Any Difference Between 1.6 & 1.7 RR?

'88Cobra

Member

Oct 21, 2004

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Oct 16, 2005

#1

• Oct 16, 2005

• #1

I have 1.7 ratio roller rockers on my car and while reading many other people's mods have noticed that most of them used 1.6 ratio roller rockers. The parts store gave me the 1.7's without asking me and I didn't know that I had more than one option. Is this a bad thing? Does it matter? Should I switch them? Thanks for any advice!

 

KamiKaziDK

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May 16, 2005

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Mesa, Az

Oct 16, 2005

#2

• Oct 16, 2005

• #2

Instead of having a 498 lift on that E cam, you have around a 529 lift on it now....technically

 

'88Cobra

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Oct 21, 2004

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Oct 16, 2005

#3

• Oct 16, 2005

• #3

KamiKaziDK said:

Instead of having a 498 lift on that E cam, you have around a 529 lift on it now....technically

Click to expand...

So does that mean its almost like I bought a bigger cam, like the FFRP X cam (similar lift)? Is that a good/bad thing?

 

KamiKaziDK

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May 16, 2005

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Mesa, Az

Oct 16, 2005

#4

• Oct 16, 2005

• #4

Sort of, but the Cam is doing the same lift, the lifters are compensating the extra lift for the rockers.....someone correct me if I'm wrong, it's been a while. And you're not getting any more duration.

 

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

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Miami, Ok

Oct 16, 2005

#5

• Oct 16, 2005

• #5

*i deleted this becuase it will confuse people*

 

DMAN302

My mom says thanks for the pearl necklace.

Nov 8, 2003

2,120

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windsor, Canada

Oct 16, 2005

#6

• Oct 16, 2005

• #6

What in the name of #@# are you talking about??

 

KamiKaziDK

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Oct 16, 2005

#7

• Oct 16, 2005

• #7

Yeah, that just confused me.......

 

F

FourG63 97GST

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Aug 13, 2005

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West Palm Beach, FL

Oct 16, 2005

#8

• Oct 16, 2005

• #8

Foxfan88 said:

1.6 and 1.7 refers to the ratio on the rocker arm

the e cam has .498 lift. now with 1.6s
its take the .498 lift the cam gives alone mulitplies it by 1.6 which puts it around .515 or something

the 1.7s will lift it more to the above stated .529

Click to expand...

I dont get this math, is that the formula?

 

PrimerdFury

New Member

Feb 26, 2003

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Fountain Hills, Arizona

Oct 16, 2005

#9

• Oct 16, 2005

• #9

the total lift of the e-cam is already figured using a 1.6 rocker ratio...so lift at the lobe is actually only .311
To come up with a total lift of 1.6 x .311 = .498
If you are using 1.7s you calculate 1.7 x .311 = .529
In this case I would say more lift = good.

 

KamiKaziDK

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May 16, 2005

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Mesa, Az

Oct 16, 2005

#10

• Oct 16, 2005

• #10

Yeah, don't listen to foxfans cracked out math. For all of you thinking....how do they figure that crap out...easy...find out what rocker ratio is used with the cam profile..... 1.6s make .498 lift with the E cam.....divide .498 by 1.6 and you get .311....then multiply it by the 1.7 rockers you're putting on....and you get .529 something

 

95COBRA241

New Member

Sep 3, 2005

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Delray Beach, FL

Oct 16, 2005

#11

• Oct 16, 2005

• #11

Like KamiKaziDK said the larger ratio rocker arms give the same cam greater lift but no added duration. Is it bad, no, if it was you'd know by now. The added lift could haved caused a problem with piston to valve (PTV) clearance. It obviously didn't. Another problem with more lift is the potential for valve float. This occurs when the lift is greater than the valve spring can handle. For example some heads have standard springs which can handle a max lift of .540. Upgrade spring kits allow more than that e.g. .600. At this point you'd already know if there was a PTV issue. Check for the max lift of the springs and upgrade if needed. You don't want to drop a valve in the motor.

 

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

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Miami, Ok

Oct 16, 2005

#12

• Oct 16, 2005

• #12

ok i see now, i didnt understand how it worked so my first post is messed up... i erased to prevent further confusion

i didnt know that the cams were listed with 1.6 rockers, i learn something everyday

 

stang8urimport

Autozone Junkie

Founding Member

Jun 21, 2002

1,499

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59

Daytona Beach, FL

Oct 16, 2005

#13

• Oct 16, 2005

• #13

Max lift doesn't really play a big part in p to v clearance. Duration does. MAX lift happens when the piston is all the way down in the cylinder. The duration (aka the length of time the valve is open) causes the p/v problems.