How is intake duration determined in a camshaft?
The first two events determine the intake duration (closing minus opening), which is built into the camshaft. The exhaust opening and closing are the next most important parameters. The exhaust lobe is fixed relative to the intake lobe by the lobe separation angle.
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 happens when one lobe of the camshaft wears out?
All cams wear eventually, and most never notice it aside from the fact that the engine doesn’t feel quite as perky as it used to. But when a single lobe wears out before the rest because of bad oil, excessive spring pressure or bad valvetrain parts, you could easily end up with a bucking, popping, backfiring mess of an engine.
What’s the length of a camshaft on a Chevy?
As an example, Howards Cams’ small-block hydraulic flat-tappet Max Torque camshaft (PN 112021) Chevy measures 222/232-degree duration on the intake and exhaust, respectively at 0.050-inch lobe lift, whereas the advertised duration is 288/302 degrees. Generally, added duration is helpful in high-rpm engines, but not typically in low-rpm engines.
How much valve lift does a cam Hughes Engine have?
Using a 1.5:1 rocker ratio this equals .075″ valve lift. Any duration less than this has no effect on power. Understanding the duration at 0.050″ may seem confusing but the important thing that must be remembered is: as the duration at 0.050″ gets larger the camshaft gets larger and vise versa.
How is the size of the camshaft determined?
When selecting any camshaft for your engine/chassis combination, the size must be determined by the duration at .050″ tappet (lifter) rise. Using a 1.5:1 rocker ratio this equals .075″ valve lift. Any duration less than this has no effect on power.
What are the problems with a cam lobe?
A theory prevails in which a cam lobe that opens to maximum lift and closes instantaneously is quintessential for maximum power and torque operation. Two problems exist with this premise. First, it’s highly impractical due to current technology.
What happens if you change camshaft lobe angle?
Valve lift will bear weight in any decision regarding LSA. “If you changed the lobe separation of a street engine from 112 degrees to 106 and didn’t do anything else,” adds Kaase. “The engine would idle a lot rougher and generate worse exhaust emissions largely because of unburned fuel.”