Rocker Geometry

[Wbulk]

The results of the test are in the table below. Notice under B, C, and E these were all tested with the stock pushrod in stock form. From these the old style cast stock rocker was best with an actual ratio of 1.51 followed by the Comp Cams Magnum with 1.468 and then the stamped steel pedestal rocker at only 1.45 ratio.

Under D and F columns these results were by using the mid-lift net method and the mid-lift gross method, measuring the correct pushrod length and adjusting the adjustable pushrod to that length, running it through the test sequence and recording the lift measurements. It was amazing to me how both these lifts came up considerably over the whole 260 degree lift range over the stock figures. Also interesting was the old stock cast steel rocker came out the best with a total lift of .509 and an actual ratio of 1.59. This was attained by using the net mid-lift method. I used net method on the stock cast steel rocker (D column) because with the gross method the rocker retainer was hitting the top of the retainer.

I think the lesson learned through this testing process was a demonstrated need to measure your rockers to determine how close the ratios are compared to what they are supposed to be, and that the mid-lift method does work for raising the lift over the entire range.

Now consider if you changed heads, have roller rockers and new roller lifters how far things could really be off. If I was buying an expensive engine I would want to know the actual test in the table on what I was getting.

Added: The results would be far better represented in a line graph but this is the best I could do. If anyone knows how to do graphs really well that would be great if this data could be converted over.