I have a 305/5.0L engine out of a 1985 pontiac bonneville and i want to get a new cam for it. How much of a lift can i goto without changing valve springs. I was wanting to get a 465/488 lift cam from summit. Any suggestions......
It is not just the lift that you need to worry about, it is the PRESSURE of the springs. Stock springs are much lighter than performance springs. Bigger cams make less power down low, and more at higher rpm - and at higher rpm, with higher lift, the stock springs will not be able to control the valves.
Find a cam with close to stock lift, but with a little more duration, unless you are willing to do the springs.
'67 Coupe, 455, pump gas, 11.46 @ 115.4, in Feb '05 HPP Shootout article