H/C lifter and spring replacement
03-26-2013, 11:52 AM
#1
TECH Fanatic
Thread Starter
H/C lifter and spring replacement So I know when you do a H/C package you need to replace springs and lifters and seeing another lifter thread got me thinking about frequency of replacement of these parts. For more aggressive cams people say you need to replace valvetrain more frequently because it is rougher on the components, which is understandable. I don't know if lobes are the only thing that controls that or if lift has anything to do with it so I'm curious about that. Like say for example you have LS7 lifters and .650" springs. I'd like to know, comparatively to each other, what the following cam setups would mean as far as how often you need to replace things, a simple ordering would be good.
A) Higher lift cam (relative to the .650" springs, something like .620"/.630") with aggressive lobes such as XE-R
B) Lower lift cam (relative to the .650" springs, something like .595"/.598") with aggressive lobes such as XE-R
C) Higher lift cam (relative to the .650" springs, something like .620"/.630") with less aggressive lobes
C) Lower lift cam (relative to the .650" springs, something like .595"/.598") with less aggressive lobes
Whenever I get around to doing a H/C swap I don't want to have to replace springs and/or lifters every 10,000-15,000 miles. I've seen some people need to do that IIRC.
A) Higher lift cam (relative to the .650" springs, something like .620"/.630") with aggressive lobes such as XE-R
B) Lower lift cam (relative to the .650" springs, something like .595"/.598") with aggressive lobes such as XE-R
C) Higher lift cam (relative to the .650" springs, something like .620"/.630") with less aggressive lobes
C) Lower lift cam (relative to the .650" springs, something like .595"/.598") with less aggressive lobes
Whenever I get around to doing a H/C swap I don't want to have to replace springs and/or lifters every 10,000-15,000 miles. I've seen some people need to do that IIRC.
03-26-2013, 04:40 PM
#3
I posted this the other day. I think this should help you understand. But basically, go with as stiff a pushrod as you can fit, use quality lifters, lightweight valves, adequate springs, and cam lobes that don't brutalize your valvetrain. If you have an unstable valvetrain, you're losing power. And a super crazy aggressive lobe at the same duration of some of the nicer more modern endurance lobes is usually less than a 5-7HP difference.
What you need to make sure is good is your valvetrain and stable under load at 6k+ RPM. If you float the valve or loft the lifter because of too much cam lift, too much ramp speed, and too little spring pressure, the system will be out of control. Sometimes this appears as valve float on a dyno. Other times it doesn't. It appears as lowering power and failed lifters/bent pushrods/broken rockers. All of that means the valve is hung open too long and contact can occur.
Do you know why I'm going to run mine tighter? Valve control. It starts with EPS endurance lobes ground on a billet Cam Motion core. Morel 5206 lifters ride the lobes and Manton 11/32nd .120" wall pushrods connect the lifter to the stock GM rocker arm. Stiffness and control on the cam side of the valvetrain. On the valve side, I went light weight. The stock rocker is the lightest of all rockers and it rides on upgraded trunions. The entire valvetrain is controlled by PAC 1904 springs with TFS Ti retainers, for low weight. The final piece of the puzzle is lightweight, hollow-stem, turned-down LS3 valves.
Do you know why I'm going to run mine tighter? Valve control. It starts with EPS endurance lobes ground on a billet Cam Motion core. Morel 5206 lifters ride the lobes and Manton 11/32nd .120" wall pushrods connect the lifter to the stock GM rocker arm. Stiffness and control on the cam side of the valvetrain. On the valve side, I went light weight. The stock rocker is the lightest of all rockers and it rides on upgraded trunions. The entire valvetrain is controlled by PAC 1904 springs with TFS Ti retainers, for low weight. The final piece of the puzzle is lightweight, hollow-stem, turned-down LS3 valves.
03-26-2013, 04:47 PM
#4
Oh, one other thing too. The LS7 lifter would be fine if you had super light weight valves, slow ramp cam, and low pressure springs. That's what it was designed for. The farther away you get from those specs, the more you're operating your lifters under conditions they were not designed for, which is why I think we see a lot of the failures with the LS7s.
