1.72 Roller Rocker Questions
 

I Hear Different Storys And Read Different Stuff On These,,,,,but Do They Give More Duration An If So How Much I No It Gives More Lift Whats The Difference From 1.7's An 1.72's How Much More Lift...........

Re: 1.72 Roller Rocker Questions
 

Not sure how much additional lift the bigger ratio roller rockers give you exactly...but I think my B-303 cam has something like a .494 lift. The 1.72 rollers I installed brought it up to a .512 lift I believe. As far as I know, the bigger rockers will not increase your duration...just the lift. As for what's the difference between 1.7 & 1.72 rockers...I would say next to nothing. The difference would be very minimal being that they are only .02 inches longer. I guess the 1.72 rockers might give you 1-3 thousandths more lift, lol. The increase in lift #s that I listed may be a little off...but I'm sure someone else will chime in with better specifics.

Re: 1.72 Roller Rocker Questions
 

A B Cam Has .480 In. Lift W/ 1.6's .510 W/ 1.7's 1.7's Give You .30 In. Lift Extra To Your Cam But What About 1.72's

Re: 1.72 Roller Rocker Questions
 

Ok, that makes more sense. Because I thought that my pedestal mount 1.72 rockers I had on my stock motor brought the stock lift of .444 up to something like .477. You're talking about a few thousandths more with 1.72 vs. 1.70s. It's hardly worth figuring it out. I don't know the exact formula but I'd imagine the 1.72s raise the lift something like .32-.34. I'd go for the 1.72s.

Re: 1.72 Roller Rocker Questions
 

to get value life you multiply cam lobe lift by rocker ratio. it does not affect duration at all.

Re: 1.72 Roller Rocker Questions
 

Notch is exactly right.

Rev

Re: 1.72 Roller Rocker Questions
 

The 1.7 lifters give more VALVE duration, not cam duration. The valves open earlier and faster giving more area under the curve for airflow.

Re: 1.72 Roller Rocker Questions
 

it opens the same time it will just have more lift

Re: 1.72 Roller Rocker Questions
 

At the cam face it lifts the same - NOT at the valve tip which is where the air enters. This debate occured on Corral too, and Buddy Rawls mocked up both with a dial indictor and degree wheel on an engine that he uses to check his cams and proved that the duration at the valve is longer. I forget how many degrees were added, but if your after every last deatail to make power - this is one that works.

Re: 1.72 Roller Rocker Questions
 

agree with tmoss, more effective duration at the valve. Valve clears the seat at the same degree point, but reaches its max lift sooner, giving you more effective duration.