What is it called when both intake and exhaust valves are open?
OVERLAP. As the engine cycles, there is a period when both the intake and exhaust valves are open at the same time. This valve timing is known as “overlap.” Think of this as the exhaust and intake cycles overlapping each other.
Are both valves closed on compression stroke?
It’s up to you. Both valves should be closed if it’s TDC at the end of the compression stroke. If it’s TDC at the end of the exhaust stroke, you should be in the valve overlap zone, with the intake valve partially open and on its way to opening fully, and the exhaust valve partially open on its way to closing.
What are cam lobes?
Cams located on the camshaft that open and close the intake and exhaust valves in time with the motion of the piston. Cam lobes control the valve lift, and there is a direct relationship between the shape of the cam lobes and the way the engine performs in different speed ranges.
What’s the sequence of events in a camshaft?
Looking at a camshaft, the sequence would be as follows: The exhaust lobe pushes open the exhaust valve and the piston comes up to push the exhaust out, then starts to close. The intake starts to open, just as the exhaust is closing, piston goes down, and the intake valve closes.
When is the piston at the top of its compression stroke?
At that point rock back and forth a little till your zeroed in between suck and blow; (it will be real sensitive) and there you have it, top dead center on the compression stroke. Move on to STEP FOUR. Now remove the hose and place a long screwdriver; coat hanger or straw into the spark plug hole to feel the height of the piston.
Where are the timing marks on a Suzuki engine?
Timing. On most Kawasaki and Suzuki engines the marks are lines on the cam sparockets and should be even with the top edge of the cylinder head. There is one extra thing on Kawasakis and Suzukis. Count the number of cam chain rollers from the exhaust timing mark to the intake timing mark.
What happens when you install a larger camshaft?
When a larger duration camshaft is being installed, unless the lobe centerlines have been changed, the overlap will be increased. If installing larger camshafts in a turbo application, advancing the exhaust and retarding the intake will reduce the inherent increase in overlap caused by upgrading to a larger profile.
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.
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).
Looking at a camshaft, the sequence would be as follows: The exhaust lobe pushes open the exhaust valve and the piston comes up to push the exhaust out, then starts to close. The intake starts to open, just as the exhaust is closing, piston goes down, and the intake valve closes.
How are the specs written on a camshaft?
To eliminate confusion, the spec is written as -1 degrees. This makes the math simple as 51 + 180 + (-1) = 230 degrees as listed on the card’s right column under the Duration heading. The column just before Duration on this Summit Racing camshaft card is something called Lobe CL or Lobe Center Line.