cam/rocker question

[JohnnyC]

So (cam lift) * (rocker ratio) = valve lift. I've read up that everyone advises against using big ratio rockers with an aftermarket cam, reason I'm guessing being the resulted lift is excessive. now if I were to custom grind a cam with a long duration (something like 224deg) and a lift that would result in something like .530 on a 1.8 rocker, would there be any advantage to the longer rocker versus a cam ground for use with a 1.6 rocker?

In other words, the cam ground for the 1.6 rockers has a higher lift, but still results in .530 lift at the valve and the cam ground for the 1.8 rockers still results in .530 lift at the valve also.

I figure there would be less travel for the pushrods and it would result in equal valve lift, less stress on the lifters and maybe higher revs?

Basically, I plan on a bigger cam than what I have now, and with cam comes full valvetrain. Which way sounds like a better game plan?

[AZ3.8Camaro]

Re: cam/rocker question

Less travel from the push rods but they have to push harder.
I would take the lift from the cam over lift from the rockers anyday.

Use the higher lift rockers when you can't get anymore out of the cam.
Make sure your heads have the valve guides cut down if you are going over about .520" lift. Make sure your heads flow well at higher lifts (IE ported...)

[UDLOSE98]

Re: cam/rocker question

I would do 1.7's with a cam because aftermarket 1.7's are lighter than stock 1.6's. Ligther rocker arms will result in less float.

[AZ3.8Camaro]

Re: cam/rocker question

Yeah if you have the money, I can't argue that logic.

But I am a cheapskate...

[UDLOSE98]

Re: cam/rocker question

damn when the **** did you get a viper??????

and i think that right there means you cant possible be cheap.

[AZ3.8Camaro]

Re: cam/rocker question

damn when the **** did you get a viper??????

and i think that right there means you cant possible be cheap.

Correction - That is exactly how I got the viper. NOT blowing my money on questionable mods. :D

With rear tires that cost over $400 a peice I can no longer be cheap!

[UDLOSE98]

Re: cam/rocker question

christ what kind of tires are you buying 19 - 330's?

[AZ3.8Camaro]

Re: cam/rocker question

Haha no, 335/35ZR17s Michelin Pilot Sport PS2s.
The size is specifically for Vipers, so they get the infamous "Viper Tax"

[UDLOSE98]

Re: cam/rocker question

hell yea thats a big tire, mine are over 200 each 18" - 315's

[AZ3.8Camaro]

Re: cam/rocker question

hell yea thats a big tire, mine are over 200 each 18" - 315's

Yeah they acutally hold a lot more power than I thought they would.

Might I recommend the PS2s. Best cornering street tire I have seen. Love them.

[UDLOSE98]

Re: cam/rocker question

they sound awesome, but with a price tag like that.....eh, now im the cheap skate.

[AZ3.8Camaro]

Re: cam/rocker question

Good tires would do so much more for anyone that rockers ever will!

[UDLOSE98]

Re: cam/rocker question

well ya, i agree

[JohnnyC]

Re: cam/rocker question

I would do 1.7's with a cam because aftermarket 1.7's are lighter than stock 1.6's. Ligther rocker arms will result in less float.

Maybe I will go with aftermarket 1.6's unless I can get a custom ground cam to justify the extra rocker ratio. I'd imagine a 1.6:1 can be made to be even lighter than a 1.7, and I'd like to spin the motor to 7k RPMs so I don't want any valve float etc. I'm looking into some strong yet lightweight valves also - I've heard of breakage with the SI valves so I'd like to stay away from them.

[UDLOSE98]

Re: cam/rocker question

wait, you're the same dude thats been talking about a big build FOREVER