The camshaft.whether in a pushrod or an overhead cam engine.does the job of controlling the closing and opening of the valves to regulate the flow of fuel and air into and out of the engine. With such task, the camshaft proves to be crucial in improving the engine's performance as well as the vehicle's emissions and fuel economy. So as soon as it necessitates replacement, you should spend time looking for and choosing the right camshaft.
For those who need a performance camshaft, keep some dos and don'ts to keep in mind.
Do pick the camshaft with the right profile.
Much like other auto components, you have lots of camshaft choices to select from, particularly if your ride's engine is popular. However, each camshaft type has specific recommendations, so it's best to get the advice of the camshaft supplier. If your sole purpose is to restore the engine's original performance, it is wise to get a stock replacement or a duplicate of the OEM.
If you want to boost engine performance, you should go for cams with enhanced profiles. But, be ready as the process of choosing becomes more complicated. When choosing such camshafts, you have to consider the goal you have in mind, the vehicle's weight, the type of transmission your vehicle comes equipped with, as well as its drive gear ratios. Cams with enhanced profiles include towing cams, mileage cams, and performance cams. With these cams, your vehicle's emissions, idle quality, and drivability won't change, but the engine will give off more power and achieve better fuel mileage.
Do consider the camshaft specifications.
Among the camshaft specs that you have to take into consideration are overlap, timing, durations, lift, and lobe separation. The valve lift is the distance the valves open. Increasing the valve lift means allowing more fuel and air to get into the cylinders. Meanwhile, duration is the period the cam is able to keep the valves open. By getting the cam's duration, you'll be able to gauge its ability to generate power within a particular rpm range. The longer the duration, the higher the cam's operation range is.
The relative timing of the exhaust and intake valves should also be considered as it affects valve overlap, which happens when the intake valve starts to open before the exhaust valve closes. Increasing the overlap is helpful in higher RPM performance applications. OEM cams also need more overlap to produce EGR effect and trim down NOX emissions.
Do make the right choice between a flat tappet and a roller cam.
To make your choice easier, you have to consider the kind of engine you have or are building. For a high-rev performance engine, a flat tappet cam featuring solid lifters will deliver maximum rpm without valve float. Lower RMP or street performance engines, on the other hand, will benefit more from a roller cam fitted with hydraulic filters as such cam is made to generate lots of toque.
Don't over-cam your engine.
When selecting a cam, make sure you won't "over-cam" your engine. A hot cam installed in a stock engine can result in component mismatch, which will just end up hurting rather than improving the engine's performance. A long duration cam, if used inappropriately or in incompatible applications, will just cause emission problems.
Don't overlook the camshaft timing.
Cam timing is also something that shouldn't be ignored when choosing a camshaft, especially one for a performance engine rebuild. Don't assume that as long as the timing marks on the cam drive are properly lined up, the engine's cam timing is correct. While this is fine with a stock cam, it may not be good enough for performance engines. Remember that cam timing directly affects engine performance, so make sure that it is accurate.