Determine how much 1.6 rockers change cam duration
#1
Determine how much 1.6 rockers change cam duration
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:
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:
#2
Team Owner
Re: Determine how much 1.6 rockers change cam duration (Tominator)
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]
[Modified by gkull, 12:32 PM 12/11/2002]
#3
Le Mans Master
Member Since: Apr 2000
Location: cincinnati ohio
Posts: 5,202
Likes: 0
Received 8 Likes
on
7 Posts
St. Jude Donor '09
Re: Determine how much 1.6 rockers change cam duration (Tominator)
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]
.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]
#4
Re: Determine how much 1.6 rockers change cam duration (yellow 72)
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]
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]
#5
Racer
Member Since: Oct 2002
Location: texas city texas
Posts: 393
Likes: 0
Received 0 Likes
on
0 Posts
Re: Determine how much 1.6 rockers change cam duration (Tominator)
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]
[Modified by Tominator, 8:15 PM 12/11/2002]
#6
Le Mans Master
Member Since: Aug 2000
Location: Semper ubi, sub ubi
Posts: 9,662
Likes: 0
Received 6 Likes
on
6 Posts
Cruise-In VI Veteran
Cruise-In VII Veteran
Re: Determine how much 1.6 rockers change cam duration (Tominator)
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.
For example, my lift is .460 (lift with standard 1.52 rockers) / 1.52 = .302 (cam lift) .302 X 1.6 = .484. (your lift with 1.6 rockers)
.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.
#7
Re: Determine how much 1.6 rockers change cam duration (Smokehouse69)
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]
Guys thank for all your effort. :cheers:
[Modified by Tominator, 12:35 PM 12/12/2002]