With Wings As Eagles: Car/Mechanical Entries

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.


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.


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.


Bad To The Bone: instrument panels come full circle

2012 April 06 09:53

My wife and I took a short weekend vacation over the winter to the Sevierville, Pigeon Forge, Gatlinburg area of Tennessee. While we were there, we visited the Hollywood Star Cars Museum in Gatlinburg. It has some interesting cars from movies or owned by movie stars. It also has some other interesting artifacts, like the Batcomputer from the 1960s Batman series:

They have a neat array of props from James Bond movies, including a Golden Gun prop from "The Man With The Golden Gun":

Among its vehicles, it has one of the motorcycles used in "Terminator 2". It's a 1990 Harley Davidson Fatboy. I took this image of the overall bike:

And then one quick shot of the instrument panel

Because my wife really isn't into car museums.

I late found myself looking at the second photo a lot on my phone, looking at the speedometer and light panel:

The bottom of the panel, just below the key switch, are very clearly warning and function lights. The red light in the lower rightis probably the oil pressure warning light. The green one in the center bottom is probably the "neutral" indicator light. The lower left blue one is probably the high-beam headlight indicator. But are the other colored things in the next row up lights, or just trim?

It took me a while to figure out why this one photo of this motorcycle was obsessing me so (meaning a couple of hours for an evening googling photos trying to find better depictions). My revelation was--I'm obsessed with instrument panels of vehicles. I'm not sure why this was a revelation. Whenever I got on a trip I take pictures of my own instrument panel, or particularly of the rental car I'm driving. One of the things that facinates me about my vintage Beetle is the extremely austere instruments: one speedometer dial, which an embedded fuel gauge, and two warning lights. When I look at an airplane for sale, I want to look at the instrument panel more than pictures of the outside of the airplane.

I found an few interesting depictions with Google image searches: an article on howstuffworks.com on the Harley Fatboy, and another specifically on the "grey ghost" on harley-fatboys.com.

Then I started doing some searches on YouTube, and ran into some interesting stuff. Here's a couple of videos featuring someone starting and running a Fatboy where you can see the instrument lights when they turn on the ignition: here and here.

After I ran into those examples, I did some more thorough searching for images, sometimes including for-sale sites. Here's a for-sale ad for a 1992 Harley Fatboy in Tennessee. If you click on the "more photos" link, the middle photo has a nice view of the speedometer/instrument cluster in bright light.

I found a very nice image of the tank and speedo by Carl Johan on flickr:

I found some other photos on flickr, including this one by Stacey Warnke, which I think is the very same motorcycle. The other photos near it in her photostream are of other cars in that same museum. The image shows the odometer milage of 727 miles, and the page says the photo was taken on July 31, 2008. The odometer in my photo, taken January 2012, lists has 732 miles: