With Wings As Eagles: Craig P. Steffen's Blog

Never Done That Before

2012 April 24 07:50

I took a work trip to Pittsburgh, PA last week. It was for a computer training seminar, so I spent it indoors without much chance to take photos.

I noticed a rather odd thing driving up. All the way across eastern Ohio, there are signs for the city of "Wheeling", which is a small-ish city on the east end of I-70 within Ohio. Just across the border into Pennsyvania is the Pittsburgh metro area, which is much larger and would make a much more logical choice for "this highway to" signs. I presume some Ohio administrator decided at some point that they didn't want to point people to a city in aother state, no matter how large or prominent.

It was a rather dreary cloudy day, so my phone camera wasn't coping very well with the low light. That coupled with the fact that take these photos use-the-force point-and-shoot style meant that I didn't get very many usable photos at all. Here are a couple from the drive up:

My purpose for this post is this photo. I'm told this buildin in central Pittsburgh is called "The Cathedral of Learning"; I think it's a building in the University of Pittsburgh. It's really quite something. I hope I get a chance to go inside sometime.

Mechanic In Charge

2012 April 23 23:03

The late lamented RS "Bob" Hoover (the VW guy, not the famous pilot) was fond of saying that "your'e the mechanic in charge". My take on what he meant was that no matter what any expert may tell you, you're the person on the spot who has the ability to see what's what. You're ultimately responsible for your work, not the people on the internet trying to give you advice.

I try very hard to keep those words in mind when I work on my vintage VW. The problem with any vintage vehicle is it has a mix of old and new parts, and both sets have been maintained by different people with different levels of skill and care. ANY time you install or replace anything in a vintage car, it's vital that you don't just slap it on, you must work mentally work through what that thing is going to do, and how it relates to the parts around it. You need to anticipate what might to wrong and investigate it (by moving the part, or checking the configuration, or whatever). If you just fasten it on and don't think about it, if it turns out to be NOT an identical replacement, it will fail or jam at the most imopportune moment. Then you'll be faced with digging out the error and figuring out what you did wrong and then put it back.

My case in point was carburetor floats. I assumed they were all the same. I've dis-assembled and re-assembled carbs at least a dozen times since I've owned my vintage VW, and up until last year, the float wasn't something I ever thought about. Last year, I did a few hundred miles of test drive in my car. In preparation for doing so, I assembled a carburetor, just like I had many times before. I drove it on several test drives, ending with a 200 mile drive that included about 30 miles on the interstate. The next time I drove the car, a few days later, I backed it out of the garage, it died and wouldn't start. I spent the next week fighting with the carburetor and fuel pump. I'll use a more recent carburetor to illustrate what happened.

Here's one of the recent carburetors that I've built. Although the float bowl is dry, I'm holding it up at the hinge so that it sits about horizontally, where it would sit if there was gasoline in the bowl. You're looking down at the float bowl; the top half of the carburetor is removed. The float is the dark colored rectangular piece; its upper corners are marked with green dots.

The float can slide a little bit to the right and left on its hinge pin, but it's in no danger of scraping the sides of the float bowl (marked with red dots). The float can ride up and down freely (fit and function).

The trouble I had last year with the carburetor build was it seems there are multiple sizes of carburetor floats of this type in the world. The float of the carb that I had a problem with just just a teeny bit longer (about 1.3mm longer, IIRC); its far edge was about where the red line is marked on the same photo:

You'll notice that the upper left corner is very near the edge of the float bowl. What had happened was I'd put in a slightly larger float without realizing it. I didn't thorougly check its range of motion. I then drive the car several times, including a long trip, and had no trouble. Suddenly, one day, the float drifted to the left a bit, scraped the edge of the bowl and sort of wedged there. When the float is in its upper position, it closes the needle valve so no gas goes in. So the engine wasnt' getting gas.

I have no idea why there is a different size of carburetor float; maybe its for a completely different carburetor, but someone happened to put it in a VW carb, and so it ended up in my parts bin. But I didn't carefully check its fit, and that could have stranded me somewhere.

Mr Scott, There Will Be No Refit

2012 April 23 22:03

Last Tuesday, the Space Shuttle Discovery flew on its carrier aircraft from Cape Kennedy in Florida to Dulles Airport near Washington DC, where it will be housed at the Udvar Hazy branch of the Smithsonian Air and Space Museum.

Here they are taxiing out (I watched the takeoff on TV; the photos are of the screen)

And takeoff!

The Discovery is special for several reasons that I won't go into. She is currently the longest lived space vehicle that's ever returned to eath (space stations last much longer, but they don't re-enter intact). Discovery logged just over year in space total.

The other reason is when I visited NASA's vehicle assembly building, Discovery was sitting in one of the vertical bays awaiting transport:

(This photo is of me, with my mobile, with Discovery in the background, taken by someone else on the tour.) Sorry for the scruffy face. I'd planned to stay in a hotel the night before during my drive, but it seems that every hotel in the entire northern half of the state of Florida was booked that night, so I ended up sleeping in my car at a rest stop.

Quick Look Back

2012 April 23 21:51

There was a Mooney fly-in event at the Tennessee Museum Of Aviation last February. My wife and I went along to meet people, see the museum, and do the sit-in-the-cockpit game with some folks that I'd talked to before ahead of time.

My experience with our club's Cessna aircraft was that an iPad didn't fit between the yoke horns. It seems that a Mooney yoke is wider; it fits fine:

The museum itself has the usual stuff; engines, vintage fighters. There's a fairly old Willy's Jeep, which was kind of cool. What completely surprised me coming around a corner at the back side of the museum was this:

It's a full-scale model that someone made of the Airwolf helicopter from the television show. The creator took a Bell 222 (upon which the "real" Airwolf was based), made it into a model, then donated it to the museum. It was utterly unexpected and I was totally floored. It's nice to be surprised sometimes.

resonance 2, me 0

2012 April 22 09:02

We keep having periodic humming in our pipes. STILL. We it in the pipes when we moved in, and the water company guy told us we needed to have the restrictor valve replaced. We did that, and it changed. And mostly went away. But for the last year, it's been happening with much more frequency.

I'd convinced myself that it was because we had a long horizontal pipe run between the entrance to the house and where it starts feeding fixtures in the house. So I put a U-bend in the pipe right in the middle of that run:

Well, that didn't work. I dont' think it even modified it much. I'm gratified that I was able to splice a fairly major piece of pipe in the middle of a run in PVC, but it didn't achieve its purpose.

We discovered that the U-bend didn't fix it just as I was about to leave the house on a trip. One major difficulty with this series of problems is that the phenomenon is very difficult to reproduce reiliably. Even when it's doing it, sometimes it won't happen for days at a time, so it's very difficult to be able to go down there when it's happening.

When it did it again, I went downstairs, and realized that the source of the vibration itself seems to be a point just after the entrance to the house. If I held my hand firmly on the elbow, it would stop all together. So as a stop-gap, I tied two heavy objects to the pipe near that point to try to dampen the vibrations:

I used the book-end and the camshaft because they were handy. The book-end is upside-down because that way it doesn't slide off of the cable tie.

I'm not sure when round 3 will be. If damping the vibrations by tying things to the pipe doesn't work, then we may need to call a plumber out again and try to find the problem for real.

Some Carburetor Details

2012 April 21 10:44

And now an excuse for some pretty pictures.

For those who don't know the specifics, a carburetor is a fuel metering device. In a carbureted car, the air coming into the engine goes through the carburetor before going to the cylinders. The carburetor mixes fuel mist into the air stream so that the air/fuel mixture that arrives in the cylinders has the proper ratio to burn and drive the engine. Carburetors are sort of complicated in their design because they must provide a proper fuel/air mixture over a wide range of temperatures, engine speeds, throttle settings, and other parameters.

Modern cars put fuel into the air with fuel injection systems, which decide how much fuel is appropriate for each situation using an electronic look-up table. However, a carburetor does this by mechanical parts that change their behavior depending on the conditions.

One behavior in particular that engines have is that when the engine itself is cold, fuel going into the engine tends to condense on the inside of the intake manifold, which means some of it doesn't get to the cylinders. This causes a "lean" running condition (not enough fuel per volume of air) and the engine doesn't run as well. Carburetors typically compensate for this using what's called a "choke". It's a flapper valve at the entrance to the carburetor. When closed, it restricts the air flow going through the main part of the carburetor. It doesn't actuall "block" air from going through, but it does create suction in the middle part of the carburetor so that more fuel is sucked into the air stream.

Here are a few photos of what we're talking about. Here's a few down the throat of a 34PICT-4 carb.

Up on the photo is toward the front of the car, right is to the right. The forward (top of picture) part of the carb is the fuel bowl; it's marked with red dots on this photo. The thing on the right marked by green dots is the part that controls the choke; we'll talk about that in a bit.

This air passage that goes from top top bottom in the carburetor; we're looking down from above.

Closest to us is the choke, shown here completely open; the shaft is marked with blue dots. Farther down the throat is the venturi (green dots), which is a restriction that causes air flow to drop in pressure and suck air out of the fuel nozzle, which is marked with red dots. At the bottom of the carburetor, farthest away from us, is the throttle, which controls how much fuel/air goes into the engine (that's connected to the accelerator pedal). The throttle shaft is marked with yellow dots.

Here's the same view, showing the choke closed.

One question is how is the choke controlled. Well some vehicle/carburetor combinations have a manual choke; there's a control that opens and closes it. You'll see manual chokes on things like chain saws or small gardnen equipment with gas engines, or early carbureted cars. After the 1950s or 60s, most cars had an automatic choke of some sort. It would start with the choke mostly closed, and then open it slowly. The carburetors in air-cooled VW engines used a thermo-electric choke.

Here's the electric choke element from a 34PICT series carburetor

The middle of the choke element is a bi-metallic spring. When cold, the spring holds the choke closed. When the spring heats up, it slowly opens the choke over a period of a bit over two minutes. The spring hooks the end of the choke control arm right where it's marked with a red dot.

The bi-metallic spring in this carburetor doesn't respond directly to the heat of the engine. It's heated by an electric heater element, indicated by the green arrow in the above photo. When you turn the ignition key to "on", battery voltage is delivered to the heater element through the tang on the outside of the choke element (marked by a blue dot). So the thermo-electric choke basically acts as a timer, opening the choke steadily.

Continued Carburetor Work

2012 April 17 09:10

I got a bunch of carburetor work done this weekend. I installed a 34PICT-4 in my vintage Beetle and ran it on Sunday. I realized on Saturday that I'd put in the throttle plate upside-down, so Sunday I fixed that. The carb's not running right, but perhaps good enough to be an on-the-road spare. Later Sunday I spent time deciding if I could resurrect one of the other 34PICT-4s that I have to replace it.

A quick illustration so that people can see what I'm on about. Here are two carburetors, a 34PICT-3 on the right (that's the most common carburetor for the dual-port aircooled engine), and the 34PICT-4 (one-year-only California spec carb) on the left.

You're looking at the left side of each carburetor. The forward part of each carb (to the left in the picture) is the float bowl, where the gasoline sits. The 34PICT-4 on the left has the thermostatic valve circled, and an arrow points to the corresponding point on the right.

Pangur feels about the same way as most mechanics about carburetor work.

Here's the engine running with the 34PICT-4 on Sunday.

You can just barely see the tell-tale brass plug that is the external part of the thermostatic valve.

I've spent a lot of time digging up test equipment to use on my vintage Beetle. It turns out that there's a modern tool that has the tachometer and dwell functions and ALSO is a timing light. It's an Equus 5568 timing light, but it has all the other functions built-in. Here's mine in use:

I'm trying to rehabilitate a couple of the old 34PICT-4 carbs that I've bought. I tried running them through the dishwasher; that cleaned them up a bit, but not dramatically.

The problem with all the carburetor's I've had to some degree is that air leaks into the carburetor around the throttle shaft. This messes up the fuel-air metering and makes the idle unstable and difficult (or impossible) to adjust. The 34PICT-3 that is currently my one good carb has had its bushings replaced. I had the 34PICT-4 that I'm attempting to use re-bushed as well, but perhaps it wasnt' done correctly, or something went wrong.

So what I'm doing now is I'm cleaning up one of the used 34PICT-4 carbs I have and I'm going to see if I can re-bush it myself. Long ago I bought a set of solid brass throttle shaft bushings from someone in England who had some. I'm goin to try installing them into the best 34PICT-4 that I'm cleaning up. Here's a pic of dry-fitting the bushing into the throttle bore.

So hopefully next weekend I'll see how much of a difference I can make with that.

Electric Gyro lives again

2012 April 16 00:09

I bought some Mooney instruments from ebay last fall. They were from a late 1960s model, which is the sort of thing I'm hoping to buy in a few short years.

The turn coordinator in those Mooneys was dual powered; that is, it would work powered by the airplane's instrument vacuum source, OR via electrical power. The motor in the gyro is apparenlty a multi-phase AC motor powered by a DC to AC inverter. In the TC that got, someone had cut the cable from the inverter to the instrument itself.

You can sort of see the back of the TC chassis in the background. That's the valves and plumbing for the "Positive Control" wing leveler system. The post-1965 planes had a system that basically used the TC's sensitivity to bank to kepe the wings level (and thus roughly a constant heading). It was operated by vacuum; thus the hoses coming off the back of the TC to controll the parts of the PC system.

The other half of the system. This takes DC input and creates 3-phase AC to the TC.

So I cut up the cable and spliced each wire together.

Then I tested it by connecting the DC input to the inverter to a test DC power supply. It worked! That was pretty fun.

The Go-Fast Car

2012 April 15 23:37

I'm certainly not unique in having had posters of Lamborghini Countaches on my walls when I was a kid. I'd probably still have at least one around, if I hand't lost a bunch when got some water in our basement in 2005.

The design is frankly kind of crude. It has very little aesthetic sense whatsoever. The body is all flat panels; like the designer started with clay base and then whacked off facets witha matchete. It's a bit like a formula-1 car stretched sideways sot hat it has two seats.

I've had a re-surgence of interest in high-end cars in the last few years, watching Top Gearon BBC TV, where they drive those types of cars all the time. Interestingly, a lot of their take on the Coutach as a car to own is negative. Jeremy Clarkson is the mouth of Top Gear (he's described himself as the "bombastic one" among the hosts. Interestingly, he's written an editorial on why NOT to buy a supercar at all; that it won't improve your love life, and so on, which is very interesting for someone in that business. His article includes this:

This is because, when you are in a supercar, you can resist stabbing the loud pedal for very long periods of time but eventually, you'll think, "Hang on. This bit of road looks appropriate, I'll open the taps." And that's a mistake, because no road is appropriate really for the savagery that results. Quickly, then, you will soil yourself.
There's also a segment of Top Gear in which Jeremy basically lays it out that the Countach "was never a good car" at all.

And I know all that. And I probably wouldn't like driving one anyway. And given that only slightly over 2000 were ever made, and they still sell for not less than $120,000, and insuring one is astronomical, there's no way I'd ever be able to afford one. And yet, I still find them compelling. I bought a couple of books on them recently, because I was buying stuff on Amazon.

The cover picture is the LP500 prototype, of which only one was ever made. It's a fairly photogenic car if you like that sort of thing:

Now many years later, what this book has pictures of that I haven't ever seen is the incredibly integreated drivetrain:

It's technically a "mid-engined" car, which means that the engine is between the transmission and the final drive. I'd alwyas imagined (and drawn) that the transmission had a piece that stuck out to the side and the drive shaft ran back beside the engine. Well that's not the case; the transmission/engine oil pan has a passage at the bottom for the drive shaft to pass through. This means that the transmission/engine/final drive system must be removed from the car as one massive piece, with special jigs, rather than being able to remove and work on one of the three in isolation.

Coming full circle--the REAL reason that the Counatch is part of the furniture of my mind is less because of the car itself, and more than it was in a bad 1980s TV show called Automan. The show was sort of a reversal of (and ripoff of) the ideas of TRON; a computer character comes into the world (and fights crimes and solves mysteries and the usual stuff). In addition to Automan himself, he had a "cursor" that could create physical objects, including vehicles. Vehicles that weren't specifically desguised to make them look "real" were basically physical wire-frame models. The (cursor-created) car that Automan drove was a Lamborghini Countach LP400 with the wire-frame treatment. The car was super-powered, and could make instant 90-degree turns at any speed; a standard gag was to show the interior of the car during these turns, which didn't effect Automan at all but the human occupant got slammed sideways.

ONE working thermostatic valve! Ah ha ha ha!

2012 April 10 02:08

I got some time to work on the new carburetor for my vintage Beetle over the weekend, so that's nice. I cleaned all the small parts that have gasoline in them; there they are set out to dry.

Keep an eye on the thermostatic valve at the top just right of center; we'll be seeing that again.

During the assembly process. Judging by the look on Pangur's face, I'm obviously doin it wrong.

To me, it seems like it actually starts to become a carburetor rather than a collection of parts when the float is in the float bowl:

The reason that I'm assembling a fairly rare 34PICT-4 carburetor rather than the much-more-available 34PICT-3 is that the -4 has thermostatic valve that increasess the amount of gasoline that comes out the accelerator pump when the carburetor body is cold. I'm hoping that makes the car work better when the engine is cold, particularly when the weather is cool out.

For that to happen, the thermostat valve that I install has to actually work. I ended up buying a couple of 34PICT-4 carbs, so I have three thermostatic valves. On Sunday I basically decided that none of them worked. I did some digging on the internet, and e-mailed some people, and posted on forums, and came to the conclusion that all three of the valves I had were broken.

The part that's supposed to move is down inside the valve, but you can get at it with a punch. Figuring I had nothing to lose, I put one of the valves in my bench vice, stuck a flat punch down inside, and hit it with a plastic mallet.

(The arrow points to the thermostatic valve.) No change. I hit it really hard with a plastic mallet; again no improvement. Finally, I hit the punch really hard with a steel claw hammer, and it gave. I was able to break the ball valve free of its seat. So I know have what seems to be a working thermostatic valve. When I get back from my work trip I'll try and assemble the carb to see if it will work.

Turkey cooking times: One VERY Important Factor

2012 April 08 09:52

Cooking times for poultry in the cook book are listed by weight of the bird you're cooking, and they're different depending on whether it's stuffed or unstuffed. It seems, however, that they're missing a very very important factor, possibly the most important one.

I learned to cook Turkey from my mother in law, and I'm not generally much of a cook, so I follow the receipt very closely, so there tends to be very little variation in how I do it. One of the things that I kept having to leave myself notes about is that the cooking times for turkey in the cook book are WRONG. A covered turkey cooks faster than one uncovered, for one thing. We've had Thanksgiving dinner at our house quite a bit since we moved here, and the problem we keep having is that the turkey cooks faster than we expect.

This last Thanksgiving, I read my notes and I realized I'd plan properly, and put the turkey in later so that it arrived at a nice early dinner time. So I did--and it was the longest-cooking turkey ever. It took the better part of 6 hours, which is very long for a 15-pounder. The only significant deviation from normal cooking procedure was I decided to pick up a disposable Aluminum-foil cooking pan from the store when I got the turkey. I assumed that it was insignificant in terms of cooking. Well, we ended up eating well after 7pm, so perhaps it wasn't so insignificant.

I was so annoyed about it that I went out a bought another turkey right after Thanksgiving last year, same brand, almost exactly the same weight, and put it in the freezer. I wanted to try it again with the original roasting pan, to see if it was back to the original cooking speed. We did that dinner yesterday. The same receipe, techniques and procedures as always. Same person doing it, same oven, same temperature, same thermometer. The only difference from last Thanksgiving was we went back to the black roasting pan that we'd always used in the past, with an Al foil cover, as always.

Here are the results. The horizontal axis is time, shifted so that they start roughly at the same time. Vertical is the temperature read in the breast meat by the same thermometer. The green line is the temperature from last Thanksgiving with the oven at 325 F. The red line is Thanksgiving after I turned the oven up to 350. The blue line is yesterday (again with oven at 325). It stops when we turned the oven off because the turkey was getting done too fast.

So just to be clear: green and red line: disposable aluminum foil roasting pan (shiny). Blue line: black roasting pan.

It's nice occasionally nice to be dead right. And the cats got turkey liver, so that's all right.

Why the Bell (Doesn't) Toll: part 1

2012 April 08 09:04

Our doorbell didn't work when we moved in 6 years ago. Thinking back, I think the reason was the doorbell ringer mechanism was inside the furnace air return, so it got clogged with dust. Instead of trying to fix it, I used the existing from doorbell button to a drive relay which turns on a beeper upstairs. That system is great during the day when I'm in my office, but very much not when we're home, particularly we don't hear it when we're watching TV.

I bought a replacement ringer/bell unit, and as shown below, finally installed it. First off, I used painters tape to get everything level and aligned and marked, then drilled a hole into the wall towards the closet to pass the wires:

Interestingly, someone ran wiring up the middle of the cavity, which electrical code really discourages you from doing. There are TWO jacketed feed wires inside the wall, not connected to the verical posts inside the wall.

I did push the wires aside and drilled through the other side of the wall, so I can pull wires up through the closet.

Now before installit it I removed all the painter's tape, leaving the mounting holes and the big hole in the center that will bring the wires in.

Finally the doorbell chassis installed. Hopefully the wiring will be finished soon so that both main doors have a doorbell that people can actually use.

The wiring will take a little time, as I have to join the AC and DC sides of the doorbell circuits together.