Center mount, progressive, 2BBl carb on Type IV doesn't suck FAQ

[trevize1138]

I just finished my final fix to my carb: repositioning the throttle cable linkage to ensure both barrels open 100%. Woo! I actually felt a real difference in how much the bus pulled when I floored it! The thing actually feels a little bit like it's "jumping" ahead when you kick it down completely.

This is great because even before this I wasn't at all dissatisfied with the performance. I could accelerate with normal traffic just fine but I still felt like I was pushing the thing to the limit by doing so. Now it's got that little extra "oomf" to make it that much easier to drive.

Also, an update on the whole auto choke thing. Once I do get it started (somehow I'm flooding it or something now) the auto choke obviously kicks in and the engine revs pretty high for the first minute or so. Not only is the engine getting up to operating temperature quicker but I don't notice any hesitation or flat spotting during the first 5 minutes of driving. In other words, the auto choke is working as designed.
_________________
'72 Ghia Coupe
'72 Westy Hardtop (sold in 2013)
'72 Super Beetle (long dead and gone!)
http://druckenghia.blogspot.com/

[nemobuscaptain]

I would disable the choke altogether. This is the same thing that the 1600cc guys with no heater risers (due to header exhausts) do. Your intake runner is never gonna heat up, obviously since you don't have a preheater tube. You need to tune your engine all the time like your choke is on, and don't need the choke to provide extra richness. It's already setup to run with a cold intake runner.

Not really sure if this applies to your "Solex" progressive. As far as I knew, all progressives for the VW were Weber or Weber knockoffs. Maybe it came from some other VW product????

EDIT: I see that the Solex progressive is rare and was a Weber/Holley competitor. There are some posts on type2.com. You can search there, but I wasn't able to find any tuning posts but I only did a quick glance. I would also maybe look at Hoover's blog. He was a progressive fan, but doesn't think much of the T4 engine. Perhaps there is enough there to help you with any additional tuning issues.

Type2.com also has a few threads about an electric heater sandwich plate that can be scavenged from some GM vehicle or at various ways ways preheater the air or heat the intake runner.

[Randy in Maine]

And here is that link that nemo speaks of....

http://www.type2.com/library/fuel/weber-progressive.html

[Bleyseng]

It will run and in my experience duals or fi is just soo much better. Run what you have now and enjoy it and save up for a set of duals or a fi setup.
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70 Ghia Black convert-9/69 build date-stock w/133k 1600 SP-barn find now with a rebuilt tranny and engine
77 Westy 2.0L w/Ljet, Camper Special engine-95hp and with LSD!(sold)
76 Porsche 914 2.1L L20c, 120hp Djet (sold)
87 Syncro Westy Titan Red 2.1L 2 knob 100k miles

[trevize1138]

[Bleyseng]

[quote="trevize1138"]

[Jake Raby]

The typical trait of progressive lovers and those that think they are effective is the fact that they have never experienced anything else...

It's like a computer, who the hell goes back to dial up after being on DSL?

I crush every progressive I can find, or sell them on Ebay for 5 bucks.
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

[busman78]

As long as there are complete and not burned in a fire, box them up in lots of twenty carbs and I will pay you $5 for each progressive.

Yes I have run Dual and FI, nothing wrong with either of them (reservations about the VW FI system). Aslo played around with other types of carbs that most would never dream of, like big one barrels, which actually perform quite well.

Course the camper special engine (home brew) I am building with your 9550 cam and Len's heads will have a set of Weber duals, so will the 1.8L DTM engine going in a 70 bus.

[Jake Raby]

Cool.. I have a couple right now.. Want them?
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

[busman78]

Yep

[keifernet]

Hey I asked first... LOL

[trevize1138]

Update:

Little by little I've been improving my motor's performance and MPG by figuring out how to tune that mysterious Solex progressive. I believe I just put the last little tweak into things and we'll see how things go from here.

The last little thing I just did was to check the timing, which I haven't done in the 6 months I've owned this bus. It's got that "totally worthless" 009 dizzy but with a full electronic ignition conversion (not just the sensor in the dizzy but coil). I adjusted the timing because after a couple of 30+ mile freeway trips it was dying at idle. I'd only have to turn the mixture screw out just a hair (1/16th to 1/8th of a turn) and the idle would smooth right out again at 850-900.

As this happened 2X I suspected that the timing was being retarded by the spinning of the distributor shaft (happened to my Ghia). I can't verify that's what happened, but the hold-down bolt on the dizzy could have been a lot tighter when I checked it. I made sure it's now good and tight (but not too tight as I've busted a couple dizzy clamps on the Ghia doing that!) I'll find out soon enough if that's tight enough.

So, the timing is now at 7.5* BTDC at idle and 28 BTDC at 3000 RPMs with mixture and speed screws re-adjusted as needed. The result: smooth transition from idle to speed with no flat spots or hesitation in the lower RPMs, strong pull beyond 65mph and last recorded MPG was 18.5!

The MPG is from in-metro driving so about 2/3 freeway and 1/3 stop-and-go city streets. This past fall I got 17.5 MPG going 65 on a 100% highway trip. So, I'm now very hopeful I'll break 20 MPG on a road trip.

That's the psychological barrier for me with this carb setup: if I can get at least 20 MPG on the highway then I'm convinced I don't need FI or duals. Of course, I could still experience other problems people claim such as icing but time will tell on that. I'm not sure if conditions would be ripe right now for icing here in Minneapolis. It's in the mid 50s and sunny but there's a whole lotta snowmelt going on so the humidity is above 50%. I drove about 50 miles today so far and experienced no icing.
_________________
'72 Ghia Coupe
'72 Westy Hardtop (sold in 2013)
'72 Super Beetle (long dead and gone!)
http://druckenghia.blogspot.com/

[Duncwarw]

Maybe Jake Raby will pipe up here about the timing thing?

I got it third hand, but he suggested a different timing to someone on another board and I tried it.

The result, in my case is that the thing is a little less smooth at low revs (Progressive not properly jetted yet) but my head temps are down about FORTY degrees and there's clearly more power at the top end.

If Jake doesn't respond (should be a thread all its own really), I'll try to find the settings again.
_________________
“To find yourself, think for yourself”
Socrates, 470 BC - 399 BC

[trevize1138]

[Jeff Geisen]

...trevize; that's a great tip about cuttin' down a screw driver for the mixture screw. It is still quite awkward, but doable.

I bought a 72 to re-sell, and I replaced the boots and re-built the carb (Weber) Saturday. If one of the boots is loose, I found the runner that it is loose on will drop the corresponding cylinder. Mine had the high idle, and would stall after about 15 seconds idling. My problem is a rotten PB booster hose, 'cause when I plugged the line at the carb plate, it would idle fine, I could reach into the window of the closed door and around the steering wheel, and turn the key, it'll start and idle fine.
_________________
I Corinthians 4: 1 thru 5

‘63 ragtop - ‘68 single cab

[Bleyseng]

[trevize1138]

[trevize1138]

OK, so now that I said the motor's running great and all ... it's now running kinda crappy.

Here's what I think happened just a couple days ago: the fuel pump on my carb ruptured.

Here's why I think that: serious bog/missing/flat spots on initial acceleration at any speed/RPM. The problem gets slightly better after warmup but then it's sort of always there.

So, I'm going to spend some time this weekend, I think, and dismantle that carb and investigate any float bowl/fuel pump problems and then even just give 'er a good cleaning and rebuild. Of course, the tricky part about that is I don't have a rebuild kit for this very rare carb and therefore I don't have a replacement fuel pump diaphragm if the one in there right now is ruptured.

If I can't figure out a solution to that then I doubt I could find a rebuild kit for this carb and the only real solution would be, you guessed it, a different carb! I know the progressive setup works just great, but I just may find myself deciding to bite the bullet and get duals if that's the case. I hope it won't come to that, though, because that would mean I'm wrong and the guys promoting duals/FI are right.

And that just can't happen!
_________________
'72 Ghia Coupe
'72 Westy Hardtop (sold in 2013)
'72 Super Beetle (long dead and gone!)
http://druckenghia.blogspot.com/

[busman78]

Bleyseng, pop over to the aircooled technology forums and read the blurb I put in the radio show on FI.

FI is wonderful, my new Ranger has it and it is smooth. Personally I do not want to travel the hi-ways, by-ways and back roads carrying a box of spare parts and test equipment so when the thirty year old FI system decides to leave me stranded out in the land of nowhere. Carb systems are as old as cars are, but the carbs I am using are newer than the "thirty year old VW FI" and as Jake said, if you got DSL would you go back to dial-up? Of course not. So why try and run a system that was built during the time of Telex/PBX. VW's FI system was problematic and had constraints even when it was new, at least a carb system will not and never has left me with monsterous tow bills.

[busman78]

Trevize1138, Also check your accelerator arm to cam. The cam arm that initializes the accelerator needs to be adjusted so that it does not touch the arm of the accerator pump but will as soon as the pedal is stomped. A gap there will give you a big time bog on acceleration.

How many turns is the idle mixture screw out? Anything more than three and the idle jets are too small and you are drawing fuel by vacuum through the metering circuit and this to will also cause a bog.

If the carb checks out okay take a look at bumping the timing up another degree (or two). Watch the advancement with a timing light as you slowing bring the rpm's up, your looking for bouncy advancement. If you are at an rpm that the 009 is fluctuating, acceleration will bog until the advancement catches up.

The above also happen with duals, so the cure is not always switching to duals. Oh, by the way I have nothing against duals.