Originally Posted by bluecamaroz28

Here is some additional information on valve springs for hydraulic roller engines (obtained from a cam grinder, not a sponser here or I will mention the name):

Hydraulic roller cams present a unique problem for higher rpm use, especially above 6000-6500. The heavy lifters and relatively fast acting profiles (which is what makes real power) require lots of spring pressure to get that heavy tappet back on the base circle of the lobe and hold the valve closed. However, virtually all springs you can find from other sources that do have enough seat pressure, also give very high open pressures. This sucks, since open pressures over 340-350 will squeeze the oil out of the lifter, and making the profile "look" smaller to the engine. (If you have difficulty with this one, contact the actual lifter manufacturers). It's as if a slice of the backside of the lobe was removed, as far as the breathing part of the engine is concerned. Therefore, the rpm ability given by the higher seat pressure is taken away by the heavy open pressure reducing the duration seen by the engine. Without that duration, the engine will not rev as well or make as much high end power.

Originally Posted by bg-sdpc

NEW GM Performance Parts Hydraulic Roller Lifter for LS-Engines
#SD8689 $217.85/set

You heard it first from SDPC! This new lifter will work in all LS- engine applications and is specifically suited for race cams and high RPM applications. They can also be used as an upgrade for stock lifters and are suitable for street applications. These lifters were developed for the CTSV Cadillac Race Team that used the “short stroke” LS7 style engines that raced in the Grand Am Cup Series during 2005. If you recall these engines were built using the LS7 block, LS7heads, and LS7 intake but the sanctioning body required the teams to meet the 5.7-liter engine size of 346ci. There were several different combinations tried but most of these engines used a stroke of approximately 3.200”. The demand to make race winning horsepower with a short stroke guarantees the unavoidable element of high RPM’s.
Initial testing, before these new lifters were developed, showed a definite valvetrain stability problem above 7000-rpm’s. Several remedies were tried, but in the end it was determined that the lifter had the biggest contribution to the RPM limit. This new lifter has internal changes made to the hydraulic components which resulted in a significant RPM increase. After installing the new lifters, these engines were now making power at 8000-rpm and they regularly saw 8500-rpm’s without any problems! WOW! The CTSV dominated the first races, not only did the sanctioning body enforce an RPM limit on the short stoke Caddies but they eventually implemented more restrictions to limit the horsepower on these LS7 equipped 346ci engines.
As a reminder, hydraulic roller cam valvetrain stability is a function of many different variables; camshaft design (ramp acceleration), pushrods, valve springs, rocker ratios, spring pressures, valve weight, the weight of all valvetrain components, oil pressure, RPM, etc. It is imperative that you have sufficient spring pressures, quality push rods and lifters, proper lash adjustment, and the lightest valvetrain components you can afford to maintain accurate stability at high RPM’s. Match your components to meet your RPM range!
We recommend a preload setting of 0.060” (cold) with these lifters, in most cases with adjustable rockers this is usually somewhere between 1-full turn and 1-1/2 from the “Zero-Lash” point. This is the same preload as a stock lifter!

Stock lifter on the left in both pictures.

Originally Posted by N4cer

So do you guys think it's a good idea to move to these lifters if running LSK lobes then?

Originally Posted by N4cer

80k miles... what 'cha think?