Monday, July 6, 2009

Valve-job Tool





The Volkswagen engine uses poppet valves, as do all other cars today. The exhaust valves are the weak link in any engine but especially so in air-cooled engines, be it Pratt-Whitney or Volkswagen. If we want to keep tabs on our engine's condition all we need do is keep track of the condition of our exhaust valves since they are the first part to fail. Of course, we never allow them to fail, we merely keep track of their condition and when they tell us they are about to fail, we pull the heads and give them a 'valve job.'

To keep track of them we use the leak-down test, pulling the heads any time the leak-down is more than twenty percent or thereabouts. To do a 'valve job' means to remove the valves and restore the worn parts to spec. In about eighty percent of all cases, the worn part is the valve itself but other parts associated with the valve – the valve guide, the valve seat or the rocker arm – may also require repair or replacement. Since replacing the valves is the most frequent chore, that's what I'll talk about here, with a minor mention of the other valve-related components as we come to them.

The valve is opened by the cam but it is closed by the valve spring, which we must compress in order to remove the valve. The valve spring is held in place by a retainer and a pair of valve keepers. That is, the retainer fits down over the stem of the valve and rests on the valve spring. The stem of the valve has a pair of grooves into which the valve keepers fit. When so fitted, the valve keepers lock into the grooves and wedge into a tapered bore in the retainer, which sits on top of the valve spring. So long as the spring is in its proper position and is not damaged, the valve will not come loose, even though it may be actuated several times per second.

The valve spring is a coil-type compression spring that is progressively wound; the turns nearest the head having a higher ratio of turns per inch. This allows for easier opening. But like all springs, the Volkswagen's valve springs are effected by heat and age. VW valve springs typically take several million actuations before showing any sign of weakening. In a vehicle, the stock VW engine needs a valve job after about thirty thousand miles of service but Flying Volkswagens are rarely of stock displacement (which is less than 100 cid). Flying Volkswagens may be as large as 140 cid and their valve wear is a function of the work they do, which may be several times that of a vehicular engine. These non-stock 'Big-Bore Strokers' may need a valve job as frequently as every ten hours... or as infrequently as every two hundred hours, depending on how the engine is used.

The Volkswagen is a robust little engine that, like all Otto Cycle engines, provides a wealth of precursors of impending failure. So long as the engine is properly assembled and operated within its limitations by a pilot who has learned to recognize those clues, it is as reliable as any other engine in its class. But this puts a heavy burden on the pilot, who must be able to recognize those clues.

In an airplane the condition of the valves is determined by a leak-down test, which is performed periodically, the length of that period determined by the manner in which the engine is used. The leak-down tests (ie, wet & dry) reflects the amount of wear of the valves and rings, with the valves wearing at a much faster rate than the rings.

To perform a valve job we must remove the heads from the engine and the valves from the heads. Exhaust valves are replaced rather than reground but the intake valves may be reground and re-used.

When doing a valve job we check the valve springs against the spec in the work-shop manual. The diameter of the valve dictates the amount of spring tension needed to achieve proper closure. In specifying one valve tension but with a very wide tolerance for both the intake and the exhaust, you are seeing one of the many compromises Volkswagen made to keep down the price. For example, when the spring pressure is given as 96 lbs (+/- 6lbs) it is fair to assume that the smaller figure ( ie, 90 lbs) should be used for the exhaust and the larger figure (ie, 102 lbs) is used for the intake valves.

One of the more interesting features of the Volkswagen engine is that each lobe of the cam actuates TWO valves rather than one. That is, the intake valve of the #2 cylinder is actuated by the same cam lobe that actuates the intake valve of the #4 cylinder. The action of the cast iron cam as it wipes across the face of the cast-iron cam-followers (ie, the 'tappets') is the engine's major source of metallic residue, which in turn is the main source of wear in the engine's bearings and oil pump. To minimize this wear the wear-factor of the cam must be exactly twice that of the cam followers. The pressure of the valve spring plays a critical role in the wear-factor of the valve train as a whole.

At this point you need to go to http://home.hiwaay.net/~langford/

That's the home page of Mark Langford, who has contributed about three Ph.D's worth of information to the pool of knowledge all of us are swimming in. Specifically, I want you to read about how Mark measured his valve springs. Here in the Blog I've posted an article about a tool I made for that purpose but I was dealing with forty or fifty springs at a time. Like Mark, you are building only one engine. His method is more practical than mine.

What I want you to do is to COPY the method Mark has used for measuring his valve springs.

The assumption here is that you have only EIGHT valve springs. What you'll want to do is create the best possible match from BANK to BANK.

If you are running stock heads... meaning you are using valves of stock diameter, the spec for your valve springs is 126, +/-9 at a compressed height of 1.32". Which may be translated as 117 for your intakes and 135 for your exhaust.


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Doing a leak-down test, the 'wiggle' test and doing a valve job are common chores for those of us who flys behind a Volkswagen engine. Given that my life literally depends on the quality of the work done to my engine, it should come as no surprise that I'm unwilling to trust any work done by a mechanic who is NOT certified by some agency or authority equally concerned with the quality of his craftsmanship. Since there is no such agency for auto engines converted for flight it seems logical that I do such maintenance myself. There are a few tools specific to these tasks. They are available from most of the larger after-market retailers who specialize in VW parts. But it is the nature of the Volkswagen philosophy that the tools may also be fabricated by the individual mechanics. Volkswagen used to provide a booklet of dimensioned drawings for such tools but no longer does so.

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The first illustration in this article shows the two most recent types of valve spring retainer used on Volkswagen engines. As you can see, we need to provide for a retainer approximately 1-1/4" in diameter. Once the tool makes secure contact with the retainer we need to provide a downward force to compress the spring. It doesn't take much -- about half an inch will do. We then use a scribe or other pointed tool -- a sharpened nail will work -- to free the keepers from the grooves in the stem of the valve. Once the keepers are freed, they are removed but kept sorted according to the valve from which they came. A magnetized scriber works best or you can use a magnetic pencil.

For those of you without a metal lathe, making a tool that fits over the valve retainer is the most difficult part of the job but as you can see from the photos there are any number of workable options. And those rivets you see started out as regular nails. Just cut them off short.

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As a point of interest the Single Port (SP) head shown in the photos is a junker. The spark plugs were installed WITHOUT anti-seize compound, a necessity with regular spark plugs and ALUMINUM heads. Both of the spark plug holes have been stripped until they are almost smooth.

The shade-tree fix for a stripped spark plug hole is to install a Heli-Coil (a brand name), which is coil made of wire having a diamond-shaped cross-section. The inner diameter of the coil matches that of the spark plug whilst the outer diameter matches that of a special tap that is sold with the Heli-coils as a kit. The Heli-Coil tap is threaded into the hole WITHOUT drilling it to a larger size.

There is another type of spark plug repair kit which uses a metal sleeve having it's ID threaded for the spark plug and it's external thread of some larger diameter, usually that of a regular size. This type of repair requires the spark plug hole to be opened up to a larger size, usually with a drill. To use this type of repair kit on a Volkswagen engine that is still in the vehicle the mechanic needs to use an angle-head drill-motor or a reamer, since there isn't enough room to use a regular drill-motor. (Clearly, this does not apply to aircraft installations.)

Unfortunately, the point over looked by shade-tree mechanics is that ANY form of spark plug hole repair that involves the use of a coil or sleeve must not be used on an AIR-COOLED engine (!!) The sleeve or coil upsets the resistance -- both thermal and electrical -- of the spark plug.

The fact this type of repair is allowed on WATER-COOLED engines fitted with aluminum heads is taken by non-professional mechanics to mean the procedure may be used on ANY engine. Sadly, this is not true.

So how DO you repair a stripped spark plug hole? Working from the chamber-side of the spark plug hole you hog out a crater of generous proportions, pre-heat the head to about four hundred degrees and go at it with TIG ( or even MIG, if you've got the right equipment) ...and fill the crater with molten aluminum. The head is then put back into the oven, the oven is shut off, and the head(s) are allowed to cool to room temperature.

(Did you notice the implied plural? The plural does not refer to the fact VW engines have two heads but to the fact it is not economically practical to repair damaged heads one at a time. What you do is wait until you have about two dozen damaged heads then tool up to do them all at once.

But here in Southern California, with more than twenty-one MILLION registered vehicles(*) -- and more air-cooled Volkswagens than anywhere else in the country, there was another option.

During that period (circa 1970's) for small shops such as mine, it was worth while to find a bigger shop that regularly overhauled heads on an assembly-line basis in batches as large as 250. They would allow small shops to add their heads to the batch, inspecting them to ensure all of the preliminary work had been done, and done to their specs. They would then do ONLY the welding, charging a nominal fee.

The point here is that the proper repair of a VW head with a stripped spark plug hole is to weld it up and re-machine it. For someone FLYING behind a Volkswagen engine, if it suffers a stripped spark plug hole your best option is to replace the head, since the repair would cost more than a replacement head. But don't forget that any replacement must be an EXACT match for the old head, meaning identical chamber volume and valve train geometry.

And this time remember to apply a dab of anti-seize compound to the first few threads... and then wipe it off. The tiny amount that will remain deep in the threads is all you need.

A handy way to prevent cross-threading a spark plug is to install it full-depth using only your fingers. It will then take little more than one turn to achieve the required torque-spec (22 ft/lb). And be sure that's done with a NEW WASHER. (They've got them at the real automotive parts places; don't waste your time in those chain-store auto parts retailers.)

Finally, I recently read a post where a fellow stripped his heads because his spark plugs projected into the combustion chamber. This would NEVER happen on a properly assembled engine, where checking the projection of the plug is a standard step during pre-assembly.

If the proper plug projects too far you will want to add a solid copper washer between the regular washer and the body of the spark plug. That is, you want your new, crushable washer to be in contact with the head on at least one side. Spark plug manufacturers provide solid copper washers as well as new, crushable washers. They're usually racked in the 'Dorman's' trays (those orange & black trays taking up wall space in the back of the store) :-)

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(to be continued)

Thursday, July 2, 2009

Designing a Bigger Box

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There I am in the patio, holding steady at 151 pounds. Or 10.8 stone if you hail from across the pond. Or 68.5 kilos. Down a tad from about 235 pounds back before cancer came to call.

My height has also shrunk, apparently due to the destruction of my 3rd lumbar vertebrae; enough so that my height is now 70-1/4" instead of 72", which explains why my trousers are not only too loose but too long. Here again, the cause is due to the tumor munching away on my spine. In fact, even my feet have gotten smaller. Not in length but in most other dimensions. Which means my feet sort of rattle around in my shoes... now that the edema-like swelling is no longer a problem. (For several months the edema forced me to wear an old pair of Uggs that I'd modified with a razor, turning them into enormous slippers.) As a point of interest, the edema was a side-effect of the medication. As I became accustomed to the medication, the edema slowly went away.

Early in the history of this blog is an article about an apprentice's tool box, which was one of those tricky bits used to teach people how to rivet. A number of you, including at least one shop class, have found the tool box of sufficient interest to tackle it as a project. But more than one of you has pointed out that the dimensions of the box, while practical for tools of the 1930's, is a bit too small for tools of the 21s century. Which I pretty much ignored. After all, the project was meant to teach people how to rivet; it's functionality as a box for carrying tools was not its purpose. But when this point was raised by a third person I figured it was time to take another look at it. You can pretend that's what I'm doing in the photo above :-) (I think my wife took the snap shot to show my sister how skinny I've become.)

So I will go ahead and post a set of drawings for a bigger box; something more suitable for a modern-day kit of tools. Personally, I have not yet found the need for such a thing but judging from my mail, several of you have.

-R.S.Hoover

Monday, June 29, 2009

The Crooked Foundation


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During my last years in the Navy I was involved in what was known as the Technology Transfer Program. The idea was to pass along modern technology to friendly nations; to try and bring them up to speed in using modern-day communications and computers. I often wondered why. We were fresh out of Russians, pounding their shoe on the table at the UN, shouting they would bury us. 'Rebels' were occasionally given a polite mention.

The quotes are because it was often difficult to tell who was a rebel and who was not.

The program was a marvelous success, of course. (Have you ever heard of a government program that was not?) In fact, most of the programs were dismal failures, for reasons that were painfully evident. For example, we were tasked with teaching the operation and repair of solid-state devices to electronics technicians who had never been exposed to solid-state devices. They tried -- and there were a few who did pretty well -- we'd been given the best people they had... and 'best' was determined by how well they did with tube-type equipment, the newest being Vietnam-era junk, long since replaced by more modern equipment.

A lot of the mail I get reminds me of those 'Technology Transfer' programs. And for the same reason. For example, a message arrives from a fellow who claims to be qualified in all the basic stuff needed to maintain a VW engine, having owned his bug or bus for a number of years. In the message he provides a number of symptoms that make it clear the problem is worn valve guides, with a probability close to 100%, plus the fact that replacing the valve guides is a fairly common chore for the Volkswagen engine due to the small diameter of the valve stems and the fact air-cooled engines operate at a significantly higher temperature than their water-cooled cousins. Fortunately Volkswagen kept those things in mind when it designed the VW engine so that replacing the valve guides, which you'll need to do about every third valve job, is a straight-forward procedure, needed only a couple of additional tools.

With those things in mind I pointed the fellow toward the valve guide procedure, which I believe is fairly complete.

Unfortunately, the fellow had never done a valve job. And of course, he didn't have even the most most basic tool, the valve spring compressor, needed to dismantle the heads. His definition of Major Maintenance was replacing his clutch disk.

In the end, he bought a pair of 'rebuilt' heads from a the local 'expert' and took the first steps down the slippery slope that eventually lead to him getting rid of his Volkswagen.

Ditto for Flying Volkswagens, except that first step is liable to happen within a matter of hours rather than years. Why? Because a flying Volkswagen is liable to be operated for hours at a time at a level of output rarely seen in a bug or bus. The tricky bit here is the belief that all rpm's are the same; that running 3600 rpm in a plane will be the same as running 3600 rpm in a car. It isn't... unless the manifold pressure happens to be the same as well. The bottom line is that you can literally wear out a VW engine in a matter of hours.

Which isn't especially bad, assuming you understand what you are doing and keep a spare set of heads on hand.

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I'm a bit more circumspect nowadays, with people having assembled an engine from a kit of parts. Do you have a valve spring compressor? A rack to hold the removed valves? Do you have these foundation tools? Because if you don't, you'd better get them. You can buy them or make them but you absolutely can not do without them. These tools are the foundation of engine maintenace and to do without them is to build on a crooked foundation; things simply can not come out true.

This article shows a fixture for holding valves. These happen to be made of wood but you can make them from cardboard, assembled with duct tape, or scrap aluminum if you'd like a simple riveting project. But I like to work with wood and had some scrap handy....

Thursday, June 18, 2009

CANCEROUS VOLKSWAGENS

This is a red 'loaf, I think a '71. No engine installed but it's on its own wheels. Used for storage so some stuff has to come out before it can go. There might be a Type IV stored in it -- I haven't been into it in more than a year.










There is a small propane tank for this one. Lotsa junk inside.


This is the one down in the field. No running gear but trick upholstery. Loaded with junk. Needs to be skidded onto a flat-bed... after removing the vehicles in front of it.




That's Grendle. I patched her floor & door jams, did some work to the nose & cockpit (floor was rusted out). Front axle is removed for overhaul... which never happened. Ditto for engine, except it was a swap; the core engine is still here, plus the tranny & aft running gear. The running gear could be re-installed in a couple of days but it's a long way from running -- needs a fuel tank & plumbing, for example, plus I haven't finished the doors.


There is a nose clip down in the field which was for this vehicle but now it's a case of winner take all. There's a shot of her nose.

Wednesday, June 17, 2009

HVX_MODS WARNING !

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TO ALL:

In doing the HVX mods you must drill two holes which result in the connection of the right-side tappet oil gallery to the #3 cam bearing.

THIS DRILLING IS CRITICAL!

On some engines there is not enough metal to allow the two new holes to connect without breaking through to the outside of the crankcase. THIS WILL DESTROY THE CRANKCASE.

Before doing the drilling you must make sure there is enough metal. A warning to that effect has been on the drawings since they were first uploaded but in some cases it is difficult to take an accurate measurement, in others the builder lacks the proper tools.

-R.S.Hoover

Saturday, June 13, 2009

What's the Secret?

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In addition to the Comments attached to to the tail-end of every Blog entry, a lot of folks contact me directly via email ( veeduber@chuggers.net ) In response to my last Blog entry ('Good News!' ) I received several email messages. One of them sounded a bit forlorn... and failed to provide a valid email address, making it impossible to answer them directly. What they wanted to know was the 'secret' of receiving good medical care.

I don't think there is a secret. But I think a lot of people have failed to understand the realities of modern medical treatment and a good way to prove that is to take a look at medical treatment in the past. You know the ones I mean.... where the Hero gets sick and ends up in the hospital attended to by the modern-day version of Florence Nightingale, where the All-Knowing physician apparently lived in a room just down the hall. The Hero's medical record -- magically reduced to a single sheet of paper attached to a clip-board hanging on the foot of the bed -- contained everything doctor might want to know.

You can get a good laugh out of some present-day hospitals, the ones where the nurses don't even speak English and the physician might only come around one day per week. My case will give you a nice example of modern-day medical treatment, where the patient becomes their own hospital.

As most of you know, I have Multiple Myeloma, a form of blood cancer for which there is no cure, although it can be treated. The fellow who wrote me is apparently dealing with medical problems of his own, wondering what's the secret to getting a bit of good news.

Although I don't believe there is any secret, the difference between my treatment and his could very well be the quality of the hospital he uses, which is a play upon words since, as I've said above, in the modern day we often become our own hospital.

See that clip-board hanging on the foot of the patient's bed? Back in the Good Ol' Days... whenever that was, that was the patient's 'Vitals Chart' and listed the patient's pulse-rate and temperature, recorded however often the doctor requested it, with every four hours being typical. Nowadays your vitals usually present more data, such as blood pressure and the oxygen content of your blood. Being my own hospital, I collect & record my own vitals, generally using modern electronic instruments. As a pilot I already had a Nonin (brand name) blood-oxygen instrument, and the electronic thermometer seemed to arrive along with the kids. But I had to buy an electronic blood pressure device (less than $20).

I usually take my vitals every day. The data is recorded in a notebook and again into a computer file. The notebook makes the data portable, allowing the physician to see it, should they ask. But most doctor's offices prefer to record your vitals themselves.

I also record my weight, usually after my shower.

My pills follow a four-times-per-day schedule. There is a listing that shows what medications I take, how much, and when they are taken. There is also an 'Origination List' showing which physician prescribed which pills, what they are for and when they were prescribed. Making sure this list up to date is a basic chore each time we visit any of the five doctors. Since my ailment is being treated by a team of physicians, it's up to me to ensure that all are made aware of any change to my mediations, especially when there is the possibility of any drug interaction.

Many cancer patients say the cure is often worse than the disease. I've got a hunch they need to spend more time talking to their physician because a slight change in dosage or frequency can eliminate many of the side-effects which give rise to such claims. (In my case there isn't any cure, but that doesn't mean it has to be fatal.) Working with the physicians over the past year has resulted in a nice balance of medications which has reduced the side-effects to little more than a nuisance. That doesn't mean a full recovery -- the tumor has caused too much damage for that. But neither does it have me puttering about in a wheel chair. In either case, each of us is the master of our fate. For someone to feel that good medical care involves some secret is more likely to cause others to doubt the person's perceptions than the quality of their physician. On the other hand, over the last few years there has been enormous strides in medicine and some physicians have failed to keep pace. If the cure is indeed so terrible it would seem logical to seek a second opinion.

Personally, if there is any secret it probably has to do with the cooperation between the physicians and the patients, with the patient playing the major cooperative role. Physicians simply have too many depands upon their time. From the outset of my treatment Dr. Bessudo, my oncologist, insisted upon a team approach, calling upon other physicians as needed. He also said that I would be a part of the team but I didn't realize what that role entailed. Looking back on the past year it is now obvious that much of my progress was due entirely to the roles played by my wife and myself. While that may sound self-serving I can swear it is not.

In effect, my hospital covers about 200 square miles (!). In the past year my wife has never failed to deliver me to the proper physician, on time and suitably attired. (Indeed, she uses a check-off list to ensure I have wallet, cell-phone and so forth -- ten items, all tolled.) Nor has she failed to procure my medications, and to dole them out in the proper frequency, from once a day to once per week. I suspect support of this nature is not considered much of a secret when in fact it forms the very foundation of my treatment.

A recommended change to my medication appears automatically on the other physician's computers, supported by an often cryptic email. Often times a recommended change will produce a flurry of emails before the matter is resolved, often based on economic factors. (You won't believe what some drugs cost!) New drugs come on the market every day and if your ailment matches the intended purpose of the drug you're liable to be used as something of a lab-rat. Before trying something new, if you are being treated by more than one physician, it's a good idea to make sure they are all aware of the new drug and any possible side effects. This kind of information is available in the Physician's Desk Reference (PDR) and from the company offering the new drug. The key point here is that you... YOU need to devote some time to your treatment. As I've said, physicians are busy people. Your treatment must be a cooperative effort.

Baffled by all those medical terms? Then write them down. Now go look them up on your computer. Learn how to pronounce them properly. Write down any questions you may have. Rehearse your visit to the doctor. Be concise! Don't waste her time. (Nor his.)

Are these things secrets? I don't think so. Indeed, I've a hunch your physician will appreciate your enlightened interest.

-R.S.Hoover

Tuesday, June 9, 2009

Great Day!

Just back from the Doctor Shop. This was the internist, Dr. Kipper. Turns out, he has not been getting copies of my blood-work from the lab. (The lab's computer zips the copies out to whoever is on the list. For some reason it has not been zipping. Now it is.)

He does his thing; stethoscope, poke'm here, poke'm there... "DEEP breath... no, a really deep breath..." and I'm breathing so hard the wallpaper is starting to blister. Doesn't believe the girls figures perhaps.

Hems & haws and finally tells me: 'Get outta here. Come see me in three or four months."

So the physicians are all in agreement: I'm pregnant. Or mebbe not :-) But I'm certainly not suffering from a cancerous tumor. Oh, it's there. And it has already done its dirty work. But except for the back pain I am not suffering from it. It has not spread; it is not eating me alive.
This is GOOD NEWS . And I am happy to share it with you.

There is still the pain, of course, kept in check by a careful balance of pain-killers. If I try to do too much -- and I have, a time or two. I have a Magic Elixer called 'No Pain' that I can rub on the spot which does a nice job if the pain is not too large. But keep pushing the envelop and the pain will eventually break through. By the time it does, it's no laughing matter -- the magnitude is 'way out there and nothing works except a shot or more pain pills... which knocks me out. And if I'm not near a bed when that happens, it can be a major inconvenience.

But today was a good day. One I wanted to share with you.

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I'm still working on the Portable/Table Saw project. I wasted a week tracking down some sanding disks. Then we had a spate of rain (!!). Unheard of this late in the year. Then there were house chores... yada, yada, yada.

And the worry. Which is kinda funny.

I've got cancer. But I feel pretty good and find myself worrying about that. Think about it for a minute. The main problem is that I've not yet gotten to the point where I can shrug my shoulders and get on with my life. After all, Cancer is Bad. So I shouldn't be feeling Good.

Crazy, eh?

-R.S.Hoover
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