Photograph of the failed rocker arm shaft. One of the major causes of component failure is faulty manufacturing. This includes all effects that increase brittleness or those inducing cracks and or stress raisers in the component.
Anyway, do rocker arms add horsepower?
For engine applications that demand a step up, replacing the stock stamped or cast steel rockers with aluminum roller rockers will typically produce a gain of 10 to 15 hp with the same lift ratio, and even more of a power gain with a higher lift ratio.
However, how do I choose my rocker arm ratio? The ratio of a rocker arm is determined by the distance between the centerline of the pivot point to the centerline of the roller tip (or area of contact with the valve stem), divided by the centerline of the pushrod to the centerline of the pivot point (X).
On another note, how do I know if my push rods are too short?
If the witness mark is too close to the intake side of the valve-stem tip, the pushrod is too short. If the witness mark is in the middle or toward the exhaust side of the valve-stem tip, then the pushrod is too long.
What is the purpose of rocker arm?
A rocker arm (in the context of an internal combustion engine of automotive, marine, motorcycle and reciprocating aviation types) is an oscillating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it.
BESTSELLER NO. 1 in 2021
Ford Racing M6529A302 Rocker Arm Shim Kit
Use with bolt-on roller rocker arms
Package Dimensions: 20.7 H x 5.1 L x 6.2 W (centimetres)
1.5 rockers lift the valve 1.5 times the lobe lift of the cam, 1.6 lift the valve 1.6 times lobe lift. Generally, 1.6 rockers are used to improve the lift of a camshaft that has low lift. They can also be used to get the valve lift into a specific head flow range.
According to This Article from Hot Rod magazine, a . 1 increase in rocker arm ratio (such as 1.6 to 1.7) will increase lift by about . 030, which would put me right back at the . 542 lift of the X-303, while maintaining the extra duration of the F-303.
With broken or loose rocker arms, the exhaust valves and intake valves can't function correctly and the cylinder associated with the faulty rocker arm will be disabled. This will ultimately limit the performance of your engine and your ability to drive the car smoothly and safely.
Single Overhead Cam The cam actuates rocker arms that press down on the valves, opening them. ... These springs have to be very strong because at high engine speeds, the valves are pushed down very quickly, and it is the springs that keep the valves in contact with the rocker arms.