How does valve size affect performance?

Often tines, large valves will actually decrease air flow. Let’s take a look at the Chevy 305 heads as a good example: The normal valve size in the “performance” 305 head is 1.84″ x 1.50″. Well, the fact is, larger intake valves in a 305 head will hurt overall air flow of the head, especially under .

How do you calculate maximum valve lift?

To figure this out, all you need is the radius of any valve opening in the cylinder head. This is approximate, to get a more exact answer you must have the diameter of the valve stem. Take this lift and divide it by the rocker arm ratio to get the maximum cam lift.

What is maximum intake lift?

The intake centerline is the point of highest lift on the intake lobe. It is expressed in crankshaft degrees after top dead center (ATDC). Likewise the exhaust centerline is the point of highest lift on the exhaust lobe. It is expressed in crankshaft degrees before top dead center (BTDC).

Why a higher valve lift is required?

The higher the lift, the more the engine will breath. This is good if you want more power at higher rpms. This also means your engine takes longer to develop power. Choose a lift that gives you the power you want at the rpm you want.

How do you calculate the maximum valve lift?

Maximum valve lift is calculated by multiplying lobe height at its highest from the base circle of the lobe, times rocker arm ratio. The rocker arm ratio multiplies (increases) the effective lift of the camshaft lobes. For example, a 0.310” lobe lift cam yields 0.496” of valve lift when using a 1.6 ratio rocker arm.

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 big of a lifter do I need for a titanium valve?

It is possible to lift titanium valves to as much as 0.950 while still using a 0.842-inch lifter diameter as well as a stock cam journal diameter and a 3/8-inch pushrod. As convenient as that may seem, it’s on the ragged edge.

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.