Which ratio rocker?

[Hemet8]

As i understand it, with any given cam, there is specs for standard ratio rockers that the car has on it. So if you were to go from a 1.6 to a 1.7, that is in effect like going to a bigger cam??? My '95 i think has stamped at 1.5. In '96 i think they went to full roller at 1.6?? Where can i find a set of bolt on 1.7's for a 3400? (stock heads) Maybe a 2001 model year (no emmisions holes in the heads) Thanks for the help, as i really don't know squat about this.

[bszopi]

RE: Which ratio rocker?

Your 95 has 1.6s and that's all that's available that'll fit a 3x00 head currently.

[geoffinbc]

Agreed I have not seen any 1.7 rockers. Keep in mind though you can use a smallblock narrow body rocker. So look around and see if you can find 1.7 ratio.

I have seen 1.65 ratio.

[torq455]

350 chevy center bolt rockers will work. i've seen some at 1.7 but not full roller

[Syn]

i asked this question and people ask me why,

but i don't know if your staying with your stock cam or what you never said, also whats done to the motor?. adding higher lift rockers is just like adding more lift to the cam. 1.6 is good i was going to add 1.7 to my 272 cam but i think i'll stay with 1.6.

try it out and see how it works

[geoffinbc]

Exactly. It also adds more effective duration to the valve aswell. Increased ratio rockers are a good performance boost. Made a difference on my 3.4L. It made a big difference on my buddies 4.3L with a Crane 260/276 cam in it

[torq455]

oh yeah, on my stock 3.1 i just added 1.6 roller tips and an UD pulley, TB bypass, little too agressive chip, K&N air filter, no converter and 180 stat.

[torq455]

on the 272 cam, if you have the 3400 heads, you will gain a little more with 1.7's on the intake, not much at all on the exhaust. maybe 1-2 CFM. check out the flow charts Ben has. i was really shocked at the intake.

[Syn]

on the 272 cam, if you have the 3400 heads, you will gain a little more with 1.7's on the intake, not much at all on the exhaust. maybe 1-2 CFM. check out the flow charts Ben has. i was really shocked at the intake.

how much would the lift go up adding 1.7 ratio rockers? i was never sure on how to do a conversion or if there was a chart.

and you ever run your car with the mods you got?

[v6h.o.]

example:

.427 inch VALVE lift with 1.5:1 ratio rockers.

.427/1.5 = .2846 CAM lobe lift

take cam lobe lift and X by new ratio

example .2846 x 1.6 = .455 inch lift at Valve.

[Syn]

example:

.427 inch VALVE lift with 1.5:1 ratio rockers.

.427/1.5 = .2846 CAM lobe lift

take cam lobe lift and X by new ratio

example .2846 x 1.6 = .455 inch lift at Valve.

you the man thanks

[Hemet8]

Wow, thanks for all the help. So, how do i shoe horn on 1.7 roller rockers and where do i get them from?

[torq455]

on the 272 cam, if you have the 3400 heads, you will gain a little more with 1.7's on the intake, not much at all on the exhaust. maybe 1-2 CFM. check out the flow charts Ben has. i was really shocked at the intake.

how much would the lift go up adding 1.7 ratio rockers? i was never sure on how to do a conversion or if there was a chart.

and you ever run your car with the mods you got?

just in case you didn't do the conversion by now. lift with 1.6 is .484/.512. with 1.7 is .514/.544. as you can see from the flow chart, you'd gain about 5-6 CFM intake, and maybe 2 CFM on the exhaust. I wouldn't put the strain on the valve train for the exhaust gain you won't feel. BTW, these are stock 3400 heads I am refering to.

[torq455]

oh, and no, i haven't gotten quarter mile times. with an almost flat road, meaning slight incline, and easing on the throttle to prevent wheel spin, i stop watched my own 0-60 of 8.6 and 8.7. it's an improvement over my other 0-60 of 9.0 and 9.1. my mileage hasn't changed a bit!

[Syn]

on the 272 cam, if you have the 3400 heads, you will gain a little more with 1.7's on the intake, not much at all on the exhaust. maybe 1-2 CFM. check out the flow charts Ben has. i was really shocked at the intake.

how much would the lift go up adding 1.7 ratio rockers? i was never sure on how to do a conversion or if there was a chart.

and you ever run your car with the mods you got?

just in case you didn't do the conversion by now. lift with 1.6 is .484/.512. with 1.7 is .514/.544. as you can see from the flow chart, you'd gain about 5-6 CFM intake, and maybe 2 CFM on the exhaust. I wouldn't put the strain on the valve train for the exhaust gain you won't feel. BTW, these are stock 3400 heads I am refering to.

well are you talking about being n/a how about my case with boost and ported heads. if your doing a cam and lifters ,you have to upgrade the valve springs anyways for the new cam and might as well do pushrods also, so 1.7 i don't think would be that much more of strain if everythign is properly upgraded