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

[mikedjames]

[THE KESZTHELY KID]

Thanks Mike,

The thought of single Carb' simplicity is tempting but you have a made a valid point
FWIW My first T3 was a 1983 Wasserboxer with the single Pierburg Carb and I recall that I had a tough time getting that to pass emissions. The MOT tester would advise me to take 'Amanda' for a 'good thrashing' along the M62 Motorway then come back to retest the emissions which were then OK.
A good friend owns a '73 Westy with a 96mm Big-Bore Kit. The Van drives well but the twin Solex are getting a bit tired so maybe the Weber Progressive may find a new home there as the owner is not exactly flush with cash.
And IIRC Pre-1975 vehicles are NOT tested for emissions here in Blighty

Maybe see you at Tatton Park this Sunday?
I'll be on the KGOC-GB stand with my '73 KG Coupe

Rick
_________________
Current owner of 1980 T25 Westphalia Joker.
1973 Karmann Ghia Coupe - Semi-automatic!!
1983 Trabant 601S Sedan

Daily Driver - 2024 Dacia Duster Journey - Automatic

[orwell84]

The ICT’s I had were great when new. There is a good article at way out Westy in setting them up. The progressive works decently for warm weather, but needs preheat for anything cooler. If it’s a fair weather camper, taking the time to warm it up before hitting the road is less of an inconvenience. Not so much if you expect to hop in and drive to work on a cold morning.

[chaddhamilton]

With the help of a few folks on the forum, I was able to build out a much better progressive setup which has TOTALLY eliminated the lean conditions of cycliders 1 & 3 and provided more response and dare I say power to my 73 bus with a 2.0

Anyone looking to spend the time to do it, this proved worhtwhile. I'm not a great welder, but I can get by. I iunderstand that a lot of folks dont have a welder at home, but I think you could do this without a welder if you just used weber progressive intake rails. But I didn't wanna cut them up in case this shit went south and I had to revert my changes. So I found some FI intakes instead and welded. FWIW

What I had to gather to start
- EMPI Weber Progressive Intake for a type 1.
- 2 FI intake rails (I traded a friend for some stuff)
- 2 Y pipe collectors that are 1 3/4"(in) to 1 1/2"(out) (amazon)
- Heat wrap
- 1 1/2" fuel hose (amazon)
- 12v 12w heat strips (amazon)
- 12v relay

Fortuately I have a spare motor on a stand so I was able to build everything on it, then transfer it all to my bus when I was happy with it.

So this is what I started with:

I cut the intake rails down and tapped the intake for my brake booster:

I then attached a intake rail, temp fitted the y-pipe and carb, and started cutting and rewelding to make the intake rail meet up in the correct orientation...i only had to cut and reweld cylinders 1 & 3 pipes.

Once everything was fitted and nice and snug, i pulled it and attached the 12v heat strips to the carb manifold and later wrapped it with insulated tape.

And then I bolted it all back on the temp motor and made a carb base.

I already had an intake heat box setup, so I just had to put everything in and wire up a switch to control the heat stips. I need to clean it all up, get a thermo controller and whatnot, but I was really just trying to get it fisnished before the cold front comes in. Here's what it looks like in the bus.

The first 10 minutes(it was about 40f out when I started it up), it's the typical weber progressive rough-running because the y-pipes are not heated yet. I bought 4 more polyimide heat strips to add to each rail and I'm thinking that will help on the warm up. After they get warm from the heat taken off the exhaust, it's like butter. I did a plug chop doing 50mph and every plug was golden brown...i about shit as I'm used to 1 & 3 being on the white grey side.

Anyway, I hope this provides some helpfuil insight on how to do this. It was about $220 in parts, a real fun time putting it all togtehr, and totally worth it! Big thanks to (busman78) for helping with the intake planning.

Do good deeds, dudes.
Chadd

[busman78]

I like it, bit jealous, nice work.

[aeromech]

I’ll have a fairly new single carb available for purchase soon. Removed from a 1972 T4
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[Wildthings]

[SGKent]

couple observations.

Good job.

The center plenum will flow more evenly than any progressive I have seen to date on TheSamba. The whole idea of a progressive is the word itself, "progressive." A single smaller venturi/butterfly is idle and low speed, then as the need for more air and fuel is needed, the secondary opens. We used to open them simultaneously on the race car but there was so much cam that the idle had to be up at 2000 RPM just to keep the plugs from loading up. In a scenario like that, it is usually wide open or braking so it worked well. In a bus a mechanical linkage that opens the secondary is best. Some progressives have a vacuum secondary. Your center plenum is done in a way that the flow to all cylinders is pretty balanced.

The only caveat I would make is that the air from the heat exchangers is Really hot. I would be leery of using it into a carb body. I had a CJ7 that pulled heated air from around the exhaust - much less heat than you will have, and on a sustained climb up Jacumba grade in San Diego County in winter with it snowing, there was so much heat sucked in it started a carb fire from the coating on the aluminum heat tubing, and melted aluminum as the fuel became a blow torch. Find another place to pull heat from, and use a vacuum motor and door to turn it off when you don't need it. The heat strip is fine.
_________________
"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[Wildthings]

[orwell84]