Vavletrain's weak links
 

logically, everything should be replaced for high RPM motors... but how much can everything take...

What RPM will each STOCK part break:
What RPM will each STOCK part will cause valve float:
Whats the biggest cam before each STOCK part will break:
Whats the biggest cam before each STOCK part will cause valve float:
- Hydrolic Lifters
- Pushrods
- Rocker Arms
- Springs
- Retainers
- Locks
- Valves

Bumppp

If a cam goes in there Replace.....

Pushrods w/ Properly measured Chromoly
Springs

You can reuse the retainers if you stick with Beehive springs, go to Ti if using a Dual coil spring.

Lifters when you kill them, alot of that has to do with spring pressure.

Stock rockers last a long while, only on high rpm set ups do I see people opt for Jesel.

Valves and locks should not need replacing.

It really depends on what your goal is.

so with say PRC .660 springs, which have and open pressure of 390lbs would need new lifters due to the extra force required to open the springs?

so is it better to get springs rated for .600 for a .595 lift cam, or would prc .660 be the best

Stock valvetrain components are for the stock valvetrain (exception is the rockers). If you are going to run a bigger spring with more RPM then you need better lifters among other things.

^naturally.. i want to know the RPM that everything is safe for/ rated for

If you are putting in such a stout spring, I am assuming that you are going to install a HUGE cam. In that case you need:
TI retainers w/ compatible locks and seats for the springs
Chromemoly pr's
That is the only absolute requirements.

Now for the optional, recommended replacements
LS7 lifters
LS2 timing set
ported oil pump

Optional performance repalcements
Yella Terra rockers

ok... but do you need such a stout spring for say a .595 lift cam? would it have an advantage? higher RPM without valve float? last longer?.. compared to say a spring rated for .600 lift

If you already have the PRC dual springs rated to .660" lift, I don't see any problems running it. It will be more stable being a stiffer spring, but I don't think it would be required over a quality spring rated to .600" lift.
What cam are you thinking about running?

If he's running a .595 cam, then a .600 is not enough spring as it's too close for comfort in case of an over-rev.

ya that what i figured... im kinda looking at PRC 2.5 5.3s an they come with .660 springs.. and im looking to go with roughly a 228 .590 cam but figured id see if its worth replacing anything now while i try and save up funds

Those heads are a good choice. Great heads for the price. Have you looked at the 228R cam?

yeah but 918s are rated at .625 and PAC has a beehive rated at .650.

its all cost/ HP ratio... yes ive looked at 228R, VRX3/4, some TR stuff......

But those are the advertised specs on the spring. You wont know exactly what the spring can take untill you get the springs you plan to use and have them measure to see where they coil bind. Also there is deflection in the valvetrain, not to mention its a hydraulic set up.

If a spring is advertised for 0.600" lift, then there is sufficient clearance to actual coil bind. In the case of PAC-1218, it is advertised for 0.600" lift to a second height of 1.200". Max coil bind is rated at 1.140" but actual coil bind is around 1.100". When you start pushing the limits you must get more accurate coil bind readings to ensure proper setup.

Anybody who changes out springs should use an installed height micrometer to verify the setup. I suppose if you do a true drop in (stock everything on the valve side; valves, locks, retainers, seats) then you can probably get away with not checking them if you know the factory specs.

If you want to learn more, please take the time to read this: CransCams on Valve Springs

Ken