1.7's or 1.6's

Cwalk

New Member

Sep 25, 2006

78

0

0

Virginia Beach, Va

Oct 23, 2006

#1

• Oct 23, 2006

• #1

Most of the people here have 1.6:1 roller rockers. Why not 1.7:1's or 1.72:1's? I see people often using Cobra heads but not using the same size rocker as a Cobra? In the Cobra it proved the combination does make a few more horses and increase the air flow into the intake. So if you are using a more free flowing intake? Why not a bigger rocker?

 

MAC'n89Blckstng

Active Member

Jun 11, 2003

1,012

3

36

NJ

Oct 23, 2006

#2

• Oct 23, 2006

• #2

1.7's may be too much lift for many applications. I have an E303 cam with 1.7's and I'm actually losing power from having them. I have too much lift for my heads. 1.6's are the stock ratio. People usually get them for the valvetrain durability.

 

bubba-dough

Active Member

Dec 28, 2004

1,044

2

38

Indiana

Oct 23, 2006

#3

• Oct 23, 2006

• #3

Its all aboout the cam being used. Also piston to valve clearance.

 

BlownFiveLiter

have car, will race....wait, it doesn't run

15 Year Member

Nov 29, 1999

3,133

18

108

Chicagoland

Oct 23, 2006

#4

• Oct 23, 2006

• #4

Figure the lift at the valve on a Cobra is .479 I/E with the factory 1.7 roller rockers, but only around .450 if you were to use a 1.6 rocker. Now figure you were to take say... an E cam and run it with 1.7 rockers like MAC'nBlckstng is doing. The E cam is rated at .498 lift I/E with 1.6 rockers, but when you use 1.7s, your lift increases to .529. Some heads may benefit from the increased lift, but you may run into PTV clearance issues or hurt flow velocity with that much lift. You need to take all aspects of a cam into account, including lift, duration, and lobe separation if you want to have the best cam suited to your particular application.

 

25thmustang

Mustang Master

Sep 5, 2003

2,021

85

99

Montgomery, NY

Oct 23, 2006

#5

• Oct 23, 2006

• #5

I have 1.7s, but also have a stock cam. Another thing you can play with is shimming them, and to get the ultimate combination some people stagger them intake to exhaust. You run whats best on your combo!

 

Strype

Cuthbert catcher

Founding Member

May 11, 1999

61

34

104

Huntsvegas, AL

Oct 23, 2006

#6

• Oct 23, 2006

• #6

1.7's require the pistons to be notched unless used on a stock cam...

 

Cwalk

New Member

Sep 25, 2006

78

0

0

Virginia Beach, Va

Oct 23, 2006

#7

• Oct 23, 2006

• #7

25thmustang said:

I have 1.7s, but also have a stock cam. Another thing you can play with is shimming them, and to get the ultimate combination some people stagger them intake to exhaust. You run whats best on your combo!

Click to expand...

The heads Im getting are 210's from D&D motorsports. I have a Trick Flow stage II cam. The heads are supposedly good for .652 of lift. The cam says it has .542/.563 with 1.6 rockers. So I think I should be able to make good power with my 347. Im shooting for 450hp NA.