They won't really change the idle quality, what you hear is duration and overlap, not lift.

 

Silver- Lift moves from the .470 to .501.

 

I think I have this right???

Duration will increase something like 2 to 3 degrees on both opening and closing sides at the valve at advertised and .050" and on up is about all...

And as Nantooch said, the lift goes up to .501 by the equation [(lift x 1.6 ratio)/1.5 ratio].

I guess this is right, isn't it guys??

pdq67

 

Paul, I think the duration increases a bit everywhere except at the IO/IC and EO/IC points, at which the same degrees are read because there is either no lift (and thus no multiplication of it with either ratio rocker) or barely any lift (not readable amount of change?). Least that's how I remember it.

 

From what I have heard, for the average cam going from 1.5 to 1.6 ratio rockers, duration increases about 1-2 degrees, but also the ramp rate (rate of opening & closing the valves) is accelerated. For a car that has heads that can handle the extra flow, power is increased in the mid & upper ranges without sacrificing idle quality, low end torque and drivability since the higher ratio allows the valve to pass more air, not by longer duration (which effects driveability/ power curve), but by opening the valves further. Powerwise, it seems like all gain and little lost, however, there is the increased stress on the valvetrain's springs and lifters, and you must make sure the pushrods are clearanced properly. Magazine tests have shown 0-20 hp increases, with the greater gains probably for a severly under-cammed motor. If you have all the cam your heads can flow, it won't help.

I probably overstated the obvious.

 

Thanks guys!

pdq67

 

thanks for the responses, now i know just how much lift itll make, im thinkin about gettin summit's set of 1.6 full rollers for $159, anyone run these, have good or bad luck with them? -derek