camshafts
A single pattern camshaft uses the same lift or duration for both the intake and exhaust valve. A dual pattern camshaft, on the other hand, uses different rates for the intake valve and the exhaust valve, typically bestowing more lift and duration to the exhaust. Dual pattern camshafts are optimal for vehicles with restricted or poor performing exhaust systems.
How to buy camshafts on eBay
Vehicle owners can browse a large variety of camshafts on eBay. Begin by performing a keyword search for the camshaft you want. If you enter a general term, such as "camshaft", you can review a large range of products, but you can also perform a more specific search, such as "solid roller camshaft", which returns a shorter list of results. A camshaft is an essential yet complicated performance component, but with some basic knowledge anyone can search for the right fit.