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Wed Feb 10, 2010 5:49 pm

I have both and am wondering which I should go with. I am going to have Keith work his magic on a 34pict3 for my bus and am trying to figure out which to use. I know the DVDA came stock (which is a plus for me) but might not be nescessary. I have always used SVDAs but have this opportunity so I thought I would see what you all think.

Also, does anyone have the table listing the flange #s for different carbs and what they came with? I have seen it around but I guess I didn't bookmark it.

(P.S., I searched and read but didn't find much for pros and cons so don't tell me to go search :P )

Wed Feb 10, 2010 5:52 pm

The second vacuum is a retard and all it does is lower the emissions.

Wed Feb 10, 2010 5:54 pm

if you have stock dual carbs the retard is desirable because the engine will idle on the central idle circuit better with the retarded timing. once you get off idle all the retard goes away and it's no different than having a single vacuum advance distributor.

Wed Feb 10, 2010 6:01 pm

I had a 1971 for close to 350,000 miles and used a DVDA for about 280,000 of that. It worked perfectly well and there were no flat spots or gremlins. IMHO I would use an original for your bus if you can find one for three reasons:

1. It keeps the bus closer to stock and as cars age their value is higher stock than otherwise. Let the new buyer change it if they want when that time comes.
2. There is a long shot chance that the global warming and smog laws will merge as far back as the late 1960's. If this happens then there will be a shortage of the correct smog parts. While I live in California, I saw something last Thursday none of us around here had ever seen before. It was a mobile smog inspection on the side of the road where the state was pulling over cars to check them. If something like that caught on nationwide, owners who aren't stock would wish they are.
3. There is no value in performance gained by changing to a SDVA or an 009 with the carb you have.

Wed Feb 10, 2010 6:08 pm

I agree with Scott, the idle is nice, you sure notice the increase in flow out the tailpipe when the retard kicks in, never considered the inreased flow as being better for atomization/distribution but it makes sense. The response off idle is great with a DVDA too.

It's your bus, but if I had the correct parts I'd run them, sure makes passing smog easy around here and who knows how green WA is going to get in the future.

Wed Feb 10, 2010 6:30 pm

calebmelvin wrote:
Also, does anyone have the table listing the flange #s for different carbs and what they came with? I have seen it around but I guess I didn't bookmark it.

It is up here....

http://www.thesamba.com/vw/forum/viewtopic.php?t=185095

Wed Feb 10, 2010 7:33 pm

Randy in Maine wrote: calebmelvin wrote:
Also, does anyone have the table listing the flange #s for different carbs and what they came with? I have seen it around but I guess I didn't bookmark it.

It is up here....

http://www.thesamba.com/vw/forum/viewtopic.php?t=185095

Thanks for pointing me in this direction. One question, I have a 205 Q distributor but it is not listed here. I assume that is because this table is for the beetle. Anyone seen one for buses?

Wed Feb 10, 2010 7:45 pm

Thanks everyone for chiming in. I do consider myself leaning more towards stock for my buses and will probably use the DVDA, I just wanted to see if there was an advantage (or disadvantage) to doing either.

Another question I have is how everyone feels about the altitude compensator setup. I know it has been thrown out on most buses because it is viewed as useless but I think they must have put it in for some reason. Is it just to over the top to want to hook it back up?

busdaddy, your '71 is what I aspire to have in mine. This is beautiful.

Wed Feb 10, 2010 7:54 pm

Just found this in my search for the 205Q. Look right?

Kelley wrote: Glutamodo wrote: VW 327-1/2 34PICT-3211905205Q? BUS1600DP, 1971 125 60z dual USA g57,5 pilot jet

From Andy's complete list, he was kind enough to send me a copy. I believe that the stock distributor was a dual vac canister.

Also:

kjspgd wrote:
Here's what was stock for my Bus (71 DP Manual) called for:
Flange 280-1- Calling for 125 60z 57.5 211905205Q
Flange 327-1/2 Calling for 125 60z 57.5 211905205Q?

Wed Feb 10, 2010 8:45 pm

we had the altitude compensator. If I remember it helps control the return to idle when you lift off so the bus doesn't stall. I would try to find all good parts as cheaply as you can and install them as they become available. If you find a lot that are bad then buy a spare as you can in case yours fails 10 years in the future. I know that the one on my 1971 was still quite good at 350,000 miles.

Thu Feb 11, 2010 12:45 am

The altitude compensator also opens the carb slightly when decelerating, say, when coming down a hill. This keeps a burnable mixture going into the engine. Without it, you tend to get 'popping' in the exhaust.

Thu Feb 11, 2010 11:38 am

Here is Andy's more complete table of carbs in a Word document, which does include bus and ghia carbs: http://members.trainorders.com/android/temp/CarbBaseFlangeNumbersA.doc

He originally posted the link to it here: http://www.thesamba.com/vw/forum/viewtopic.php?t=365762&start=20

Thu Feb 11, 2010 11:49 am

Awesome! Thanks a ton. Now I just need to check my flange #s and see what I have.

Thu Feb 11, 2010 12:54 pm

pretty simple really.
if the carb has a port for retard then it's a DVDA carb. if it doesn't then it's a SVDA carb.

Thu Feb 11, 2010 2:08 pm

telford dorr wrote: The altitude compensator also opens the carb slightly when decelerating, say, when coming down a hill. This keeps a burnable mixture going into the engine. Without it, you tend to get 'popping' in the exhaust.

Huh, I was wondering why it was doing that. Guess I should put that on my list as well!

Thu Feb 11, 2010 3:12 pm

skid wrote: telford dorr wrote: The altitude compensator also opens the carb slightly when decelerating, say, when coming down a hill. This keeps a burnable mixture going into the engine. Without it, you tend to get 'popping' in the exhaust.

Huh, I was wondering why it was doing that. Guess I should put that on my list as well!

But you can also get "popping" in the exhaust on decelleration if you have any exhaust leaks so make sure you system is tight. With these vehicles being as old as they are I have seen way more not running the original throttle positioner/ alt compensator devices than I have with the stock stuff intact and working. If it's there and working great, if not I've never seen it be a big issue... if your not "emissions tested/bound state" that is.

Thu Feb 11, 2010 4:07 pm

keifernet wrote: skid wrote: telford dorr wrote: The altitude compensator also opens the carb slightly when decelerating, say, when coming down a hill. This keeps a burnable mixture going into the engine. Without it, you tend to get 'popping' in the exhaust.

Huh, I was wondering why it was doing that. Guess I should put that on my list as well!

But you can also get "popping" in the exhaust on decelleration if you have any exhaust leaks so make sure you system is tight. With these vehicles being as old as they are I have seen way more not running the original throttle positioner/ alt compensator devices than I have with the stock stuff intact and working. If it's there and working great, if not I've never seen it be a big issue... if your not "emissions tested/bound state" that is.

That's true, I momentarily forgot about my exhaust leak...haha ;)

Thu Feb 11, 2010 4:35 pm

It only takes a small leak at any point on the exhaust system to get the "popping on decel" going. Type 1 engines are famous for the "donuts" or the heat exchanger pipes to donut's to exhaust for leaks and or if the shitty fiber gaskets that come with most aftermarket exhaust systems are used instead of the factory style metal/asbestos, fiber/metal sandwich style are used at the heads.

type 4 engines can have leaks at the heads/copper washers on all but the 79-'square port" rarely have a leak there. But every other point in any exhaust system can and should be checked for leaks for more reasons than just popping on decel... in other words it's dangerous in more ways with CO ect and effects on the engine over all.

Thu Feb 11, 2010 5:23 pm

hot (no pun intended) tip.

The donuts get loose and allow that pffffst sound where the stock muffler or headers connect to the heat exchanger. Eventually the vibration wears the heat exchanger pipe and the donut so the pffffst sound grows into a pup pup pup sound.

Back in the 1980's I experiemented with new exchangers, factory muffler, five or six different muffler pipe sealants and none worked. Then the red high heat silicone came out and I tried that, (There is also the copper ultra heat stuff now. With the red high heat stuff I could seal up leaks and as long as you let it cure over night first, it would last until you removed the clamps. Just be sure to wire brush the metal pieces first to clean them up a little. Get the silcone between the donut and exchanger pipe by putting the silcone on first and sliding the donut into it.