L98Terror

I just had my springs checked and the were at 115 lbs @ 1.750 should be 145lbs


What problems would that cause?

Recommendations on new springs? .483 & 1.6 RR Intake .520 & 1.5 RR Exhaust

Corvette_Z51

115@installed height is plenty for a L98. A 6500RPM motor might need 145lbs, but not an L98.
Exactly what cam are you running?
I found the Crane stock diameter H11 tool steel springs work well. 120Lbs@installed height and take up to 0.600" lift.


[Modified by Corvette_Z51, 11:45 AM 3/8/2002]

L98Terror

ZZ-9 and it does see 6000-6400 all the time, I've been as high as 7k I think, that's why I took them out and had the measured.

New they were 145 lbs at 1.750

BBA

If you have hy perf lifters, 115 is fine, if you have stock lifters 115 seat will cause the lifters to pump down at rpm.

I think 145 seems too high for a hydraulic roller motor. If you need those kinds of pressure, use the rev kit.

L98Terror

Those were the springs that were recommended for the TPIS zz-9 Cam . I got them form TPIS themselves. Yes they are stock lifters. What does pumping up cause?

JAKE

I had this same back and forth with TPIS over a year ago.

There Insider booklet says one thing about seat pressure for the ZZ9, yet their Tech guys said something entirely different and much higher. If I remember correctly, their booklet says all you need is 90#.

I saw, too, that they specifically say not to exceed 125# on the seat.

What gives with these guys? Booklet says one thing and their Tech support says another. This has come up before, too.

Too little spring pressure will cause loss of valve control and you'll get valve float at high RPMs. The spring will not be able to maintain lifter control as it crosses the nose of the cam and the valves will hit the seats to sharply, causing bounce.

I'm running 125 on the seat and I shift at 5600/5800. Taking a 212 cam any higher is just a waste of time. That why I'm installing a new CompCams Hr next week so I can go higher and still make power - CS 3194-3315 inverted

Just my thoughts; your mileage may differ.

Jake





[Modified by JAKE, 5:25 PM 3/8/2002]

JAKE

If you want to go that high, you need more cam. A ZZ9 is far beyond it's power peak at 6400, not to mention 7000. If you are REALLY up that high, the engine is just revving, but not making any power.

I'll bet if you could see a dyno trace, you'd see your power really fall off once you cross 6, if not before.
Jake

JAKE

Dupe


[Modified by JAKE, 10:09 PM 3/8/2002]

L98Terror

Actually at a 1.800 install your at 125 lbs

Min is 1.250
at 1.800

is max lift of .550

I wonder what my installed height is?

Corvette_Z51

I bought a cool little tool from JEGS to measure installed height. It's a little micrometer you install inplace of the spring.
If you're serious about revving a Superram L98 to 6400RPM all the time then it's wise to measure EACH valve's installed height and shim them to the desired spring height. Leave nothing to chance.
The Lingenfelter Titanium valve spring retainers only cost $95 for our application.


[Modified by Corvette_Z51, 6:56 PM 3/8/2002]

Timmy!

As I found out - too little seat pressure does cause valve float. My engine stops making power at 5,000 rpm due to the wrong valve springs - haven't got it fixed yet :mad :mad but I know LT1's should have peak power at 5800-6200rpm not 5,000.

scorp508

:confused:

My receipt right here from LPE says....

Titanium Valve Spring Retainers

P/N:.............................LN0025-1
Price:..........................$9.37
Quantity:....................16
Total:..........................$149.92

Corvette_Z51

Scorp
The stock valve spring size is 1.250" # LN023 $95.90, you got the bigger 1.437" ones! I went with the crane stock diameter springs made from the nasty H11 tool steel and Lingenfelter Titanium retainers. Not that I need Titanium, but just had to have them! :D


[Modified by Corvette_Z51, 7:25 PM 3/8/2002]

scorp508

Ahhh ok! :D I got those along with new double springs, shims, etc... blah blah all at once.

Corvette_Z51

Boy would I have a field day with your heads! ;)
My buddy & I put the Crane LT1 spring and retainer kit on his '96 LT1 heads with new Manley raceFlo valves. Worked out really well without any porting, just lapped the valves in by hand and cleaned them up. He road races the car and it revs much better now! His rev limiter is set to 6400 and he hits it all the time.



[Modified by Corvette_Z51, 7:56 PM 3/8/2002]

BBA

Not pumping up...pumping down, or, collapsing. It causes a drastic reduction in valve lift and duration at high rpm's, to the point power will fall off prematurely. It's the opposite of valve float, but piston to valve damage will not occur ( but it will beat the heck out of the cam lobe ).

The reason the rev kit works so well is it firmly plants the lifter BODY to the cam...thereby reducing the sprung weight load seen on the valve spring. At rpm levels as high as you are talking ( or any above 5000 RPM ) you will gain quite a bit of power with the rev kit.

Now, the LT4 lifters, or aftermarket high performance replacements, have tighter clearences and are more resistant to hydraulic lifter collapse.