just wondering.... if i was to change the rockers in my 305 from the stock stamped stell to let's say roller 1.6 ratio's. whould i see a decent performance increase? using the stock cam, the larger ratio would make the cam "bigger" correct? The main fear i would have is with the larger ratio would that push the valves father? meaning would i risk having the pistions hitting the valves at all? i would much rather just change the rockers then the cam at this time mostly due to the fact i dont have the time or money to do a cam swap. and dont feel like digging into everything. I heard a rocker swap is not all that complictated...maybe it is, but im sure a shop would take less money for that. just trying to get some more power out of my 305 for a while. any input is a big help.
~Opha~

 

Opha,

You've done some homework, I see.

Yes, there would be a performance increase, but only a slight one. The larger ratio would indeed make the valves open farther. If you do the math, you'll also discover that the effective duration would increase slightly as well. Most of the gains in your case would be from the slightly increased lifts, and probably more from the reduced friction afforded by roller fulcrums and tips.

And it's good that you're thinking about the clearance issue, but with a stock cam and heads, there is little chance of piston/valve interference.

You're also correct that changing rockers is not very complicated, just time consuming. Plan to take extra time to inspect the valve springs, push rods, and set the valve lash/lifter preload. The rest is fairly straightforwards disassembly and assembly.