1.5 vs 1.6 Rocker Ratio? Hows this work?

[blownarrow]

I read some here on the site what the ratio difference between the two are.
But now I can seem to fined the thread. I also don't have or know the formula for figuring this out, I know one of you guys knows this so I'm taping into the collective wealth of knowledge..
I'm just trying to figure out what lift change will be when running a cam.
If I have a .440 lift with 1.5's what will the change be for a 1.6? this is just an example not what I have...

thanks

[sanjay]

.440/1.5 = .293
Current Max Valve Lift/Current Rocker Ratio = Current Max Cam Lift

.293 X 1.6 = .469
Current Max Cam Lift X New Rocker Ratio = New Max Valve Lift

Unless there are other factors that I'm not considering, mathematically this should be right.

[geoffinbc]

Yup thats right. Divide by the old ratio to get the lobe lift and then multiply by the new ratio to get the new valve lift.

[blownarrow]

.440/1.5 = .293
Current Max Valve Lift/Current Rocker Ratio = Current Max Cam Lift

.293 X 1.6 = .469
Current Max Cam Lift X New Rocker Ratio = New Max Valve Lift

Unless there are other factors that I'm not considering, mathematically this should be right.

? so a cam with 7/16" lift using an 1.5 rocker only opens the valve 19/64" thats smaller? I thought anything over 1. incressed the lift?
Am i reading into this wrong?
Wouldn't the larger 1.6 rocker also change lobe center and duration?

please help soo confused........

[sanjay]

? so a cam with 7/16" lift using an 1.5 rocker only opens the valve 19/64" thats smaller? I thought anything over 1. incressed the lift?
Am i reading into this wrong?
Wouldn't the larger 1.6 rocker also change lobe center and duration?

please help soo confused........

I understood that .440 was you current VALVE lift not your CAM lift.

@.440 CAM lift
Valve lift at 1.5 is 0.660
Valve lift at 1.6 is 0.704

If you already have the CAM lift all you have to do is multiply it by the rocker ratio to get your VALVE lift.

[blownarrow]

I understood that .440 was you current VALVE lift not your CAM lift.

@.440 CAM lift
Valve lift at 1.5 is 0.660
Valve lift at 1.6 is 0.704

If you already have the CAM lift all you have to do is multiply it by the rocker ratio to get your VALVE lift.

Sorry, if i didn't ask this question right.. thank you I under stand that math..
so if I have Example stock cam of
Stock 18-20 196 202 282 290 .395 .410 109 109
.395 x 1.5 = .592 and .410 x 1.5 = .615
but
.395 x 1.6 = .632 and .410 x 1.6 = .656

is this right?

[sanjay]

Yes it is..

[blownarrow]

Cool ok....
So going back to the other question, Wouldn't the larger 1.6 rocker also change lobe center and duration?

-Also what's too much lift for our stock Valves?
-And why does some cams on the market for These motors require solid lifters vs. hyd?
For example Crane cam 250801 F-28-3067 has a lift of .460 and .480 and needs solids but the crane cam 253941 h-272-2 has .454 and .480 but need hyd?

isn't learning fun!

[bszopi]

I think you need to just read an article on camshafts and go from there.

http://60degreev6.com/content/Gen_3_Camshafts?

The lobe centerline and duration are a function of the camshaft itself, and has nothing to do with the rocker arm. So therefore, neither is affected when changing rocker ratio.

[blownarrow]

The lobe centerline and duration are a function of the camshaft itself, and has nothing to do with the rocker arm. So therefore, neither is affected when changing rocker ratio.

so the ratio change doesn't make it open sooner and close later, but
it would make the valve move faster.. in order to have the same duration but have a higher lift means the valve must move faster to cover more space in the same amount of time?

[SappySE107]

yes.

[blownarrow]

Anybody running 1.6:1's on a hi lift cam?
Looking at a .3100 - .3280 lobe that will put me in the .5008 - .5248 with the 1.6:1

[1986]

bout much HP is this 50 dollar mod good for?