Valve lift question

Marcohotrod said
well I was giving an example of engines that came stock with 1.5 rockers. and my point is that whatever engine you have, an extra .020" lift is not likely to give much more power if you have the right cam for the combo to begin with

A higher rocker ratio is not a crutch for a poor cam selection. It can make a good cam better or a bad cam worse. And, the additional lift has very little to do with it. Interestingly though, there are a lot of people who get twisted out of shape if they are missing .010" lift at the valve, but the geometry can be a wreck and that's acceptable. But, you are right that the .020" extra lift won't make much of a difference in power. On a really good head, there probably wouldn't be more than 5-7 cfm difference at full lift.

The benefit is the extra area under the curve, much like the advantage of a roller cam. The valve opens quicker, and dwells longer, allowing the engine to breathe better without increasing the seat timing and negatively affecting lower RPM power. Bigger cam power with smaller cam driveability. Btw, correcting geometry does the same thing, so just bolting on a higher ratio roller rocker without getting the geometry right can hurt power. Did you adjust the shaft height when changing rockers?

If you aren't making more power with a 1.6 rocker over a 1.5, then the cam is probably too big already, or you don't have a stable valvetrain to take advantage of the increased rpm potential. I rarely use a 1.5 ratio anymore, and always recommend a 1.6 or higher on a small block.