ROCKER ARM RATIOS:

Fig. 3.10.19

Stock rocker arm ratio for the small block Chevrolet is 1.5:1.

 When the ratio between the push rod end (A) and the valve end (B) of the rocker arm is increased, the valve lift (X) will increase using the same lift camshaft (Y).

 

As an example:

  If you were using a cam which had a lobe lift of .320 using a 1.5:1 ratio rocker arm you would have a valve lift of .480-inch, and if you change the rocker arms to a 1.6:1 ratio that would give a new valve lift of .512-inch. This is most helpful on the Exhaust valves.

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