Bouncing the valves?

[hogracer3d]

looking for any suggestions/ past experience about this
We've been chasing an issue for a while now with loosing valve lash ( this time after only 3 laps).
I't happened on us with 2 different pairs of heads (RHS RR23, and Dart Iron Eagles), 2 different blocks (Dart and OEM 010) , 2 different cams (comp and now Jones both solid about .620 lift) Ti and or stainless, used 11/32 stems, 7mm stems. 5/16 stems, .600 long on the RR 23's to .100 long on the Darts, Valve brands have been Ferrea, Si, and Manley, all the same result, it beats the keeper groves up till it slips up the stem.
Different springs, keepers and retainers
Jesel shaft rockers, Jesel belt drive
good fuel, and only 32-33 degrees timing.
no tulip on the valves, it just beats up the valve grind angles till they ride a little deeper in the seat

completely frustrated

[hogracer3d]

[hogracer3d]

[hogracer3d]

notice how much difference in how much of the valve tip sticks out of the keepers.
prior to running it for 3 laps, the valve tips were all consistent and up about .200 above the keepers.
now some are nearly flush with the keepers (1st pic) and several of the others are all over the place in how much they stick out

[hogracer3d]

spring pressure is 130# on the seat, and 440# over the top

[powerslide]

I showed one of our valves to a machine shop that it looked like the lock was starting to pull and he said that some keepers have a chamfer and some are square at the top. Take one of the springs off and show us the valve and keepers.

[hogracer3d]

oh it did chew up the keeper groove on several.
the 2nd time we sent the valves back to Ferrea and they replaced several and touched up the others.
that was with the RHS raised runnner heads, this time its the same short block, but with Iron Eagle heads.
The machine shop set up the Jesel shaft rockers, and it only needed 1 .030 shim under the stand.
they are the square cut keeper grooves, which some folk dont like, but the machinist says thats not a legitimate argument, because they still use them on blown alcohol drag hemi's without issue.

[powerslide]

I think the trouble comes if you use the chamfer keepers on the straight valves I might have that backwards.... Did they use the mid lift method to determine the shims or do you know how they came up with it?

[perfconn]

It doesn't matter what its on or who put it together,if your floating the valves,its going to beat everything up.You can be floating the valves a lot earlier than what you think if you have really radical lobes.

[billetbirdcage]

what's the install hieght on the springs and the coil bind hieght and the actual lift at the valve?

What I'm getting at is, you are probably experiencing spring surge. You likely have way too much clearance from coil bind at the lift your running which is causing spring surge which is likely the source of the valve train unstability and most likely harsh valve bounce. This would explain the beat up seats and lock to valve groove issues.

[hogracer3d]

^^^ tell me more ! ^^^^ interesting, never heard of that.
I'll have to see what the installed height is from the machine shop, but I do remember him telling me that there was "plenty" of room before coil bind.
Should we run it at a minimum ? What is the minimum?
Solid flat tappet with 7800 chip rule

[hsdiefusion16]

We typically try to keep guys on our springs between .060 and .100 from bind. depending on the application that changes slightly but for endurance applications like yours if you are too far from bind you definitely will have spring surge. You don't have enough seat pressure for your application, if it were me I'd have 150-160 on the seat. Whats your installed height and how much lash are you running?

[TBRE]

I agree with what's been said so far, but even in valve float, or spring surge, your locks should NEVER climb up the valve stem, only way that can happen is if they are wrong for the valve or retainer. TB

[hogracer3d]

I was incorrect on the spring pressures after I talked to him yesterday.
They are close to 150# on the seat, and 420# over the top.
But Mike Jones of Jones Cams suggested 160# on the seat, and to use 2 dial indicators and check lift at the lifter and retainer through the range of motion to see if the rocker ratio stays true the entire range

[hogracer3d]

Hot lash is .018, but Mike also said we could tighten up hot lash .002 to .004 and see if that helps the condition