Thread: Help with the math please!!!

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In order to determine theoretical valve lift, the rocker ratio is multiplied by the cam lift. For instance, if the cam lift is 0.290", then the theoretical lift is 0.290" times 1.5 or 0.435. If the same lobe is multiplied times 1.6, then the theoretical valve lift would be 0.464".

In order to find the 0.290" intake lift at the cam, I simply divided 0.435 by 1.5, so to find the exhaust lift at the cam, you'd divide 0.460" by 1.5 and find that the exhaust lobe lift at the cam is 0.3066". Then to determine the theoretical valve lift after installing 1.6 rockers on the exhaust side, multiply 0.3066 times 1.6 and you get 0.490".

I've changed to 1.6 rockers in engines in the past, but could not tell you definitively that there was a horsepower increase from the increased lift because I never dyno'd the motors before and after. I can tell you that you will experience a difference you can feel with a change from stamped rockers to full roller rockers. In some cases, they have been determined to free-up 20 to 30 hp by those with access to a dyno.

In other words, I felt a difference in the seat of my pants, I'm just not sure if it was the increased lift or the decreased friction or a little of both.

If you do change to 1.6 rockers, check valve to piston clearance, retainer to seal clearance, coil bind and bind at the rocker/stud interface if using stamped 1.6 rockers.