TheSamba.com :: View topic - Centermount, progressive, 2BBl carb on Type IV doesn't suck

Sat Feb 24, 2007 10:15 am

You read right. Now, I don't know as much about engines, carbs and all that but I do understand the basic reasoning behind why my particular setup shouldn't work so well:

* No manifold heat
* No intake air preheater tube
* Dual carbs are always better than single

While that's all true it's undeniable that my engine runs great with a center-mounted, 2bbl, progressive Solex (yeah, you read right, it's not a Webber) carburetor. And, you know what else? The dizzy is a 009.

Granted, the dizzy's been outfitted with electronic ignition and I know that really helps but the 009 without the vac advance is also supposed to "suck." Somehow, it doesn't.

Now, that's not to say that it couldn't be better: flat spots during the first 5 minutes of driving and MPG not quite where it could be. But, it's a far cry from being a "non-option" as I've often seen people state about this setup.

Yes, it would be nice to have better torque when the motor is cold and 2-3mpg better. But, considering how well it starts, runs and the relative ease of adjusting a single carb vs. dual it seems a good tradeoff.

I now open the floor to wild debates. :)

Sat Feb 24, 2007 10:23 am

trevize1138 wrote:

Now, that's not to say that it couldn't be better: flat spots during the first 5 minutes of driving and MPG not quite where it could be. .

Yes, it would be nice to have better torque when the motor is cold and 2-3mpg better.
I now open the floor to wild debates. :)

I would try a stock dizzy in the bus with the electronic ignition for you to compare...I think you will like the results as in "no flat spot".
The long steel runners with a single carb make nice low end torque but the cold starting problems cuz of fuel condensation on the inside of the runners kills drivability. Duals just run better when setup right.

Me, I prefer FI.

Sat Feb 24, 2007 10:42 am

Bleyseng wrote:
I would try a stock dizzy in the bus with the electronic ignition for you to compare...I think you will like the results as in "no flat spot".
The long steel runners with a single carb make nice low end torque but the cold starting problems cuz of fuel condensation on the inside of the runners kills drivability. Duals just run better when setup right.

Me, I prefer FI.

I have been thinking about getting an SVDA dizzy to improve flat spots.

Interesting: "long steel runners with a single carb make nice low end torque" that sounds like a positive about the single carb setup! Yes, I deal with the icing issue when I first start it up. But, the worst of it is over in 10-15 seconds. The next 5 minutes after that I just have to be more assertive on the throttle. After that it's smooth as butter. A vac-advance dizzy would only make that better.

I wanted to start this topic to specifically have people discuss this issue of the single, centermounted carb on the Type IV. It seems to always illicit some empassioned points of view. I'm just curious to learn as much as I can about this and hopefully help everyone else gain a better understanding of it.

When you search on the subject you also find quite a few people out there who have a similar experience as me: single, progressive carb and they're happy with it. Then you get the opposite side of the story with people saying it's the worst thing you can do. They can't both be right. :)

Sat Feb 24, 2007 11:40 am

Having run progressive carbs for 18+ years on a Type 4 I think both crowds can be right. A lot of progressives run like crap, but they can also be made to run quite well. If you look at the progressive carb kits sold for Type 4's on eBay you will find that they come with a non descript rebuilt carb. What are these carbs tuned for? More likely a Jeep, or a Vega than a Type 4. Are they a Holley, a Weber, a Solex, or a Motorcraft? I have had a dozen that I have taken off some engine over the years and none of them were quite the same as another if even close.

Typically the throttle linkage hook ups were undependable if not down right dangerous to use, and half lacked a working choke. Jetting is all over the place.

If you just go TO a junk yard, find a look-a-like Weber progressive, take it home, rebuild it, and then bolt it on untuned you can't expect it to run well, yet this is just what these kits do. Pick a random carb out of a bunch culled from a wrecking yard and slap it on. If you take a carb that is tuned for a V6 in a light car with a six inch runner length and try and use it on a 4 cylinder pushing a loaded bread box and with 14 inch unheated runners to boot, you can't expect much.

I would like to see a "Progressive Sticky" where all negative rants and even unhelpful "filler" post were removed, so that people who run progressives, and there are many of us, can share ideas without being pounded, or wasting all our time searching through the chaff. Actually a forum of our own would be even better as we could have multiple threads.

I am determined on my next van to take hot exhaust gasses from the air injection ports on a 1800 head and use it for manifold heat on a progressive. I want to go with at least a Camper Special equivalent engine if not a Power Stroke and run plenty of compression. I am shooting for 30mpg and will not tolerate any flat spots or sputtering. Dropped valves are not an option.

Sat Feb 24, 2007 11:52 am

Thanks for posting, Wildthings!

Yeah, a "Progressive Sticky" would be nice here.

I mean, let's face reality:

A - Lots of people out there have busses with progressives.
B - The majority of them are not going to totally swap-out their current setup for dual carb or FI. They just aren't. Get over it.

Therefore, it would help a LOT of people to know more about how to get a progressive setup to run well. It's not as simple as "Dual and FI are better." While that's true it's often a moot point. I mean, we are all old VW bus owners. Typically that means many of us are strapped for cash. It's better for most of us to fix what we've got rather than just throw money at the problem ($15 for a rebuild kit or new jets vs. a few hundred bucks for a whole new setup.)

Anybody have some good links with data on setting up, jetting and running progressive carbs on a type IV?

Sat Feb 24, 2007 1:07 pm

Quote: While that's all true it's undeniable that my engine runs great with a center-mounted, 2bbl, progressive Solex (yeah, you read right, it's not a Webber) carburetor. And, you know what else? The dizzy is a 009.

Call us back when you start getting some humidity up there in Minnesota. It's not so much the cold as the confluence of cooler temps and humidity that cause icing. In the south, with their high humidity, icing can occur into the 70s. BTDT.

And disconnect your choke. Your runner never heats up so you will have to tune the carb itself be rich enough to overcome the cold intake all the time.

Quote: Yes, I deal with the icing issue when I first start it up. But, the worst of it is over in 10-15 seconds.

That's not icing.

Sat Feb 24, 2007 2:10 pm

I fought a single webber in my 72 for 4 years. Just a headache with the icing on the steel runners and poor mpg. When it was warmed up after 20 minutes it ran great but it was a pain until then, leaving by the side of the road with frozen runners many a day. I mean it just stopped running when I neede to get to work on time so I ran some piping to steal some warm air up around them and everything.

Too much trouble to reinvent the wheel when you can have duals that work great.

I still perfer FI as its just get in and go plus with the CS I mean I really go!

Sat Feb 24, 2007 3:39 pm

Been running progressive carbs for 16 years now. Also set up a lot of duals (nothing against them). Of all the progressives carbs I have obtained on the secondary market or off engine cores, there has been a lot of them, only one was actually been set up correctly. I feel the numer one failure which feeds the anti-progressive carb advocates is they never realized or fully understood that a progressive carb has two Main Jets, two Air Correction Jets, two Emulsion Tubes and two Idle Jets and they must be configured to work harmoniously. Never have I gotten a progressive that had the accelerator pump arm correctly set from the factory and it is the primary cause of off idle stumble. Out of the box, direct from the best Weber distributor in the nation will only get you started. Every engine is different, then take into account altitude and what works on your engine will not work on mine.

I support a sticky for Progressive carbs minus the nay-sayers.

Sat Feb 24, 2007 4:21 pm

The introduction of heated air helps with both icing and mileage.

Sat Feb 24, 2007 7:55 pm

This was a pretty good prior discusssion. Perhaps consider reviving it?
http://www.thesamba.com/vw/forum/viewtopic.php?t=180520&highlight=weber+progressive

Sat Feb 24, 2007 8:36 pm

I ran a weber progressive on my 74 and I never had any problems with it at all. I ran it through Baltimore hot summers and extremely cold winters and through the blueridge mountains with great success. My father in law has one on his 76 now and also has had great luck with it. I can say however owning both fuel injected, dual carb and single carb busses that when a dual carb setup is run with a mallory unilite or even better a fuel injection setup is run the improvment is drastic, you wont belive all the power you were being deprived of, and the gas you will save. In the long run the weber progressives will give the engine a shorter life due to generally running lean. Depending on the age of your rebuild I would leave the progressive and drive it like it owes you until it is time for a rebuild. Then I would do dual dellorto's and a mallory distributor. Or even better run a stock l-jet fuel injection system or a retrofit kit.

Sun Feb 25, 2007 9:18 am

I'm in upstate NY (temp extremes AND humidity) and I have a 2L with the progressive. I have yet to re-jet and have NEVER experienced some of what I read.

At 15F in the snow after three days of not being started I fired it right up and drove fine. When it's REALLY cold, the idle suffers and I can get a 009-like flat spot but nothing like the horror stories posted by others.

Here here Wildthings. Helpful and positive tech postings on the Progressive should have been a sticky long ago.

As in all other subjects, attacks from the inexperienced or uninformed are at best trash to wade through and at worst convincing to newbies.

Mon Feb 26, 2007 6:29 am

I was waiting for your post, Duncwarw. :) You seem to be the most vocal advocate of progressive carbs and a real example of why they, indeed, don't suck.

I'd still like to know if anybody has good information on how to jet and otherwise tune progressives for busses. I think I remember seeing some formula somewhere for the size of jets you need depending on displacement but that was for 34 PICT-3 carbs, not progressives.

Mon Feb 26, 2007 7:46 am

I have a 74 Panel w an 1800cc.I've had a typeIV kit weber prog. w va dis for 4 yrs. Yea it takes a little longer to warm up in the winter,but a good trade off for lo maint. Runs good once warmed up w smooth throttle responce. I do tweak the air-fuel mix at the change of seasons 1 full turn. Lean in the winter,rich in the summer.
I also have a 77 Sunroof w a 2ltr. non hyd. I'm running duel weber 40s w hex linkage and an older GERMAN .009 it does have a flat spot gets poor gas mi.(15-18mi.) but I can suprise folks on the fwy. if I need to pass. I don't jack with them at all I'll let a pro mess w them and set them a little rich.At the moment I could use a set of the nylon bushings for the hex link. but it's ok for now the play is so minor.

Mon Feb 26, 2007 7:53 am

Thank you. I'm well aware that the progressive may be less than ideal but I'm also a pauper. If the Del Orto's I bought years ago weren't seized up, I'd probably use them.

There seem to be a lot of people out there with the single Weber (or variants thereof) and I personally feel that posts like "it will never work" and "those carbs suck" do not inspire confidence. Most of the negative posters are likely getting their info second or third hand from somebody who actually had a Progressive and didn't know enough about setting it up.

I'm almost certain "Wildthings" and maybe Nigel Skeet posted really good info on jetting and pre-heating. "Fido" is a wealth of information on jetting as well. Hopefully, the mods will gather that info together in an "FAQ".

Also, I read an article on aircooled.net about it some time ago.

Mon Feb 26, 2007 8:53 am

Here is a thread that list several peoples jetting.

http://shoptalkforums.com/viewtopic.php?t=86620&highlight=progressive

Mon Feb 26, 2007 12:00 pm

I've had a question ever since getting my bus this fall just about how to adjust the idle on the damn thing. As I said at the top of this thread I've got some kind of Solex progressive carb and I've found diddly SQUAT on the net for info on it.

Someone did PM me on the subject and recommended I just have a local VW mechanic look at it. Well, shy of doing that and considering I did successfully rebuild the 34 PICT-3 on my Ghia last winter I just went out and removed the damn carb to get a closer look at it.

1 - It seems pretty obvious that the PO attempted to correct what was perhaps a bad idle by cranking the automatic choke nice and tight. I've been getting about 14-15mpg in town and 17-18 on one road trip going 65 (it was right around freezing) So I'd guess those numbers would improve just by setting that stupid auto choke right. =)

2 - Although the auto choke was too tight the throttle arm poition screw that rests on the cam was backed off so much that the main throttle wasn't any more open than it should be at idle.

3 - If this Solex carb is anything like the Webber progressive then I believe I've finally located the idle mixture screw: http://store.cip1.com/Merchant2/graphics/00000001/XXX-WEBER-32-36DFEV.pdf. On mine it's recessed pretty deep at the bottom, front, right corner of the carb body, which seems about the same spot as is on the Webber. It was originally turned only 1/2 a turn out from bottom and I've reset that to 2 1/2 turns.

4 - If, again, it's anything like the Webber, then the actual idle speed screw faces the freakin' front of the bus, so that would make it an absolute bee-yatch to adjust while on the engine. But, I've got an angled screwdriver so it's at least possible. Also, can someone confirm that the "idle speed screw" on the webber from the PDF above seems to just directly adjust how open the throttle plate is in the main carb throat? I know my 34 PICT-3 is different and there's an idle speed screw and a mixture screw that have nothing to do with the throttle plate. It looks like this carb is set up similar to older PICT carbs in that the actual idle speed is adjusted by opening/closing the throttle plate.

Mon Feb 26, 2007 1:24 pm

The carb can be mounted either way, just flip the lever arm, really comes down to where you have your cable coming through the firewall. Take a stubby medium blade screwdriver and saw off half the handle, file of sand the edges smooth and you will have a perfect idle adjuster for the idle screw in the front. The one I made has less that 1" of blade and 3/4" of handle.

Mon Feb 26, 2007 1:57 pm

busman78 wrote: The carb can be mounted either way, just flip the lever arm, really comes down to where you have your cable coming through the firewall. Take a stubby medium blade screwdriver and saw off half the handle, file of sand the edges smooth and you will have a perfect idle adjuster for the idle screw in the front. The one I made has less that 1" of blade and 3/4" of handle.

Turns out I've got the perfect stubby screwdriver for getting at that idle speed screw. Woot! If I flipped the carb the cable would be on the wrong side, so I'll just deal with the bass ackwards idle speed screw for now unless I come up with a solution for the cable.

I put it all back together again but I think I've flooded things a bit after wrestling around and pumping the fuel pump a couple times to get at one of the front mounting screws. It started up right away when I did the hole push the pedal in slow, release and start and ran at high idle for 5 seconds before dying. Then it just didn't want to start up again. Oh well.

I'll wait to try starting it again for when my wife gets home with the Subaru and start it while hooked up via jumper cables. The battery was running a tish low after cranking it several times.

Mon Feb 26, 2007 7:04 pm

I have a weber progressive and it is working a treat at the moment (summer in Aus!).:lol: To improve warmup I got an air cleaner off a 1970's Mazda (IIRC) to pipe warm air in from the standard pickup on the right side head. It is mounted on an adaptor from aircooled.net. I choose that air cleaner because the flap that controls the hot air is closed by a wax capsule thermostat whereas most use vacuum to drive the flap.

The other advantage of using the "traditional style" single carb air cleaner is that you can pipe cold air in from over the battery when the flap has activated. Those tiny "sports filters" on progressives give you the worst of both worlds, sucking cold air at start up and warm air the rest of the time!

Fortunately a cold day here is 10C (50F) but this is still enough to bring out the dreaded progressive flat spot. Hopefully the air cleaner will help... :roll: