Engine Performance
Work Example 19

WorkKey Level: 4
NATEF Automotive Tasks:

Problem:

A technician has installed a stock cam in an engine with a lobe lift of 0.375 in. He wants to get more performance from it so he decides to replace his stock 1.5 ratio rockers with 1.6 ratio rockers. How much more valve lift will he get from this modification?

Solution:

Valve lift = (cam lobe lift)(rocker ratio)
With a stock rocker he would obtain a valve lift of 0.5625" (0.375 × 1.5). If he puts in 1.6 ration rockers he would obtain a valve lift of 0.6000" (0.375 × 1.6). If we subtract the two numbers we get 0.0375" increase of valve lift.