Swivel-Foot Valve Adjusters

[gammaxy]

1) Is this done to compensate for the VW's lack of a valve rotater?
2) If so, would the elephant foot adjusters be able to provide the same function?

I've asked the same question before. It seems the reason is to provide rotation, but I've never seen any evidence in my engine that the valves rotate. Every valve stem has marks where the swivel foot has rubbed, but they're confined to one side of the valve stem with no evidence of rotation. I don't think there's enough friction between the face of the ball and the stem to induce rotation.

After reading about some car people's experience with the ball getting pounded through the elephant foot adjuster, I've decided to give the expensive Porsche adjusters a try. Haven't yet received them, though.
https://www.pelicanparts.com/More_Info/ ... 370-02-INT

Here's a thread comparing some of the elephant foot adjusters:
https://www.thesamba.com/vw/forum/viewt ... p?t=548025

There have been some adjuster failures mentioned on the forum. The only one I'm aware of that's been well documented involved incorrect installation. Others have mentioned failures where they were believed to be installed correctly, so I think this might be an area where either better parts, more frequent replacement, or more careful installation is warranted. Curious if anyone has simply installed stock adjusters with no moving parts to wear out.

[bvolcko38]

I agree, no evidence of rotation on my valves either.

[Onex107]

I know you have to get the flat spot on the ball facing the valve stem, but how did you get enough gap to let the ball fall out of the pocket with .004 to .006 valve clearance?

[gammaxy]

how did you get enough gap to let the ball fall out of the pocket with .004 to .006 valve clearance?

I removed the rocker arms to check the torque on the cylinder head nuts. Once I removed the arms, one ball fell out. When inspecting the others, a few others came out easily using a magnet. I suspect I could have continued to fly in this condition for quite a while, but it just seemed wrong to be one brief stuck valve away from the ball possibly falling out. This might be an irrational fear since wouldn't such a stuck valve also possibly allow the pushrod to fall out of position anyway?

This really would have been no big deal to me and I would have happily replaced them with 8 new ones and just started replacing them every 200 hours or so, but I have no good way to tell if the 8 new ones will open me up to the possibility of a catastrophic failure (given the other failures recently mentioned on this forum). Mine are the SCAT parts supplied by Sonex (as I learned from Mark's post below).

I bought and installed the expensive Porsche ones, but I've only flown on them for 30 minutes so far. Need to get back to the plane and do a post flight inspection to verify there were no significant issues with them.

[DCASonex]

As to ball falling out with only a few thousandths clearance: A briefly sticking valve would increase the clearance enough to let the ball fall out, possibly during startup, but not becoming evident until takeoff or into the flight.

David A.

[markschaible]

Hello SonexBuilders.net and Happy New Year to all!

A few thoughts for you from the factory on this thread:

• We've been exclusively supplying SCAT brand rocker assemblies with swivel feet since approximately 2006. Prior to that we supplied CB 1640 "Rhino Rocker" parts which had elephant feet. All parts in the VW aftermarket parts supply chain change over-time, even when sourcing the same part number from the same supplier. A benign example: rocker arms on the assemblies we currently have in-stock are now gold in-color (Cad-plated). The nature of the worldwide VW parts supply is that quality can migrate between production runs from a given supplier and over-time. We do our best to stay on-top of these quality migrations.
• We have received a report from at-least one customer and some anecdotal reports that some customers are using smaller valve clearance -- almost no clearance in some cases. While valve clearance is hotly debated in the VW world with some performance VW folks shimming as tight as .001", standard guidance for ball swivel (Courier) adjusters is that they must have lash for proper lubrication. Our published clearances must be followed. Variations of the clearances are undertaken at your own risk to engine performance and reliability.
• It is our opinion, based on over-all customer reports, that the elephant foot adjusters fail far more frequently than the swivel foot adjusters. The elephant foot adjusters have been found sheared off the ends of their adjuster as well as split from being beaten against the valve stems. Not maintaining proper valve adjustment is a contributing factor to these failures.

[pappas]

Mark,

Thanks for the input. Always good to have responses from you guys. As for myself, I have never heard about the practice to change valve lash clearance from the factory recommended to something else. I know that the valve clearances I had set on my engine were always at .008 for intake and .014 for exhaust. The adjuster lock nut and adjuster stem were still locked down and secure against the rocker arm. They took a lot of pictures of all that.

The NTSB sent my right-hand rocker assembly as well as the broken adjuster parts to their metallurgical lab for analysis. It will be nice to know, eventually, why this part failed. I'm still scratching my head.

[karmarepair]

As for myself, I have never heard about the practice to change valve lash clearance from the factory recommended to something else. I know that the valve clearances I had set on my engine were always at .008 for intake and .014 for exhaust.

I don't have my Aerovee engine manual handy, but that seems like a lot of valve clearance, particularly for an engine with steel push rods.

As the case, barrels, and heads get hot, the engine gets wider. The stock aluminum pushrods get longer, so the lash stays more or less the same. On our engines, with more cam lift and stronger valve springs, we use STEEL pushrods, which do NOT get longer as fast as aluminum, thus the valve lash opens up as the engine gets hot. Car guys that run steel pushrods reduce the COLD valve clearance, so that it won't be too much HOT, and typically set it at zero to .002". Typical suggestions for aluminum pushrods are .004" to .006" cold.

Even though my new to me but circa 2000 engine (naturally aspirated) has steel pushrods, and unless the manual says otherwise, I'm sticking with .006" (which is what Steve Bennet of Great Plains suggests).

Too much clearance means the valves will likely clatter and, over the long term, may damage the valves, camshaft lobes, tappets. And possibly the adjusters...

LATER EDIT: It looks like the factory indeed recommends that big exhaust valve clearance for the turbo. The other effect I didn't mention is the heating of the valve itself, which causes the stem to "stretch". I guess on the turbo the exhaust valves run so hot this is necessary. I'm leaving this post up, for the Good Of The Order, but Lou WAS running the Aerovee recommended clearance. Off to dig for the Naturally Aspirated manual to see what it says....

[Curry Matherne]

The manual for the NA engine says .006

[rizzz]

Why is the clearance higher on the turbo? Is the expectation that there is more expansion because of the extra heat generated by the turbo or is this done to achieve longer valve closure times without having to use a different camshaft?