Valve rotation a thing of the past?

[mattcfish]

I just spoke to Jerry at Northwest Connecting Rod in Seattle. He's making a bomber wasserboxer bottom end to replace my "blown to pieces" one. We got to talking about AMC heads. He says he doesn't replace the Spanish valves. He says, instead he modifies the keepers and retainers so that the valves no longer rotate and a greater clamping force is exerted on the valve stem. He has had zero problems with this. He's been doing this for over 30 years and is well respected in the VW world for knowing his stuff.
He went on to say that modern engines since the 80's no longer have rotating valves nor do many race motors. Aparently rotation was only practicle when gas was leaded.
I've done some reading on other sites and valve rotation does seem to be a thing of the past.
Any opinions on this?
_________________

[Ol'fogasaurus]

(Opinion) Back in about '65 or early '66, when we were first hearing about being mandated to go to what we referred to then as "white gas", onlythe “American” (the brand name) gas stations were selling it. Since it was fairly close to me I did try it and it did not seem to make a difference in my car. Since there was the normal spate of exaggerated rumors floating around, I went in to my local “American” dealer and talked to him about it. His take (and the same opinion from others I talked to) was that it (the fuel) would burn hotter and on your next engine rebuild you would change valves (material), new guides and seals made of material to handle the different harder material that the valves would be made from and new hard seats in the heads. I also remember being told (years before this) that one of the reasons that the valves were rotated to make the valve seats and guides(?) last longer and not oval.

So, if this is true and you have added hard seats and other upgraded goodies to your AC heads; the point of rotating valves to extend valve life may be gone (because of the harder valve seat and other stuff) so the argument does seem to make sense; especially if he is putting more seat pressure on the valves. 30 years of doing this is also hard to argue against.

Lee

[Steve Arndt]

There is high speed photography of valve-trains online. IMO it would be almost impossible to prevent the valves from rotating.

[Ol'fogasaurus]

It use to be that the valve gear was off-set to cause valve rotating. I don't know if that is still true or not.

Lee

[buildabiggerboxer]

Steve is right, the valves still rotate no matter what you do to the keepers, centered swivel feet and all wont stop them, harmonics does it, as an aside, aircooleds have had hardened valve seats from day one, all the clamped keeper idea is for is to stop grove wear on the valve with high revs, but there can be problems doing that, we've had dropped valves from shifting valve seats cocking the valve and breaking it at the collet grove, it would have survived with stock keeper play to allow the valve to swing. so theres for and against all views. sorry to go off topic a bit, but stretch bolt wasser con rods are another 'bone'...
everyone bins them, but i race them to 7000 rpm, but i also use my own theory, i dont 1/2 turn them after torque, all ive ever done is torque them to stretch a few thou" , usually about 28/30/ lb/ft, then mike and torque them till they just start to stretch, bingo. even VW can get it wrong...hope this helps. regards. bbb....

[Piledriver]

As I said in the other thread: The AMC valves/seats/guides etc should all be treated as trash.

After not many miles (assuming the AMC keepers don't pull through) the seats get pounded into the valves as they are both bubblegum or recycled bean cans. There is no point even cutting the seats...

He has a good rep, but so did Gene Berg, and we all are aware that eve the "great" can suffer from some brain dead ideas.

With decent valves/seats etc and the better rods (rebushed SCAT 5.4s w/Mahles, or 5.5s as Tencentlife prefers to use when using aftermarket pistons to set the deck properly) you should have many happy miles out of it.

Do some reading on the T5 forum, this has all been covered.

[Tom Notch]

Pretty much everybody sets the keepers to "gap" at the ends. This tends to keep things together at higher RPM and valve lift. The valves don't pull the keepers then. And yes, the valves still do some rotation, just not near as much as when the keeper floats on the stem.

Tony S. told me you scattered it big time....

I personally would upgrade the valve components, but I have no experience with the AMC heads and their seats. I put 7mm Manleys in my engine with the CB LS6 springs, CB TI retainers and the Manley single groove keepers. IIRC, These springs do require a longer valve though when running lifts over .550ish. You probably aren't that crazy on the lift.

[tencentlife]

There is high speed photography of valve-trains online. IMO it would be almost impossible to prevent the valves from rotating.

I was going to mention that, too, when you watch these high-speed clips you can see that the spring harmonics put a lot of torque into the whole assembly, there's no way you could eliminate that. And of the engines I tear apart I do typically see that the wear around the stem of the valve looks to be distributed circumferentially, i.e., they're turning.

I said typically, but then there's always the counterfactual: I opened up a wbx recenty and the stem tops had a nice covering of varnish on them in which there were bright vertical grooves that made it very clear this engine's valves hadn't rotated in quite some time, if they ever did.

So, take your pick. Some do, some don't? I dunno. Seems like most do. I'm gonna keep setting my rockers a little off-center as I always have, with the adjuster stem aligned with the valvestem at half-width. I haven't used a standard screw-tip adjuster in years, the elephant-feet leave no markings on the stems to tell one way or another, but I definitely think that for optimal seating and sealing the valves should be rotating.

The clasping of the keepers is another open question. The OEM VW keepers I check and the keepers that come with the AMC heads always meet each other, there is never a gap and they rotate freely when they are clasping a valvestem. But on engines I open up that ran with OEM valves, at least, there is no evidence that the grooves are pounding out. I think the issue there must be just the hardness of the stem material. A magnet check tells me that both OEM and AMC's exhaust valves have welded heads, both intakes are one-piece, and neither have welded stem tips. In the wbx world at least the only stories I've seen of grooves hammering out have been when the AMC intakes were used; only stories since I have no examples of my own. Since most of these are running on standard cams and valvetrain, with moderate lifts and typically low wbx rpms, I have to believe that problem must be mainly stem hardness, the cheapo valvestems are softer steel and hammer out, the higher-quality OEM materials do not. Nonetheless I grind all my keepers to leave a gap, it just makes more sense to me to eliminate that play there, whichever valves I'm using.

[mattcfish]

Tony S. told me you scattered it big time....

You might say so.




It was the 2.1 rod bolts. I snapped two of them on #2 and #4 rods at 70mph. Amazingly, the crank and cam are usable. The rest of the motor is not.
Jerry's going to use some performance ARP bolts to hold the new rods together.

So, since I need new heads anyway, Is Gowesty my best bet? $499 each isn't much more than the going rate for AMC's. I looked at buying the heads without valves, $300.00 each...but with just the TRW valves without seats I came up to the Gowesty price.
Hmmm......I guess GW doesn't replace the seats. Looks like they don't see that as a problem.

So it's just the intake valves that drop. Exhaust valves have been known to get burnt.

[tencentlife]

sorry to go off topic a bit, but stretch bolt wasser con rods are another 'bone'...
everyone bins them, but i race them to 7000 rpm, but i also use my own theory, i dont 1/2 turn them after torque, all ive ever done is torque them to stretch a few thou" , usually about 28/30/ lb/ft, then mike and torque them till they just start to stretch, bingo. even VW can get it wrong...hope this helps.

Yeah, OT I know, but you raise an interesting point. I wasn't clear on this until I did some research and learned there are no specific differences in materials or construction between Torque-to-yield and conventional fasteners. TTY is a process, not a special kind of hardware. You make a bolt a TTY when instead of tightening it within the elastic deformation limits, such that there is no permanent lengthening of the bolt, you tighten it to "yield", the beginning of plastic deformation; when relaxed, it will measure longer than it was originally. So if you reuse a TTY bolt and use the same TTY tightening process, you will have stretched it to yield a second time, with a much higher chance of failure; that's why specs typically call for one-time use only.

So if you reused the same 2.1 rod bolts, for instance, and did the same TTY tightening process, they would present a higher chance of failure, but as you say you only used a conventional torquing process that did not stretch them to yield a second time, you would have pretty good odds of avoiding failure. I say pretty good because those 2.1 wbx rod bolts do have an established record of total failure after extended use with only a single tightening, so I would bear that in mind if I intended to use any of them for a high-miles road car. I prefer, if I have to use OEM rods, to get a set out of a 1.9 where they weren't TTY-ed the first time. But then again I never use the heavy OEM rods, I've only used them twice. When I can get rods so much lighter and stronger and get brand new fasteners in the deal for so little money nowadays, even when I have to drop another $100 to enlarge and rebush the small ends, I never give used OEM rods a second thought.

That does leave the question of why the 2.1 and 1.9 rod bolts are actually different in construction, but I can only guess they chose something they thought would hold up better under a TTY regimen; just because it's a different process doesn't mean any old bolt will have the required strength. Why they preferred that when they already had a setup that worked fine, well that's more a question of corporate culture than engineering, I suspect.

[buildabiggerboxer]

tencent ,that tty theory makes sense, and my method is born of luck realy, i could get no info from VW when the 2.1 came to the UK in '85, and i started interfering with them, all they could tell me 'they are stretch bolts', so i did them as i thought right at that time, and carried on as it worked. so, yes, you are spot on, i know the history of my own stuff, and some customer builds, and they've not been 1/2 turned, which is the fatal maneuver, but truly, in your case as a pro builder and retailer, you could not risk not knowing the dark events of the past on the r/bolts. you will have to do another test engine with very old bolts and rods, barely torqued to 5 thou stretched and rev the nuts of it!! i'd better add my 2.5 has proper 3/8 race rods, and the unitecs also look a good buy for re bushing to 24mm.
Back to topic: i'm also running stock amc retainers on my 2,5, they are much better made then the German 'stamped' ones, quite nicely made and machined, and all the aftermarket T1 offerings reduce installed v/s height. also most pro builders here use the box stock amc heads, valves and all, im talking for road daily's here, and have no bad reports on the product,
thats for both wasser and T4, but i do gather they dont like gas (lpg).
i would think the hydro wasser valve gear with a gentle driver would be so kind (soft) on the spring that rotation would be less likely in your example of non rotation, ive not seen the stem groove wear T1s get on wassers either, dont forget the wasser spring is slightly larger on the o/d, may have a bearing... regards..bbb

[Tom Notch]

new bolts are always a wise move on used rods.

[Ol'fogasaurus]

I think there are bolts designed to be torque to yield and they are usually one time use bolts. Just before I retired I was in the standards and I think I saw some listed in the index.

Lee