Can camshafts be machined?
Camshaft core machining begins with a bar clamped in the main spindle that extends out a few inches. The lathe then turns and mills features into the front face of the camshaft. Next, the sub-spindle pulls the bar out for grooving… …and lobe milling on a 10-inch section.
Are camshafts in every car?
Every roadgoing production car engine has at least one, and many current engines have two or more. To open and close the valves, a camshaft has egg-shaped lobes — or cams — mounted on a shaft.
Do rotaries have camshafts?
The rotor and housing of a rotary engine from a Mazda RX-7: These parts replace the pistons, cylinders, valves, connecting rods and camshafts found in piston engines. Like a piston engine, the rotary engine uses the pressure created when a combination of air and fuel is burned.
How can you tell if a camshaft has been advanced?
There is a very easy way to tell if the camshaft has been advanced by the cam company when the cam was machined. Look at the cam timing card and compare the lobe separation angle (LSA) with the intake centerline number. If the numbers are the same, then the camshaft has not been advanced. Let’s look at an example.
Which is an example of variable cam timing?
As an example, Fords Variable Cam Timing (VCT) engines only change one lobe while the Ti-VCT (Twin Independent Variable Cam Timing) moves both cams. This is probably more than you wanted to know about camshaft positioning, but this might come in useful at some point.
Why does a DOHC engine use a separate camshaft?
Since a DOHC engine uses a separate intake and exhaust camshaft, this allows engineers to move the intake and exhaust lobes separately. So now with hydraulic adjusters, the ECU can move either cam separately to advance or retard the intake or exhaust.
Is the intake centerline listed on the cam card?
The intake centerline is listed on the cam card at 108 degrees and the LSA is also 108 degrees. In this case, the cam has been ground with no advance as the numbers are the same. Now let’s evaluate a much milder Comp hydraulic roller camshaft for an LS engine.
What do you need to know about a camshaft?
Intake Centerline The cam’s centerline specification is used to determine the position of the lobes on both the cam and as installed in the engine. Most cam companies include an intake centerline number, which is the position of the intake lobe centerline (in crankshaft degrees) relative to top dead center on piston number one.
When does the exhaust open on a camshaft?
Exhaust opening (EO) happens before bottom-dead center (BBDC) and exhaust closing (EC) after top-dead center (ATDC). These points can be checked by degreeing the cam in the engine by degreeing or simply referencing from the information on the cam card supplied with each new camshaft.
What is the intake centerline number on a camshaft?
Most cam companies include an intake centerline number, which is the position of the intake lobe centerline (in crankshaft degrees) relative to top dead center on piston number one. This can be altered by degreeing the cam after it’s been installed in the engine.
How is the lobe separation angle of a camshaft determined?
This value is expressed in camshaft degrees, not crankshaft degrees. This is an important dimension because it establishes the amount of overlap between the intake and exhaust. Lobe separation angle (unlike the intake centerline), can only be determined when the cam is ground.