I currently have a large solid roller cam in my 358. I am running Crane Radi-Arc Full roller 1.5 arms now. Would it be a wise to go to a 1.6 set-up??? What would be the gains here? the car currently runs great, but it's time for a little more power.

 

Usually the higher ratio rockers are good for 5-20hp, but not always. So, it's just a guess at this point. Do you have cam specs and head flow numbers? That would allow a more educated guess, along with any other setup info. Of course, changing to 1.6:1 rockers may require new springs and you will have to verify adequate piston to valve clearance.

Rich

 

The cam itself doesn't care what the rocker ratio is. As mentioned above, the valve train needs to be checked for the increased lift.

The valve springs must not bind at full lift. The piston to valve clearance should be checked. The bottom of the spring retainer must not hit the top of the valve guide/seal with the increased lift.

Lets say your cam has .600" lift with 1.5 rockers, the cam lobe will have a lift of .400" Swapping in 1.6 rockers will now give .640" lift. That extra .040" lift can cause problems to the valve train if clearances are not checked.

Swapping to a higher rocker ratio is a poor man's cam swap but sometimes it's an easier way to change the cam profile without doing a swap. You can get the increased valve lift if the cam grind can't provide it because of the lobe design. The drawbacks is that most people don't realize that other factors are involved in the rocker swap. Do a swap and complain about poor performance not realizing that the valve springs are now binding etc. If everything checks out then go ahead with the rocker swap. I'd guess an increase more in the 5-10 hp range though.

 

Ok, here's the specs. Doug Herbert Solid Roller cam .574 lift- 255dur. @.050" Running E-TEC 200 Heads. Speed-Pro Forged Pistons 5.7 rods. I thinks the car runs great as it sits, so I may-not change it, but was just wondering. Thanks.