IRACE87

How stiff of a spring can I use with my Hydraulic roller lifter set up?
Or I should say who on this site is using really stiff springs with good result on a Hydraulic roller lifter set up?

I used to have valve float at around 6000 rpm with my AFR #8015 springs spec are 1.540 OD 145#@1.820 and 355#@1.250 with steel retainers.

I'am now having valve float at around 5800 rpm with comp cams 987's spec are 1.430 OD 121#@1.800 and 388#@1.200 with titanium retainers.

By the way I have the AFR rev-kit also. And I should make power up to 6500-6600 with my engine.

Thanks

PAT

fastredtruck

What cam are you using?

Are the springs installed at the correct hieghts?

Dyno Don

iTrader: (7)

I don't see how you could have valve float with that setup.
Basic rule of thumb is, stay under 140# on the seat and 390# on the nose with hydraulic lifters.

IRACE87

I have a Lazer cam with 236/240 .544/.537.

Yes

This is what is happening to me. The valve floats and the lifter plunger pumps up and takes up that slack, it will HOLD the valve open as the oil filling the lifter body cannot bleed out of the feed holes fast enough to allow the plunger to go back down to where it won't be holding the valve open anymore. At that point the engine just stay at that rpm as long as I keep it WOT. Used to be 6000-6100 rpm with the AFR spring, I'm now down to 5700-5800 with the 987's from comp cams.

I know Matt87GTA is having the same problem with a different set up.

I'm having that problem with 1/4 of a turn preload on the lifters, if I preload them with only 1/16 of a turn I will then be able to rev higher BUT, the valvetrain will still be unstable and I basicaly won't make any more power above the rpm it used to stop reving with 1/4 of a turn.

So I need to find a spring that will be stable up to 6600-6700 rpm with my set up.

PAT

Matt87GTA

Yeah all indications are that I am having some valve float above about 6500 RPM. The specs on my engine just don't jive with it not making power past that RPM - aside from the hydraulic cam having issues with valve control that is. There is at least one thread where we hashed through this quite a bit....

https://www.thirdgen.org/techbb2/sho...ht=valve+float

Mine has a ZZX cam, Brodix installed springs setup for the cam, and an AFR Hydra-Rev.

I have pretty much decided that when I finally dig into this engine to fix the piston-slap issues (I'll be going .040" over and bumping the compression to at least 11.5:1) that a solid roller will be going in.

FYI, I did re-dyno with the lifter preload backed off, a 4" cold air intake setup, a 58mm TB, and 42lb SVO injectors and hit the numbers in my sig - same dyno. Hard to say what part played what role though...

F-BIRD'88

A hydraulic roller valvetrain is just too heavy.
More spring pressure may not over come the relitively low natural harmonic resonance frequency (valvetrain surge) that you're experiencing. Lighter parts will help a lot.
hollow stem valves, titanium valves, custom made super light weight titanium hyd roller lifters would go a long way.
The typical retrofit hyd roller lifter is just too heavy.

Once you get into the 130+ seat pressure springs , even if the lifter plungers do not collapse, you'll be seeing the increased valvetrain wear life of a solid roller valvetrain becasue of the extreme spring pressure ( pushrod, rocker, etc.) designing a camshaft that makes good torque and throttle responce will allways limit its high speed rev limit without big spring pressure. ( rapid open , rapid close design) A new more gentle cam lobe with high rev closing ramps would help rpm stability, and make more high rpm power. Consult your cam grinder/ engineer. If you don't get good answers, try Crane cams or Isky cams tech dept Althou the guy at Lazer cams seems to know his stuff.

Once you get into that kind of spring pressure you might as well go to a solid roller lifter and cam design for high rpm as you'll be getting the same valvetrain wear life anyways. (Trying to run a hyd setup on the very edge will require just as much or more fuss and adjustment, etc etc. You're just at the limit of a hydraulic rollers setups rpm capability unless you can drasticly reduce valvetrain mass.
$$$(light weight parts)$$$

A proper designed (quiet operation) tight lash Solid "Street Roller" cam and valvetrain would be better for you.
The new internally pressure lubed solid roller lifters should be in your plans for street use (idling) ( Comp EndurEX)
Or at least groove the lifter bores for full time oiling flow.

Crane Cams's "SR" solid "street roller" series cams work nicely. See if the guy @ Lazer Cams Can set you up with something like this.

IRACE87

Thanks for all the input, I will probably try one last set of springs from the guy at Lazer Cam.
He told me that one guy in the Engine Master contest ran 7500 rpm with no exotic parts (even used GM roller lifters).
The spec are 165#@1.800 and 335#@1.200.

That will most likely be my last try to get this set up to work. Next winter I will go solid. Time to put some $$$$$ aside.

Thanks

PAT