Tominator

I am curios how having 1.6 roller tip rockers has changed my duraration and lift.

I have a 222@50 with .470 lift cam and best I can figure from reading different articles is with the 1.6 rockers my cam is more like 230@50 with .500 lift

Do these numbers seem right? :confused:

gkull

All the books indicate @ 2 degrees more at the .050. They have proved it with a dial indicator and a crank degree wheel. It's not that much of a change Less than 1% The lift is where the gains generally come from. Because the valve is flowing more CFM by being higher off the seat during it's whole lift cycle.


[Modified by gkull, 12:32 PM 12/11/2002]

yellow 72

Multiply rocker ratio X lobe lift to get lift at valve. Duration change is minimal :cheers:

.470 with 1.5 = .502 with 1.6. Duration not enough to worry about.


[Modified by yellow 72, 2:35 PM 12/11/2002]


[Modified by yellow 72, 2:36 PM 12/11/2002]

Tominator

GKULL; so for duration I would be around 224 if I'm understanding you right

yellow 72; just curious how you come up with the .470 with 1.5 = .502, I tried multiplying and dividing but my answers look weird.


[Modified by Tominator, 8:15 PM 12/11/2002]

mp77

I think he means 1.5 is the stock rocker and your cam is.470 lift. Increasing the rocker to 1.6 equals more lift giving you .502 lift with the same cam.

Smokehouse69

I don't know if this answers your question or not or if it is even right, but it was posted by Aaron74 a few months back. A while back I posted basically the same question and a formula was posted that I seem to remember being similar if not the same. I can't find the posts in searching recent or archived topics.

In the case of my ZZ4 cam, with a dual pattern it looks like the cam with 1.6 ratio rockers, would have

.474/1.52=.312*1.60=.499 and .510/1.52=.336 * 1.60=.537
so .474/.510 with 1.52 rockers would be .510/.537 with 1.60

Your cam with .470 lift (single pattern?) would be as follows.
.470/1.52=.309*1.6=.495

On the duration increase I remember reading an article in a car mag a while back that had the formulas in it too, they seemed to back up what gkull stated that actual duration would only increase a very small amount.

Tominator

So the cam is 222@50 and .470 lift (single pattern) with 1.5 rockers and with 1.6 it increases to 224@50 and .495. This is the info I was looking for.

Guys thank for all your effort. :cheers:


[Modified by Tominator, 12:35 PM 12/12/2002]