How is valve lift measured?

How is valve lift measured?

How is it measured? Valve Lift is the amount (usually in inches) that the valve is lifted off of its seat. It is usually measured with a dial indicator at the tip of the valve. Lobe Lift is the amount (usually in inches) that the cam lobe increases in radius above the cam base circle.

What is used for measuring valve lift?

In order to measure the valve lift and velocity, typically a Laser Doppler Vibrometer (LDV) is used.

What is valve lift and duration?

Duration is how long the valve is off its seat. It is listed in degrees of crankshaft rotation. When someone refers to a “big cam,” they mean it has longer duration, not higher Lift. Advertised Duration is the degrees of crankshaft rotation that the lifter is raised more than a predetermined amount.

What is maximum valve lift?

The valve lift is the distance by which the valve is raised from its seated position when it is fully opened. These valve springs will allow a maximum safe valve lift of 9.9mm only. The camshaft controls the speed of valve opening, valve lift off the valve seat, and how long the valve stays open.

What does more valve lift do?

Increasing valve lift allows more open space in the intake and exhaust ports of the cylinder. Theoretically, this means more air and fuel can be drawn in. More exhaust gases can be pushed out.

How can I tell what cam is in my engine?

Locate the ID number on the camshaft. It is typically located in the center of the cam between the lobes. The ID number will consist of either eight or nine digits; the last four numbers identify the cam and its specific application. Match the number to a Chevrolet camshaft part number listing.

How is Max valve lift measured?

Starting from the lobe on the camshaft, to get maximum valve lift we multiply the peak lobe lift by the rocker ratio. So 0.360-inch lobe lift multiplied by the 1.7:1 rocker ratio equals 0.612-inch of valve lift.

How do you check a valve lift with hydraulic lifters?

The MOST accurate way is to pull the intake and check lifter rise off the edge of the lifter. If you trust the rocker ratio, multiply the lifter rise by that ratio. If the engine has Rhodes type lifters in it, they will bleed down like that with low (no) oil pressure.

What makes more power duration or lift?

Lift is the amount a cam lobe actually moves a valve off its seat and is measured in fractions of an inch. Duration is the amount of time a cam keeps a valve off of its seat, measured in degrees of crank rotation. The more valve area open to flow, the more power an engine can theoretically make.

Can you have too much valve lift?

If you put too much pressure on the valve train by using an agressive lift, the studs can pull out of the heads.

How to calculate the valve lift of a camshaft?

Valve Lift = 0.270 x 1.6 = 0.432 in. Example #2: A camshaft with 0.468 in. of valve lift with a 1.5 rocker ratio has 0.312 in. of lobe lift. Lobe Lift = 0.468 / 1.5 = 0.312 in. When calculating valve lift for a cam with Solid Lifters, it is important to account for Valve Lash.

How do you check valve to piston clearance?

A quick and dirty method for checking valve to piston clearance is to attach a Trock fixture or similar to the cylinder head, and with the engine positioned at TDC, open each valve until contact just occurs, measure how much lift it took, and subtract the TDC lift figure.

What is the ratio of valve lift to lobe lift?

Valve Lift = Lobe Lift x Rocker Arm Ratio Lobe Lift = Valve Lift / Rocker Arm Ratio Example #1: A camshaft with 0.270 in. of lobe lift will have 0.432 in. of valve lift with a 1.6 rocker ratio. Valve Lift = 0.270 x 1.6 = 0.432 in.

How does lobe lift work on a camshaft?

Lobe Lift = Valve Lift / Rocker Arm Ratio Example #1: A camshaft with 0.270 in. of lobe lift will have 0.432 in. of valve lift with a 1.6 rocker ratio. Valve Lift = 0.270 x 1.6 = 0.432 in. Example #2: A camshaft with 0.468 in. of valve lift with a 1.5 rocker ratio has 0.312 in. of lobe lift.