When do intake and exhaust cam profiles are the same?
When the camshaft is single pattern (intake and exhaust cam profiles are the same) and the opening and closing sides of the lobes are the same shape (symmetrical) it is a simple procedure to check the phasing of the camshaft for split overlap or an advanced or retarded position.
When does a cam line up with the crankshaft?
When a cam is installed “straight-up,” the imaginary centerlines of the two shafts line up exactly. Advancing or retarding the cam pushes the centerline of the camshaft to one side or the other of the crankshaft centerline.
How to find the intake lobe centerline in a camshaft?
To find the intake lobe centerline, divide the intake duration by two and subtract the indicated intake opening point as shown in our example with the Comp XE274 example. Intake Centerline = (duration ÷ 2) – IO Intake Centerline = (274 ÷ 2) – 31 = 106 degrees Sometimes you find a very mild or stock cam where the IO occurs after TDC (ATDC).
Where are the camshafts located in an engine?
Camshafts are made from cast iron or steel and can be mostly found in the head of an engine, nestled above the cylinders. They are generally found in two orientations: Running along the shaft are lobes which are manufactured to sit at different angles.
Where is the intake center line on a camshaft?
The intake center line occurs 108 degrees After TDC while the exhaust center line is positioned at 116 degrees Before TDC. The intake center line is often used as a primary point for degreeing the camshaft. Another important camshaft spec is something called the Lobe Separation Angle (LSA).
When the camshaft is single pattern (intake and exhaust cam profiles are the same) and the opening and closing sides of the lobes are the same shape (symmetrical) it is a simple procedure to check the phasing of the camshaft for split overlap or an advanced or retarded position.
How is the camshaft connected to the crankshaft?
The camshaft is connected via the timing chain and sprockets at a 1:2 ratio to the crankshaft and therefore revolves once for every two turns of the crank. Its purpose is to operate the intake and exhaust valves in the correct timing with the piston as it sequences thru the four strokes.
When does the exhaust valve open on a cam?
Since the camshaft turns at half of the speed of the crank, the power stroke only sees one fourth of a turn of the cam, or 90 camshaft degrees. As we move closer to the bottom of the cylinder, a little before the piston reaches the bottom, the exhaust valve begins to open.
How are the gears on a camshaft driven?
T he cam is driven by timing gears,chains,or belts lo- cated at the front of the engine. The gear or sprocket on the camshaft has twice as many teeth,or notches,as the one on the crankshaft.This results in two crankshaft rev- olutions for each revolution of the camshaft.
How many Rev-olutions does a camshaft have?
The gear or sprocket on the camshaft has twice as many teeth,or notches,as the one on the crankshaft.This results in two crankshaft rev- olutions for each revolution of the camshaft. The camshaft turns at one-half the crankshaft speed in all four- stroke-cycle engines. CAMSHAFT FUNCTION
How does the shape of the camshaft affect the valves?
The lobes on the camshaft open the valves against the force of the valve springs.The camshaft lobe changes rotary motion (camshaft) to linear motion (valves). Cam lobe shape has more control over engine per- formance characteristics than does any other single engine part.
What’s the proper way to install a camshaft?
Assemble the timing chain and cam sprocket while aligning the timing marks properly, and torque the cam sprocket bolt or bolts to the proper specifications. Next, lubricate and install the lifters, always using a new set of lifters, for proper tappet-to-cam-lobe contact (Fig. 2).
What should I do if I cannot find the timing marks on my camshaft?
If you cannot find the timing marks, DO NOT remove the camshaft – consult a motor manual. After removing the timing chain and lifters, place the cam sprocket back on the camshaft and revolve the cam in the block by hand and observe how freely it turns. Your racing cam should also turn this freely in the block, when installed correctly.
What happens when a cam is installed straight up?
When a cam is installed “straight-up,” the imaginary centerlines of the two shafts line up exactly. Advancing or retarding the cam pushes the centerline of the camshaft to one side or the other of the crankshaft centerline. This changes the Timing of the valve opening and closing events, in relation to the position of the piston in the cylinder.