experiences with elephant foot valve adjusters??

[n502pd]

I have been watchin g failures of the aero vee, and several appear to have had the swivel foot adjusters fail for some reason. I am just about to remove mine and put in a set of elephant foot adjusters, but would desire some feed back on those who have used them. How long in use, any problems what so ever, any outright failures, that sort of thing. Lastly, from whom did you get the e-foot adjusters? the specs I find show they are 8 mm, but do not specify if they are 8x1.25 , or 8x1.0 thread specs. Standard swivel foot ones I have are 8x1.0. Anybody with more info, recomendations on sourcing?

Thanks much!

[Curry Matherne]

https://www.cbperformance.com/product-p/1684.htm

After reading about the one that went down the other day I took the easy route and ordered the above. It comes with the elephant foot type adjuster.
I currently have the ball type and they still look good but I don't want to take the chance.

[pappas]

As everyone knows, I have been looking into this as well. I was thinking I would go with the Elephant foot pads as well. Not because I know them to be better, but simply because I had a bad experience with the ball swivel pads.

I have been speaking to a few others and it was mentioned that Revmaster doesn't even use a swivel pad adjuster of any kind. They simply use the stock VW adjuster which is only a threaded rod with no pad. Our rockers are a 1:1 ratio. I will likely keep that ratio. Apparently, there are other Aerovee users that have gone that route as well.

Any thoughts?

[Scott Todd]

I just googled VW valve adjuster and came up with a few. I ordered a set to see what they look like. I can see where a car enthusiasts wants the ultimate performance and people always want new shiny upgrades to impress their friends. But for airplanes, we need to minimize moving parts and keep them as simple as possible.

It totally makes sense to use the originals. Even changing them every 100 hours or so if they wear is economical.

Thanks for the heads up Lou. Anyone else have any experience with these original adjusters?

[Area 51%]

The service life of a VW head of any description in aircraft service seems to be 500hrs or less. Hardly enough time for adjusters of any style to have much of an impact on the tops of the valve stems.

Apples and oranges aside, I currently have 70,000 miles on my street buggy's rebuilt engine that included new heads and stock style valve adjusters. They get adjusted at every 1500mi oil change. At an average speed of 50mph, that's 1400 hours with the valve stems finally showing a light "dish" from contact wear and no appreciable stem-to-guide wear from side loading. Adding oil between changes has never been necessary, so there's not much getting past the valve stems.
But like swivel feet, not all stock-style adjusters are created equal. If you go in that direction, look for adjusters that have a large radius rather than the type that has an 8mm hemisphere machined into their end.

CB Performance swivel adjusters currently grace the ends of my CB rocker arms (The Empi rocker shafts were mis-drilled and wouldn't go over the studs, so were replaced with CB units listed in this thread). I had already sized the pushrods for the Empi ball adjusters that came in the engine kit when reports started surfacing about failures of those units. It made sense to simply go with a quality replacement that didn't require any other modification. (I still have the unused Empi adjusters if anyone is suicidal).
Elephant feet are on the bench, waiting for the next required head torquing to be installed. No structural concerns here. Just tired of chasing the little flat spot around on the ball adjusters.

I'm going with stock-style adjusters on my next engine.

[radfordc]

Some years ago I was checking the valve adjustment on my Aerovee and found one of the adjusters broken. Luckily, the broken "foot" had remained in place.

[karmarepair]

This is going to be long, I hope it's helpful.

R.S. Hoover was a friend, and a mentor. I've edited it lightly, to eliminate some outdated stuff, either extinct sources, or areas where "Veeduber" changed his mind in the decade I knew him.

Subject: Veedubs, Valve lash and Chunkie Attacks
Date: Fri, 12 Jan 2001 10:46:04 -0800
From: veeduber@pacbell.net
Reply-To: VW@lists.kz
To: VW@lists.kz

To All:

The following is an excerpt from Part V of the VW
Engine series, originally posted to the Teenie Two
forum on 21 October 2000. If you are experienced
with aircooled engines you won't find anything new
in the series of articles (50+ pages so far). Nor
will you find anything that is not in the factory
manuals or real books by real authorities such as
Ricardo or Taylor. The usefulness of the articles
is that they specifically address how to make the
VW engine fly.

-R.S.Hoover
-------------------------------------------------

SWIVEL-FOOT ADJUSTING SCREWS

The valve adjusting screw used by Volkswagen has a
cambered face, a segment of a sphere.

The rocker arm is an elegantly designed little
lever. Forged from mild steel, it has a ball
socket on one end to accept the push-rod and a
threaded bore on the other for
the adjusting screw. An oil passageway is drilled
from the root of the ball socket to the rocker shaft bore, and from
the threaded adjusting screw bore to the rocker
shaft bore. After the oil passageway is drilled, the outer openings are
sealed, one by swaging the other with a dot of
weld. In use, pressurized oil from the hollow push-rod is forced
through the drilling to lubricate the assembly.

To actuate the valve, to push it down against the
pressure of the spring, the rocker swipes the
adjusting screw across the stem-face of the valve in an arc having a
radius of about an inch and a quarter. The valve
guide isn't perpendicular to the head, it's pointing ëdownhill' toward the
rocker shaft at an angle of about 9.5 degrees.
(See the illustrations in the factory workshop manual. This angle is
critical. For doing any serious head work, all of
your jigs & fixtures must take it into account.) Because of the angled
position of the valve the adjusting screw remains
in contact with the stem-face even though the adjusting screw is
swinging through an arc. And as it swings through
that arc, it pushes the valve down about four tenths of an inch.

The adjusting screw does not push down on the
exact center of the stem-face, but about half way
between the center and the edge of the valve stem, at about the 3
o'clock position. Because of the swiping motion,
that eccentric point of contact causes the valve to rotate. When the
spring pops the valve closed, the valve will
present a new sealing surface to the valve seat, equalizing wear and
insuring a better seal. Similar geometry is used
by the cam to impart rotary motion to the cam-followers. That motion
serves to distribute the wear of these linear
reciprocating parts. Without it, the valve guides and cam follower
bores would wear out of spec in a matter of hours.

The problem is that adjusting screw. Or rather,
it's cambered face.

A sphere can only contact a flat surface at one
point. All of the pressure to actuate the valve is
focused on that single, tiny point of contact. The valve doesn't mind.
After all, the face of the stem is hardened. But
the adjusting screw is not. And wears according.

The adjusting screw begins to wear the instant it
makes contact with the valve and continues to do
so until there is such an obvious gap between the two you can hear
them clack as they come together. That's when you
adjust the valves. And the "When" is about every twenty hours
of engine operation.

The interesting point here is that the wear
produces a flat face on the adjusting screw. As
the wear progresses the flat
face becomes larger and the RATE of wear
decreases. Unfortunately, the hammering effect of
the increased gap more than offsets the slower rate of wear.

To 'adjust the valves' means to loosen the
adjusting screw locknut and rotate the adjusting
screw with a screwdriver so as to be an UNWORN face of its spherical tip
into contact with the valve stem. No problem. Once
you get the hang of it you'll be able to adjust all eight valves in
fifteen minutes or less.

And then do it again about 20 hours later. And
again. And again.

After the fourth or fifth valve adjustment the
cambered face of the adjusting screw is no longer
a segment of a sphere, it has become faceted with flats like a crudely
cut diamond. The bad news is that the interface
between those faceted flats forms a dull knife-edge.

Adjust the valves so as to bring one of those
knife-edges into contact with the valve stem and
two things happen. The first is that the narrow knife-edge wears down at
a surprising rate, a matter of minutes if the edge
is especially narrow. Adjust the valves and they are OUT of
adjustment within the first five miles. The second
thing that happens is that the knife edge exerts sufficient force to
begin wearing a groove into the face of the valve
stem. If you don't do something about it, the wear will reach such an
extent that the valve stem will take on the
appearance of a mushroom and chunks of the edge will actually break off...
and find their way into your oil pump.

That's why the Volkswagen manual tells the
mechanic to replace the adjusting screw ëas
required,' which works out to
about every fourth or fifth adjustment.

Back in the Good Old Days, whenever that was, the
Parts Guy (who was often a girl but still a Guy)
kept sets of eight adjusting screws bagged & handy right there at the
counter. You'd lean around the door, say
'Adjusters?' and find eight of them in your hand, just that quick.

I should mention here that a point-contact type of
valve adjuster is not a good idea. It's only
advantage is low initial cost. But back then, the labor of their
replacement didn't enter into it, not when a
qualified VW mechanic earned less
than a dollar an hour.

Periodic replacement of the adjusting screws isn't
a big deal. So long as you DO replace them. Let
them go and, believe it or not, they can cost you an engine.
Those chunkies that break off the valve stem?
They're as hard as glass and some are small enough to pass through the
screen protecting the oil pick-up tube. Once they
get into the oil pump, the engine is doomed.

Back in the mid-1950's the engineers at Ford of
Germany came up with an adjusting screw for their
engines that used a captive-ball arrangement. Everyone who owned a
VW and did their own work (not a bunch, back then)
immediately bought a set of those marvelous
adjusters, modified their rocker arms to accept them, and
breathed an enormous sigh of relief. Not only had
we just saved ourselves a couple hours a year in
maintenance time, we'd removed the threat of Chunkie Attacks on our
oil pump.

The captive-ball arrangement presents a flat face
to the stem of the valve. The wiping motion and
valve rotation is still there but accommodated by the swiveling of
the spherical upper surface of the captive ball,
the flat lower surface providing the contact with the valve. Now we could
adjust our valves and have them STAY in adjustment
for up to a year, thanks to the lower wear rate resulting from
the enormous increase in contact surface area.

The Ford-type of swivel-foot adjuster restrains
the ball within a metal ring. The ball is
internally lubricated by a drilling
that communicates with the drilled oil passageway
in the rocker arm. The ball is fairly large and
the metal ring that captures it even larger, making the thing too
thick to fit a stock VW rocker.

So you modify the rocker.

The elegant way is to make a little jig for the
milling machine and remove about sixty thou from
the end of the rocker's threaded bore using a piloted end-mill
having a nice radius. Once you've got things set
up it takes less than a minute to modify a rocker. (Alas, my milling
machine is an antique Van Norman #12. No quill
feed. So I made a little
rig for the lathe and used that.)

The other way is to rub the thing against the
grinder until it fits.

Either way will work and the grindstone method
isn't especially dangerous if you carefully flat
the ground area then polish it, so as not to give cracks a chance to
start.

But swivel foot adjusters are longer than stock
adjusters. And you can't keep grinding away the
rocker arm. So once you get the adjuster to fit the rocker arm, you
RAISE the rocker shaft. How much? That depends on
your valve stem length but in most cases, about another sixty
thou.

Gene Berg Enterprises makes a different type of
swivel foot adjuster in which the ball is smaller
than the Ford type..
The Berg adjuster is shorter than the Ford type
but still longer than stock. You don't need to
modify your rocker arms but you do need to raise
the rocker shaft a bit.
Suitable shims come with the adjusters.

There is an after-market copy of the Berg adjuster
but the quality is pretty bad - you'll need to
stone them flat to get them to work.

I've installed perhaps a hundred sets of the Berg
type on auto engines and have had a couple of
failures. I mentioned the failures to Gene. He
told me he'd never heard of his adjusters ever failing.
He said this both times I mentioned it
to him :-) (Gene has passed on. He is sorely
missed.)

For airplane engines, I use the Ford type. I've
never had one fail. Nor have I ever heard of one
failing.

Gene Berg Enterprises advertises in the
VW-specific magazines. Most after-market VW
retailers carry the Ford type;

A NOTE ON VALVE ADJUSTMENT

The ideal valve lash is zero.

We use something larger than zero because the
engine expands as it reaches operating
temperature. The amount of
lash we set with the engine cold, typically .004"
of clearance for the intake valves and .006" for
the exhaust, reflects an educated guess as to how much expansion is
going to take place. The above figures are the
factory specs for the stock engine.

Being an inch or more wider than the stock engine,
big-bore strokers need longer push-rods and the
type most commonly available are made of alloy steel tubing.
Stock push-rods are aluminum tubing with steel
fittings swaged into each end.

For a given temperature, aluminum expands more
than steel. When using steel push-rods you'll
typically find the best valve clearance to be something LESS than the
factory spec..

[karmarepair]

The other thing my mentor did on his engines was greatly increase the flow of oil to the heads.

The What and Why http://bobhooversblog.blogspot.com/2007 ... -mods.html

The How http://bobhooversblog.blogspot.com/2009 ... to-it.html
http://bobhooversblog.blogspot.com/2007 ... again.html
http://users.lmi.net/~ryoung/Sonerai/HVX_Mods.html - the links in this page are almost certainly dead.

[bvolcko38]

I would love to see a picture of the VW factory manual page showing the geometry between the adjuster and the valve stem. I wonder, does this apply to the Aerovee ball type rocker?

[pappas]

This is interesting and informative. Thanks for that post. The thing we want to zero in on is, exactly what parts should we use and where do we get them?

For aircraft, Hoover recommended using the "Ford" part which is the captive ball with a flat surface in a captive ring. But ours have failed. Where do we get a "better" Ford type?

Hoover says, "Most after-market VW retailers carry the Ford type". But no one is advertising "Ford Type" adjusters for a VW. The search continues! Help us!