What does the duration of a camshaft mean?
What does the duration of a camshaft mean?
DURATION: Duration is how long the cam holds the valves open. It’s expressed in degrees of crankshaft rotation (remember, the cam rotates at half the speed of the crank). A 280-degree-duration cam holds the valves open longer than a 260-degree-duration cam.
How is camshaft duration measured?
Camshaft Duration is the measurement of the time one valve begins to open until it finishes closing. Duration is measured in degrees of crankshaft rotation, not camshaft rotation. 050 inches, the duration is measured from that point. Intake Duration at .
How does Cam duration affect idle?
Again, keeping all else constant, more duration will make the engine less efficient at low rpm, with more overlap dilution of the induction charge, and the later intake valve closing reducing the trapping efficiency. Therefore, a long-duration cam will cause rough running at idle (lope) and a loss of low-rpm torque.
What is the point of Degreeing a camshaft?
The purpose of checking or degreeing-in the camshaft in the engine block is to determine whether or not the camshaft is installed in the correct relationship or phasing with the crankshaft. However, the most important step in phasing a camshaft is finding absolute T.D.C. of the #1 cylinder piston.
What is a three quarter cam?
The original 3/4 race cams are the forerunners of today’s street-performance grinds. The term likely originated in the ’50s as the burgeoning hot-rod industry was modifying Ford Flatheads to drag race on airport runways and attempt top-speed runs on dry lake beds.
What causes a lopey idle?
A rough idling engine can be caused by spark plugs or spark plug wires. Spark plugs use the electrical current received from ignition coils to ignite the air/fuel mixture within the combustion chamber. A plug that is damaged or installed incorrectly can result in fuel being burned at an inconsistent rate.
How does Cam duration affect torque?
Duration has a marked affect on the cams power band and drivability. Higher durations increase the top-end at the expense of the low end. As a general rule, cams with 220-235 degrees of duration tend to produce good low end torque.
Is Degreeing a cam worth it?
Pit Stop with Marlan Davis: Degreeing a custom cam ensures its maximum performance, helps prevent piston-to-valve contact, and protects against assembly error. The bigger the cam, the more important this is.
