TheSamba.com :: View topic - original 72-74 dual carbs

Tue Nov 25, 2014 7:44 pm

ive been working on a 72 asi bus

the gaskets on carbs have failed and so

Im planning on rebuilding some carbs out of the spare parts box
and just swap them out

I have several carbs and parts and really want to make sure
im installing correct complete 72 carbs

and not just follow the previous owner in making something work

here are some pics of the carbs that came on 72 bus

and here are some pics of the spares I have

carb #1

carb#1

notice the square on both sides ???

carb #2

carb#2

carb#2 looks the same as whats in the bus (except for the very bottom not pictured)

the pass side carbs I have look the same but the bottom is different on both ?

one of the carbs has the flat part that looks like something connects to it
the other carb has that bottom piece round

same gos for the driver side carbs
the one that looks the same as whats on the bus, has the bottom part
with the flat plate
while the one on bus has nothing

can you guys help me make sense of what makes 1 complete correct pair of 72 carb

ive read that 72 carbs are slightly different fron 73-74 carbs
but cant seam to figure out what to look for

Tue Nov 25, 2014 8:08 pm

Busdaddy knows all....

Xevin is currently building a set for his 72 westy.

Amskeptic wrote a killer write up on 72 carbs.

Ill let someone else post links, as im on my phone at the moment...

Tue Nov 25, 2014 8:44 pm

Yes Busdaddy or Colin would know. I'd tell you Colin but he is busy counting dots on a ceiling right now.

:lol:

Tue Nov 25, 2014 9:39 pm

I actually was a surrogate owner of a 72 Bus in a previous life ..but not an expert...

The extra pieces on the right hand carb in the pic look like ports for EGR ( emission control stuff). 72-73-74 were transition years and a lot of cars added EGR in these model years.

Those dual carbs we're subject to throttle body wear..the only solution is to get someone to rebush the carb throttle plates.

Tue Nov 25, 2014 10:06 pm

I'm at work. Will hit you back later if you need some pics of mine. Take a look at ratwell for his solex rebuild it's a 72.

Tue Nov 25, 2014 10:12 pm

SGKent wrote: Yes Busdaddy or Colin would know. I'd tell you Colin but he is busy counting dots on a ceiling right now.

:lol:

whatd he do?

Tue Nov 25, 2014 10:27 pm

I gather you're looking for the correct '72 only dual setup? I don't remember if they had EGR ports that year, but you can get a head start by checking for an accelerator pump adjustment screw- that would indicate a later model. The early early ones had a cotter pin. Also, '72 cross bar synchronizing is done with a screw on the left, later models are done on the right. I don't remember if they moved/mirrored the mechanism, but the sides did change.

And just like the 34pic3, the idle circuit (central idle circuit in your case) can mask your throttle shaft wear until you get them professionally rebushed. No need to lose any sleep here unless yours practically rattle.

Robbie

Tue Nov 25, 2014 10:28 pm

Stuartzickefoose wrote: SGKent wrote: Yes Busdaddy or Colin would know. I'd tell you Colin but he is busy counting dots on a ceiling right now.

:lol:

whatd he do?

http://www.thesamba.com/vw/forum/viewtopic.php?t=580399&postdays=0&postorder=asc&start=0

Tue Nov 25, 2014 10:36 pm

The 72 carbs did not have EGR. :roll:
76 Westy, if you are in need of any detailed parts then, don't hesitate
to reach out to me as i have quite a collection of 72 ONLY carb parts.

You have helped many here and i will be more than glad to help You.

Chris

Tue Nov 25, 2014 10:50 pm

Ha ha ha ha....., oh damn, now I've got to live up to a standard :oops: :P . I don't have a lot of literature in hand that matters on the early PDSIT's aside from some credible internet sources. Personally I haven't seen those throttle bodies with the flat spot on the side on unmolested 72's, quite a few on 73/74's and I suspect they were a superceded replacement part for all models. I have yet to see the flat spot actually used, it looks like a place for a bimetal valve of some sort that hasn't been fully machined like the fuel pump pads on FI engine cases.
My quick and dirty swap meet method for discerning early carbs from later ones is the holes in the throttle arms and the brackets for return springs, 73/74 used a short spring that was entirely contained on the carb, 72's originally (I think) had none but I've seen a few with springs down to the tin that I suspect were a dealer fix.

Tue Nov 25, 2014 11:13 pm

This may help:

http://www.thesamba.com/vw/archives/manuals/solex_34_pdsit_2_3.php

Tue Nov 25, 2014 11:16 pm

asiab3 wrote: I gather you're looking for the correct '72 only dual setup? I don't remember if they had EGR ports that year, but you can get a head start by checking for an accelerator pump adjustment screw- that would indicate a later model. The early early ones had a cotter pin. Also, '72 cross bar synchronizing is done with a screw on the left, later models are done on the right. I don't remember if they moved/mirrored the mechanism, but the sides did change.

And just like the 34pic3, the idle circuit (central idle circuit in your case) can mask your throttle shaft wear until you get them professionally rebushed. No need to lose any sleep here unless yours practically rattle.

Robbie

this is whats on my mind
and seeing that for 1 reason or another nothing matches

I want to make sure im putting back together a correct 72 carb

im a fuel injection kind of guy
and don't have a clue as to where to look to see if
its a screw or pin

then seeing all the variations in carbs makes it confusing

I think I need to start with knowing what all the variations are on
the carbs I have
then figure out what is a 72 carb compared to a 73-74

Wed Nov 26, 2014 12:04 am

busdaddy wrote: Ha ha ha ha....., oh damn, now I've got to live up to a standard :oops: :P . I don't have a lot of literature in hand that matters on the early PDSIT's aside from some credible internet sources. Personally I haven't seen those throttle bodies with the flat spot on the side on unmolested 72's, quite a few on 73/74's and I suspect they were a superceded replacement part for all models. I have yet to see the flat spot actually used, it looks like a place for a bimetal valve of some sort that hasn't been fully machined like the fuel pump pads on FI engine cases.
My quick and dirty swap meet method for discerning early carbs from later ones is the holes in the throttle arms and the brackets for return springs, 73/74 used a short spring that was entirely contained on the carb, 72's originally (I think) had none but I've seen a few with springs down to the tin that I suspect were a dealer fix.

thanks busdaddy
so that bottom flat piece just means
that the carb is probably from a 73-74 and has no function

Quote: '72 cross bar synchronizing is done with a screw on the left, later models are done on the right.

Bentley says pretty much the same thing

what I don't get is
left right of driver side carb
or left carb right carb

Wed Nov 26, 2014 2:09 am

Ok I'm off work and tired so I might be reading this wrong. There is a picture of 34-PDSIT. This is not part of this particular carb set up for a 72 bus. Although it might work. But the rebuild kit is different. Can you tell me which one of your carbs is the PDSIT 32-34-2 (side with the throttle cable and dashpot) (do you still have a dashpot?) and the 32-34-3? If you can circle the bits you question in the photo. I would help you with photos of mine. Just want to make sure your terminology is what I'm thinking. Mines all laid out in my basement and we can compare notes. Mine might have been a collection of mish mashed parts too. But all my research tells me, mine is tip top. By the way I'm looking for pictures of balance tube and brake booster tube connections and parts.
Also research http://www.itinerant-air-cooled.com/viewtopic.php?t=4062
Not so much this particular link. But the site. I haven't explored this either. You probably have all the connections but I'm going to replace my Weber progressive on a 76 2.0 L engine in my 72. Anyone with jetting suggestions for my application would be a bonus. I would gladly hijack this thread :twisted:
Kidding I would make a new one.
Oh and while you are doing all this, have Tim at Volkzbitz rebush them.
Anyone with knowledge of these will tell you that's were the gremlin lives ( the bushings). I totally understand the confusion with these parts but rebuilding the carbs themselves look pretty straightforward as long as you have all the correct gear. So I will you hit you up later for some tips.
Good luck. Again let me know if you need some pictures.

Wed Nov 26, 2014 6:01 am

Tin at Volksbitz can also rebuild and rebush those carbs. I don't know what he charges but it would still be worth it to me.

Wed Nov 26, 2014 7:53 am

The rectangular deal on the throttle body is the mounting boss for a hot idle stabilizer that was used on automatic transmission buses so they wouldn't stall in the heat when you were in sitting in gear. Somebody just replaced their throttle body at some point in the carb's history and all replacement throttle bodies have those mountings cast in.

The square on the left carb cast near the central idling circuit is a vestigal organ that was superceded by the increasingly rare-to-find idle enrichment box found on some left side carbs the little box with an electrical spade connector on it.

These carburetors work beautifully when set up correctly, and you definitely like having that big ol stupid oil bath air cleaner to give you air filtration performance second to none.\
Colin

Wed Nov 26, 2014 9:00 am

Right on Colin :D As usual excellent info. Heads up on Volkzbitz. Tim will only rebush PDSIT carbs. Not rebuild. PICT carbs he will rebuild and rebush.

Wed Nov 26, 2014 1:16 pm

the first set of pics is the carb in my 72 right now

carb #1 and carb #2 are both driver side
and I want to use 1 of them to rebuild and replace carb currently in bus

the last pic with 2 carbs in it
are both pass side carbs (im assuming, please correct me if im wrong)
although the manifold is on backwards on 1 which makes me feel insecure

Quote: The square on the left carb cast near the central idling circuit is a vestigal organ that was superceded by the increasingly rare-to-find idle enrichment box found on some left side carbs the little box with an electrical spade connector on it.

so in calling it vestige
it is ornamental and more than likely from a 73-74

the way im interrupting things right now is
unless the 72 was an automatic it should not have the flat part on throttle body
but if it does, its no big deal and there is nothing i have to cap off by having it

the extra square on the right side of the left carb
was a add-on to 73-74 carbs that was not very useful
so a proper 72 carb will not have this either

i think i see what busdaddy is talking about with the spring.....
i have a AW engine (core) that still has complete egr and smog pump installed and unmolested
the carbs on this engine have a extra little piece on bracket for a spring
both carbs have the flat part on throttle body
and the extra square on left carb

which means a correct 72 carb will have the smaller bracket without a spring
on the throttle

Wed Nov 26, 2014 1:20 pm

Xevin wrote: Right on Colin :D As usual excellent info. Heads up on Volkzbitz. Tim will only rebush PDSIT carbs. Not rebuild. PICT carbs he will rebuild and rebush.

what is the difference between a

PDSIT carb and a PICT carb ???

Wed Nov 26, 2014 7:30 pm

They are both simple single barrel carbs. The difference is mostly in the castings and drillings, but they share some universal parts like pilot and air bypass cut off solenoids. VW used the PICT carbs for single carb applications, and PDSIT carbs for dual carb applications like the Type 3 and Type 4 motors.