Engine runs great and makes normal sound all the way up to 6K RPM. Then the normal sounds goes up 2X the volume like a switch was thrown. Sounds like valvetrain to me and just makes a louder clackity clackity clack. Drop under 6K and its gone.

Is this the sound of valve float or something else.

 

You shouldn't be having valve float.

-Rick

 

http://camaroz28.com/forums/showthread.php?t=592005

Well he does.

 

My power falls like a rock at 6K RPM even before the HP peaks. The engine sounds rough above 6K RPM. I have a fast ramp high lift (just above .600" each). Sounds like float.

 

In that other post you said the springs were installed a little tall right??

There is room then for a little shimming??

A pack of shims and a couple hours work might be worth a shot, though IMO if a shim fixes it now it will not be a long term fix, will be a temporary patch that will cheaply confirm the issue. Think if it is on the ragged edge with the shims barely allowing control they will fatgue and float again soon. Like I said though a cheap thing to try.

 

My PAC 1218's were alittle on the soft side. I have installed PSI LS1511ML's which are a good bit stronger. Should have enough spring now. The rockers are ticking louder as a result of the stronger springs too. Install height is 1.765".

Rough sound above 6K remains.
WTF

 

what roller rockers are you using..i know my cranes are loud as **** at idle..but under acceleration you cant hear them cause of the gmmg

 

Running Comp Pro Mag 1.6 ratio roller rockers. Thinking about dropping to 1.5 ratio rockers to drop the gross lift to a more reasonable high ~.560" GL.

 

http://www.pacracing.com/Beehive_Spr...Set_of_16.html
LS1511ML Beehive OD1.290" ID.630" 120lbs@1.800 360lbs@1.175 rate/384 max lift .625" bind 1.100"

Less on the seat more over the nose.
You know valve float can also happen by the valve bouncing off the seat not just tossing the lifter off the nose of the cam.

It still could be float.

 

Wow, less on the seat! With aggressive ramps, less seat pressure will make valve bounce more of a possibility! When that valve closes, you want it to STAY closed.