1.72 Roller Rocker Questions

83GTMUSTANG · 06-01-2005, 07:24 PM

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...........

06-01-2005, 07:28 PM

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.

83GTMUSTANG · 06-01-2005, 07:37 PM

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

06-01-2005, 08:04 PM

Quote:

Originally Posted by 83GTMUSTANG

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

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.

NOTCH306 · 06-01-2005, 08:09 PM

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

Rev · 06-01-2005, 08:41 PM

Notch is exactly right.

Rev

tmoss · 06-03-2005, 07:38 AM

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.

NOTCH306 · 06-03-2005, 10:40 AM

it opens the same time it will just have more lift

tmoss · 06-03-2005, 12:03 PM

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.

HotRoddin · 06-04-2005, 12:35 AM

Quote:

Originally Posted by tmoss

At the cam face it lifts the same - NOT at the valve tip

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.

06-01-2005, 07:24 PM	#1
83GTMUSTANG N-V-ME Join Date: May 2005 Location: SOUTHFIELD,MICHIGAN Posts: 155	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........... __________________ 88' LX MUSTANG: LINCOLN ROTORS , AIR SUSPENSION FRONT AND REAR, SUBFRAMES, ROLL CAGE, 92' BLOCK, MSD 6AL, ACCEL 8.8 WIRES, ACCEL COIL, EDELBROCK F4B INTAKE (PORTED),2 IN. 4 HOLE SPACERS, HOLLEY 600 CARB.,HOLLEY BLUE FUEL PUMP AN REGULATOR, E 303 (.498 IN. 220 DUR.) CAM, (.535 IN. OF LIFT W/ 1.72 SCORPIN ROLLER ROCKERS), PORTED E7'S, FLOWTECH 1 5/8 LONG TUBE HEADERS, 2 1/2 IN. H PIPE, 2 CHAMBER FLOWMASTERS WITH 3 IN.DUMPS, T-5, 3.73 GEARS, 5 LUG AEROSTAR AXELS, 245-45-17 96' COBRA WHEELS

06-01-2005, 07:28 PM	#2
Simi Stang Guest Posts: n/a	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.

06-01-2005, 07:37 PM	#3
83GTMUSTANG N-V-ME Join Date: May 2005 Location: SOUTHFIELD,MICHIGAN Posts: 155	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 __________________ 88' LX MUSTANG: LINCOLN ROTORS , AIR SUSPENSION FRONT AND REAR, SUBFRAMES, ROLL CAGE, 92' BLOCK, MSD 6AL, ACCEL 8.8 WIRES, ACCEL COIL, EDELBROCK F4B INTAKE (PORTED),2 IN. 4 HOLE SPACERS, HOLLEY 600 CARB.,HOLLEY BLUE FUEL PUMP AN REGULATOR, E 303 (.498 IN. 220 DUR.) CAM, (.535 IN. OF LIFT W/ 1.72 SCORPIN ROLLER ROCKERS), PORTED E7'S, FLOWTECH 1 5/8 LONG TUBE HEADERS, 2 1/2 IN. H PIPE, 2 CHAMBER FLOWMASTERS WITH 3 IN.DUMPS, T-5, 3.73 GEARS, 5 LUG AEROSTAR AXELS, 245-45-17 96' COBRA WHEELS

06-01-2005, 08:09 PM	#5
NOTCH306 Registered Member Join Date: May 2005 Location: York, PA Posts: 46	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. __________________ 1990 Notch, 306, T-56 trans, 3:73 gears, zex 100 shot, gt-40,z-303 cam, roush 200 heads, powerdyne on the way

06-01-2005, 08:41 PM	#6
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	Re: 1.72 Roller Rocker Questions Notch is exactly right. Rev __________________ '66 Coupe, 306, 350-375 HP, C-4, 13.07 e.t., 104.8 mph, 1/4 mi. O.B.C. #2 '66 coupe

06-03-2005, 07:38 AM	#7
tmoss Registered Member Join Date: Mar 2003 Location: Saint Louis, MO Posts: 634	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. __________________ Tom (Torque) Moss 88Gt 5spd Vert, FLowmaster Catbacks, stock cam advanced 4° @ 108.5° ICL, NMRA prepped GT40P heads 1.85/1.55 valves and 1.7 rockers, MAC P headers Jet-Hot coated, 97 Exlporer intake (ported lower), TB and injectors. 277RWHP/330RWTQ (SAE). http://www.fastlanecars.com/

06-03-2005, 10:40 AM	#8
NOTCH306 Registered Member Join Date: May 2005 Location: York, PA Posts: 46	Re: 1.72 Roller Rocker Questions it opens the same time it will just have more lift __________________ 1990 Notch, 306, T-56 trans, 3:73 gears, zex 100 shot, gt-40,z-303 cam, roush 200 heads, powerdyne on the way

06-03-2005, 12:03 PM	#9
tmoss Registered Member Join Date: Mar 2003 Location: Saint Louis, MO Posts: 634	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. __________________ Tom (Torque) Moss 88Gt 5spd Vert, FLowmaster Catbacks, stock cam advanced 4° @ 108.5° ICL, NMRA prepped GT40P heads 1.85/1.55 valves and 1.7 rockers, MAC P headers Jet-Hot coated, 97 Exlporer intake (ported lower), TB and injectors. 277RWHP/330RWTQ (SAE). http://www.fastlanecars.com/

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