I'm considering the purchase of a new set of roller (or roller tip) rocker arms to use with my new ZZ4 cam (.474/.510 using 1.5rr).

I know if I use 1.52rr, it will change the lift to .480/.517.

If I use 1.6rr, it will change the lift to .506/.544.

What I am wanting is maximum low-end & mid-range torque (and HP if i can get it, but I have more fun with torque )

Can anyone tell me how, if I use a ratio higher than 1.5, my cam/engine would respond? Will my powerband be impacted?

FYI - I plan on using Dart Iron Eagle 180cc, 64cc cylinder heads.

Any info would be greatly appreciated.

Thank you!

 

You will probably pick up 10-15 ft-lbs and hp across the board.

 

That sounds great!

Going to .506/.544 (using 1.6rr) seems like a big jump.
I know the factory cam lift is .415/.430.
Do I need to worry about valve clearance going to a ZZ4 with 1.6rr?

 

I agree. You really only need to install the 1.6 rockers on the intake side.

 

But if i only did the intake side, that would be .506/.510.

Would that mess up my low/mid-range torque goal?