Bouncing the valves?

[billetbirdcage]

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

I gotta agree with tony, while it may be hard on the grooves and locks typically the valve will give up before the lock groove. By the part number on the retainers it appears to be a Crower 10 degree tool steel retainer, are you sure you have 10 degree locks and not super 7's or regular 7 degree locks? There is also conventional (square groove) and bead loc (round groove) so they have to have the matching locks to the valves.

The groove is more a location devise more then anything, the major holding of the valve is really supposed to be done by the collet effect of the angle interference fit of the retainer and lock, it's pinching the lock on the valve holding it.

I'm far from a professions engine builder, but I'd say you have at least 2 things going on. Wrong retainer/lock combo for the valves and most likely either spring surge from too much distance from coil bind or another valve train issue that is cause it to be extremely unstable.

Here is an old quote from Billy Godbold an engineer at comp cams on coil bind:

Godbold notes that "from high-speed video and testing, it is clear that adjacent coils contact as you approach the valvetrain limiting speed. Hence, modern springs are designed to run near coil bind and use the coil-to-coil interaction for improved damping at or near max lift. This interaction is one of the most effective means of dampening spring surge, but the valvespring must be properly designed in terms of solid stress to safely use this interaction." Depending on the intended use, the spring and cam-lobe design, and the engine builder's preferences, you will now see coil bind safety margins vary from as low as 0.015 inch to as high as 0.120 inch, with tighter numbers predominating on very stiff valvetrains. In a serious valvetrain, anything more than 0.150 inch can cause spring surge, which can greatly reduce the available spring load needed to close the valve.

locks/retainers:

The retainer must also be compatible with the valve lock angle. For years, valve locks were machined at a 7-degree angle of incidence. Comp Cams developed (and patented) 10-degree locks, which have a larger contact area that spreads the load over a greater surface area. For most performance work, the 10-degree configuration has pretty much become the industry standard.

But there are still some 7-degree proponents. SAM's Massingill maintains that the 7-degree lock puts greater clamping force on the valve. "The step on the inside of the retainer only locates the retainer to set the correct installed height; it doesn't actually hold the retainer in place. This is done by the clamping force of the spring pressure; as pressure increases, so does the clamping force." The so-called Super 7 lock (which is actually 8 degrees) may be the best of both worlds: Available from Manley and others, it has almost as much surface area as a 10 but the clamping force of a 7.

While the lock's outer angle must mate with the retainer, its inside shape must match the valve stem diameter and be compatible with the shape of the valve stem's retention groove. Different valve stem sizes will require corresponding locks. As for shape, traditionally, most U.S. domestic valves were machined with square keeper grooves. Motorcycles, imports, many late-model domestics, and now high-end custom valves often use a superior radiused beadlock groove. Less likely to propagate stress cracks, the radiused groove has no sharp edges and a greater contact depth-but the machining process is more costly. Consider beadlock retention mandatory for small-diameter valve stems (less than 5/16 inch) or with any titanium valves; it's also a good idea with larger-stem stainless valves or more-than-200-pound seat pressures if you need to order custom valves anyway.

[billetbirdcage]

^^^ 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

You will have to check out the specs on install hieght for your heads but a comp 977-16 will generally put you around 150 seat and 440 open and have the right distance before coil bind on about a .600 lift cam, but it's been years since I used a flat tappet so who knows if the spring is the same as it was years ago. Least with the 977 10 years ago, set up that way with about .050 from bind they would run at 8300 RPM or more for 3 seasons and not lose pressure, we just replaced them cause they were old but never showed any signs of pressure loss and never broke one. Between the guys I knew running that spring combo, there was probably 50 or more engines that saw the same thing on spring life and never a failure.

But you know how things change, parts are not the same as they used to be so it's possible the source for the springs or the specs have changed. Do your own research before taking advise from someone you don't know (ME, LOL).

Search spring surge on youtube or google and you will find some video's of it showing what it does. If the machine shop your using doesn't know about this and the effects of being too far from coil bind: FIND ANOTHER MACHINE SHOP OR ENGINE BUILDER!

TBRE (Tony is pretty sharp) and plenty of others could likely fix your issue pretty quick.

[hogracer3d]

I am actually a customer of Tony's but this stuff isn't his.
My machinist is the same one we've used for years, and way too smart of a guy to mismatch stuff.
Very thorough and meticulous .
just came back from there, and we've now seen some signs of detonation in a couple of cylinders, with 2 intake valves tuliped and .030 longer than they used to be, and 2-.018 longer
verified timing mark to be correct, checking fuel quality and delivery now

Springs are Comp 977-16 installed at 1.850

[billetbirdcage]

looking at the first picture you posted:

#7 exhaust the top of lock to valve tip appears to be around .100 or so
#7 intake appears to be .050 or so

See if all the intakes and exhaust are the same, or it's random between all the valves

Just from that a couple of obvervations.

1. Either it has 2 different locks on it, like a +.050 install hieght lock on one and a STD on the other
2. Maybe it has same height locks but since the thing has been beating up the seats so the valve seat depth is way off to each other and someone to set the stem hieght for the Jesel has to remove a lot of material from the intakes. Like someone didn't set the valve depths on the valve seats and they are all random depths and just ground the stems to get the stem height correct.
3. 2 different valve brands with different dimensions from groove to valve tip
4. Retainers different from one valve to another as the part number shows that to be a +.085 install height retainer. I can't see the exhaust retainers part number but maybe it's a non drop retainer.

I have gotten miss packaged stuff before like a set of 11/32nd locks that had one 3/8 lock in it, it's easy to miss. Also I really don't trust miss matching part brands on locks and retainers, I have often found that the angles don't match sometimes, like retainer being a 10.5 degree and a different brand lock being a 9.5 degree. You can also get one/several +.05 lock/locks in a std set or vice versa. It's easy to miss, I got a set of assembled AFR heads for a customer that had one half a 3/8 lock on one valve so it happens.

I know they changed the install hieght on the 977 from 1.800 to 1.850 years ago, I used them at 1.800 which was 160 on the seat and with a .600 lift cam minus the lash it was around .060 from coil bind. So depending on your actual lift numbers at the valve (remember it won't be exactly what the card says cause you have rocker and push rod flex so it's not uncommon to lose upwards of .04 lift in some cases - doubtful in your case but more like maybe .010) your probably not horrible on the coil bind, but I would check it and see where your at. Also check the actual bind of the springs, not what is listed in the book as it's usually off a fair amount.

Good luck

[hogracer3d]

thanks,
all the valve tips prior to running hot laps were a good bit further out of the keepers, and were all similar looking height wise.
now the #7 intake is not far from flush with the keepers, and the rest are all over the place.

I could see them possibly being different brand stuff, or maybe being misboxed or something.
we've had to get all new intake valves now because the grooves and valve angled are beat beyond touch up.
but I don't know the details on the brand and such, I do know that those retainers are 10 degree, and the grooves are conventional square cut

he showed me today that a couple of the intake valves are tuliped and .030 longer than the others because of it, and the valve angles show a big groove in them from contact with the seat

so our feeling is that we are chasing 2 problems, Detonation, and some keeper issue.

he was familiar with spring surge, but he said his experiance (largly drag racing ) with it was mostly with roller cam set ups

[ddsprint]

what is your lsa at, you may have this very tight, and not allowing the valves to close in time before, next cycle

[ddsprint]

It would be the overlap of the valves, to tight, not allowing valves enough time to close and open,

[TBRE]

Totally irrelevant...........

[hogracer3d]

Back together, got rid of the Jesel Belt Drive ( had .050) backlash , back to double roller, new dampner.
The fuel in it was apparently mixed with maybe some generator gas ( hydrometered .740) and the fuel that was supposed to be in it hyrometers at .715, drained and refilled with straight race fuel.
Changed from race pump fuel pump to conventional ProCam 6 valve.
33 degrees timing, we'll see what happens at Santa Maria

[hogracer3d]

Here we go again, 4th time.
3rd quick qualifying, won the heat, lead lap 2-8 in the main, then dead hole.

[hogracer3d]

Ran fine the week before, but was a half throttle dry slick track.
This week hooked up hammer down !

[DANNY]

Hey Dave question being the my cam is about the same lift as yours real close to 0.600 I doubt that the spring is coil binding my springs are capable of running well over 0.600 lift so I have way more room to go. As far as pressures I am #150 the seat and in the upper #400's on the nose spring pressures shouldn't be an issue either. My question is is do you know the actual quality of your keepers yes they may pass manufacture tests for standard just a maybe the same ones are always what works however is the metal actually quality enough to stand what you're putting it through in this case to be a bad batch? Is there an issue where the metal may be softer than normal or possibly too brittle? I'm just curious if you're fighting an actual product failure rather than pushing the limit too far, like I said I know I'm running pretty high pressures and I know for what we are turning we shouldn't have issues same time one thing comes to my mind is an actual product failure.

Ps: Sorry for my bad grammar and punctuation. I did this via voice text at 5:15 this morning. LOLOL

[JustAddDirt]

who set up your rocker stand heights?
are there any shims under the rocker stands?
looks like your keepers are soft, or the wrong kind for the valve cut.
what brand are your valves, and keepers? I am thinking one of the 2 are too soft. looks like it is pushing the valve threw the keeper.
might also look and make sure the roller on tip on that rocker arms is not flat spotted, and still rolls properly.

[rakracing]

had something similar happen with s.s.valves and cast heads, guides where sticking the valves a bit and the two where slapping together and hammering parts, had bronze guides installed and no problem, might be something to check.

[TBRE]

Everything mentioned will contribute to valve train problems, but, like I said in my post, the lock should NEVER slide up the valve stem unless the parts aren't right for each other. I've personally seen this on 2 occasions, one had 10 degree locks on 8 degree (Super 7) retainers, and the other was a bad set of retainers (soft). Paint the inside of the retainer taper with a magic marker, assemble it with the locks on the valve, twist it to check the fit, if it doesn't take the marker away the full length, the taper is wrong, and, the parts should stick together if the taper is close enough to each other.TB