Carburator

[78 Busdriver]

Is there an alternative single carb for a bus other than the 32/36 progressive carb?

[NoBudgetVWGarage]

Don't believe so.
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1969 Transporter
1968 Ghia
1959 Ghia Hot VW Drag Car

[Xevin]

[SGKent]

many can be adapted, Back in the 1970's bug owners, especially in SoCal wanted more power so Holley released their version of the Weber progressive as a kit to boost power. Over the years many other folks bolted progressive carbs on. The problems on a single port bug or single port bus are little because the manifold is heated. When they were adapted to late T4 bays the problems began because there are 4 runners and they are unheated. Regardless of the single carb used on a T4 you will still have to deal with the 4-runner uneven distribution of fuel issue, and the problems with carb icing and fuel puddling in a cold runner.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

Easy to take the center manifold section for the progressive and make an adapter to bolt on any carb you want. Have thought about bolting on a 34pict3 just to see how it would work. FYI, some of the T127 engines came with 32PICT1 Solexes IIRC. Even a 30PICT* will pass almost the same air as a 34PICT3.

The Weber/Holley can be made to work very well on these rigs. Eliminating the power valve or changing its vacuum source to ported vacuum and then rejetting can make these carbs run quite well. Also eliminating the high speed enrichment on the secondary barrel and then rejetting will improve on the secondary side.

IMO, the four runner argument is BS. I thought that at one time decades back myself and made a two runner system copied after the dual port Type 1 setup. Made no change in how the carb worked at all, whereas eliminating the power valve or altering its vacuum source makes a big change.

[78 Busdriver]

I have a single carb right now, I just want a little more get up and go. The 2 other buses I've had have been fuel injected and they got up And went good.

[78 Busdriver]

So wildthings your saying in screw the power valve and remove it and re jet and it should be better? I do have vacuum line going from the distributor to the carb

[Wildthings]

[SGKent]

So Mike - call it what you want but the air to fuel ratio does vary between the front and rear runners when using a progressive because of the placement of the runners to the primary and secondary venturi. The fuel is not equally distributed between front and rear runners - please don't tell others that is BS. I have no idea how we went from "what carbs fit" to an argument that buses will run with progressives. I never said they wouldn't, in fact my mail box is full of e-mail exchanges with others here helping them tune their progressives to run right. But even then there will never be an equal A/F balance between the cylinders, and icing will always be a threat. That may be acceptable to some here, to some it may not be but it is an individual choice.

If you want, go to equal size venture and put in a gear, lever or cam to open both venturi at the same time so the A/F ratios are more even but then it can't be called a progressive anymore. It is progressive because one venturi is drawing fuel at low speed and the other opens when the need is higher. Fuel is generally drawn by the runners closest to the venturi unless you build a taller manifold. Sometimes fuel is slung outwards - that is how science works, not a creation of BS or old wives stories. Look at a river sometime and notice the eddies and whorls, some even flow backwards. The faster currents flow to one side. Air and fuel in a manifold are likewise, and that is why cars went to fuel injection. It is easier to control the mixture at each cylinder at the speeds these engines work at. Issues like vapor lock go away. Icing problems generally go away.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

I might agree with you on the earliest fairly crude manifolds that were sold for these engines, but the later manifolds are going to flow fairly evenly from cylinder to cylinder. These manifolds are certainly no worse in this regard than a typical street V8 manifold with a staged carb and a whole lot better than a lot of straight four and straight six manifolds with any single carb.

The problem with these carbs lays elsewhere and is tunable with some understanding of how the carb works.

[SGKent]

I never said that they weren't tuneable. What I said was that the mixture is never going to be equal and icing is always going to be a risk unless heat is added. Someone sticks one on because they get told it is a solution to FI not running right. Maybe their injector seals are bad - $10 worth a parts and 1/2 hour of time to replace them, instead they get sold a $350 carb kit then spend the next six months trying to get it to run right. My mailbox is full of people who have gone thru this, and in each case I've walked each one as far as they can go to making their buses run right. Overcoming cylinder mixture differences and icing I can't help them with using a standard progressive. Spent a lot of years racing with them, know their limitations pretty well. They will run as well as any single carb on a T4 bus but not as well as FI, duals or non-progressive equal venture carbs (basically an equal venturi carb set up to open both almost at the same time). Progressives work quite well on T1 engines.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[busman78]

Those that say something will not work because of science or theory have actually never done it.

Below some pictures of a T127 with Weber 32/36 DFV on a 2L, the adapter will also accept a Weber 38/38 DGS, a Holley 350 cfm. Never got around to running the exhaust tubes to this set up, the hot air feed into the air cleaner did the trick. The DGS on you four tube will provide more humph.

Now the Solex 32 carb that comes on the industrial engine does not have a acceleration circuit, doesn't need it since they usually run at a consistent rpm. The Solex 34 PICT 3 bolts right on albeit a crappy carb, it will run a 2L engine but needs the venturi opened up and some jet work. What does work is the Weber 34 ICH, same as a ICT but has an enrichment circuit and lots of jets to play with. On my 2L it pushed the limits of the carb since the engine had large valve heads, 8.5:1 and a CB cam, but it worked.

[SGKent]

Edit - Busman78 we were posting at the same time. Yes a setup like that would work. Beware of pulling heated air in all the time. I had a Jeep engine catch fire on a long grade because the high air draw and heat ignited the coating on the aluminum tubing and in turn it turned the carb into a blowtorch that partially melted the inside of the manifold. A heated setup like that would be easier to keep tuned than duals and offer better off idle performance.

my original post:
probably one solution would be to build a custom runner where two went to four. Each side would have one runner most of the way they bifurcate to two runners. This would equalize fuel between all 4. Heat is another issue but it would be easier to heat two runners than four.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[busman78]

Yea, would not need that heat hose to the air cleaner in the summer, although the exhaust heating the manifold really should be hooked up for unleaded fuel likes to be warmer than the old leaded stuff.

[SGKent]

[busman78]

I do recall back in the old days the cloth corrugated hose on water pumpers for it attached to an adapter that was in direct contact with the exhaust manifold and that adapter would glow.

Basically the set up I have there is similar to what the T1 did in the early 70's, capture some of the residual hot air from the cylinder/push rod tube area, not scorching hot, but warm enough to keep the frost off the outside and the mixture comfy.

[SGKent]

I think exiting air off the cylinders would not be an issue other than maybe getting things a tad too hot once and awhile, but you could use an infared gun on the ducting and carb body etc after driving hard to come up with a mix that worked well. The CJ7 pulled air off the ex manifold area.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[mike77777]

hello all, I have the weber carb setup on the bus I own, came with it when purchased 10 years ago. Aluminum carb mounting block, two steel tubes left and right feeding the intake ports on the head. 2.0 liter i977. I took an old license plate, and have it fastened to the top of the intake runners to prevent icing. it is folded over the sharp bend near the heads in an effort to trap some heat. Previous owner had 2 bread pans , one on each side fastened. I had this one on the road for about 6 years in a row, the setup worked. nothing to compare it to, but it is simple to adjust, or change carb jets. Simple linkage for the auto trans, threaded rod to the carb from the lever on the trans where the throttle cable connects, snaps on a ball on the carburetor. A good strong accelerator pump squirt seemed to help when I had her running. Had her parked for a while, and am just since August cleaning and performing necessary repairs/upgrades. Alternator, oil cooler, clean heat exchangers, clean all engine tin, new fuel lines and full tune up parts. rear main seal, and torque converter seal renewed while engine was out.

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patience and putty

[mike77777]

will get some pics of the carb setup on here, engine is back in and hooked up. Fixing electrics this week, inspect, clean/replace the 40 year old wiring. Ground and positive battery cables were replaced with new at the start. Quality Battery was installed also. Thank you for your insight on the single progressive carburetor pros and cons. mike
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patience and putty

[orwell84]

I am interested in learning more about the power valve mod for the Weber progressive. One mod seems to involve blocking the vacuum passage which drives the power valve. The other, which involves routing a steel vacuum line from the vacuum port to the power valve I don't really understand.

Since I will need this vacuum port for the vac can on my distributor, I think blocking the vacuum passage to the power valve would be my best option, though I am still a little fuzzy on the details.

I am experiencing the off idle stumble common to this carb. It happens sometimes moving from a dead stop and if rpms go way down like when slowing down to make a turn. I have never had issues with icing and since I mostly do highway driving, a little throttle feathering doesn't bother me much. I only bought this carb to keep me rolling while getting my originals rebuilt, but I like its simplicity and reliability.

I would very much appreciate a more detailed explanation of the power valve mods, especially as how it could best be done when using a dual advance distributor.

Thanks!