Adjusting Dual Carbs. . . for rustybus and all

[busdaddy]

You are correct on all assumptions, there are 2 balances you need to accomplish with the linkage, one at idle which it seems you have a handle on (that's what the stop screws do) and one with the throttle open a little so it's being opened by the cable (that one requires linkage adjustment to balance as you are off the stop screws).
The 3rd carb (aka the CIS) is to add idle mixture to bring the idle to a driveable level, but you still have to balance the individual stop screws and mixture screws on the bases first to achieve a smooth and even slightly lean low idle, then bring it up speed and mixture wise with the CIS.

For the white plugs modern gas doesn't play like it did when these vehicles were new, increasing the main jet size by 5 numbers wouldn't hurt. Can we see a picture of these plugs?, white alone isn't a bad thing but evidence of burning is, older plug charts that assume leaded gas don't count today.
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[tomfreo]

These plugs (W7CC) were installed new c.15,500km/9,600 miles ago.

What effect do modern auto petrols have on the plugs? I use what's called "regular" 91RON unleaded here which I believe is about 87AKI.

I also use a 'valve saver' lead-replacement lube although I'm not sure whether there's any point spending the buck a (full) tank it costs me.
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'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp

[tomfreo]

Does anyone know whether modern fuels make diagnosis of plug colour different from what it's been before?
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'77 Kombi 2L dual carbs
'61 Bug 6V 1600sp

[busdaddy]

To start with no lead, that's what made those thick fuzzy white deposits on many of the plugs on the charts. It takes hundreds of miles to build up any amount of deposits and most of that will just be carbon, if it's lean you won't see anything at all aside from erosion and possibly cracking of the insulator. If it's rich they will be black all over.

Those plugs don't look too bad at all for an aircooled, possibly a hair on the rich side but that's better than too lean, the one closest to the camera is using a little tiny bit of oil.
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[SamboSamba22]

Super Duper Freaking Ecstatic I came across this today! Thank you Colin!
Sam
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The Bus Barn Ltd. Co.

Oct. ’67 Double Cab (’68 Crew Cab)
[url=http://www.vw-mplate.com/mplate-44412.png]Click to view image[/URL]
March '69 Delivery (Panel Bus)
[url=http://www.vw-mplate.com/mplate-44414.png]Click to view image[/URL]

[Yarkle]

Ok, im sending my dual carbs out to tim to get rebuilt and rebushed, quick Q:

Im not sure (the setup came off a bus that "ran when parked") that the idle enrichment valve 021 129 052 A actually works, and Tim doesnt have any kicking around .

I have a somewhat nicer set of 73 carbs that do not have that idle enrichment thingy, and i have to use the arms and the stove mount off of these anyways to have return springs, since i dont have 72 only tin.

I think the 73 carbs are in better shape, but im using the 72 oil bath, vacuum lines, central idle, etc.

one of my 72s:

one of my 73s

Ive see posts that refer to deleting or disabling the idle enrichment valve , so should i just send in the 73 ones, effectively deleting this (this is the other 72 carb)

and then just swapping this style (which i think is for the 73 with EGR, whihc im also deleting , as im running the 72 setup)

for this one, which gives me the return springs mounted to the carb arm and the stove, instead of arm and tin

(the one not circled)

so that way i get the return spring on the carb itself, instead of like how the 72s were

thanks to mayor ratwell

if i do this, is there anything i need to do differently vis a vis tuning? I read that Colin said they are set too lean, and the idle enrichment valve works to correct that problem when cold
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Tilda the Mustard Tigress 1973 Squareback (o'''^'''o)

https://www.thesamba.com/vw/forum/viewtopic.php?t=771024&highlight=

[busdaddy]

The 73 style carbs are likely a better choice, you may have to reduce the size of the bleed holes in the throttle plates since they are meant to idle ~15* ATDC, other than that you should be able to tune them properly.

And for all those who say VW never used clamps on the fuel lines look closeley at the second pic from the bottom
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[Yarkle]

thanks!

ok, ill tell Tim that, but just delete the idle enrichment thing (well, if i use the 73's, its not even on there) and the EGR hookup arm on the stove mount
and everything else should be good to go with the oil bath? how much reduction would you say? (or will tim just knwo what to do if i tell him ill set the idle at 15 deg?)

DOHW!!!

the picture busdaddy is referring to i deleted to make it more clear as to wha ti was saying, here it is:

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Tilda the Mustard Tigress 1973 Squareback (o'''^'''o)

https://www.thesamba.com/vw/forum/viewtopic.php?t=771024&highlight=

[busdaddy]

It depends on what distributor you are using, if you go with the 73 DVDA it needs the larger holes in the throttle plates, the 72 DVDA still retards, but not as much, or if you are using a SVDA or some aftermarket distributor it will need even smaller holes.
The enrichment is nice on cold days, but if you can wait 5 minutes for it to warm up when it's near zero outside you won't miss them. It's only there for instant driveability in the middle of winter, not many bus owners drive on days like that now, a couple minutes poking the pedal to warm it up will give you time to scrape the frost off the inside of the windshield properly and that's just safe motoring!
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[Yarkle]

ok, ill have to dig that out and find out which one i picked up (bus currently has a weber progressive on it, so its got an 009)

and if its zero out, that means theres that nasty road treatment, so i dont foresee being out in it unless absolutely necessary

So if im following you:

73 distributor: Distributor: VW 021-905-205J, Bosch 0231 173 009 or 010 > 021-905-205N, 0231 181 005

just leave the plates as is,

but if i have a 72 distributor:

Distributor: VW 021-905-205E, Bosch 0231 173 005

then i have to have him narrow down the holes?
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Tilda the Mustard Tigress 1973 Squareback (o'''^'''o)

https://www.thesamba.com/vw/forum/viewtopic.php?t=771024&highlight=

[busdaddy]

It'll be easier to tune if you do, measure the difference between the 2 sets of carbs you have now.
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[Amskeptic]

[Yarkle]

Colin, given the differences in condition between the 72 set and the 73 set, that was kind of my "waffling" point. It looks like i can just swap out the "stove" mounting points and the throttle arms to have the 73 style return springs. Ill have to dig out the distributor and see what i have.

I guess if i have a 72 distributor i could just use the 72 carbs, if i have the 73, ill go with the 73 carbs?

Pros? Cons?

I value both of your opinions, and i really am on the fence with either set.

EDIT: Ok, i have the 021-905-205E 0231 173 005 Dizzy..

so go with the 72s? and if the valve works, it works, if it doesnt, it doesnt?

OR

go with the 73s and narrow down the holes halfway between where the 73 and 72 are for reference.

OR....Since ive got like 5 extra 72 carbs...send him the throttle plates from 2 of those and have him install those plates into the 73 carbs?
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Tilda the Mustard Tigress 1973 Squareback (o'''^'''o)

https://www.thesamba.com/vw/forum/viewtopic.php?t=771024&highlight=

[Amskeptic]

[Yarkle]

The holes was referencing how busdaddy had said to narrow down the holes in the throttle plate if i use the 73 carbs with the 72 distributor. But then i realized i have so many 72 carbs i could probably just send Tim a few extra plates.

i have the oil bath cleaner, linkage, manifolds, everything else for a 72, i just happen to have what seems to be a better set of 73 carbs.

heres a few more pics, but overall, the 72 ones look "worse", even though both sets supposedly came off of running buses

72:

73:

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Tilda the Mustard Tigress 1973 Squareback (o'''^'''o)

https://www.thesamba.com/vw/forum/viewtopic.php?t=771024&highlight=

[Amskeptic]

[Yarkle]

Ok, ill do that, maybe just send both sets to Tim and have him make a judgement call.

But to clarify, IF the 73s are the better set, should i:

A. have Tim put 72 throttle plates in while he is rebushing it, since i have the 72 dizzy, or is that even a possible thing to do?

B. Or just change the timing to reflect the bigger holes in the 73 plates?

C. Or have him try to compromise between the two and see if he cant narrow down the throttle plate a bit?
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Tilda the Mustard Tigress 1973 Squareback (o'''^'''o)

https://www.thesamba.com/vw/forum/viewtopic.php?t=771024&highlight=

[airschooled]

[Yarkle]

ok, ive got some weirdness going on...I just checked, and the holes on the throttle plates on both the 72 and the 73 seem to be the same size. I went through some of my nastier carbs and found two of the 73s actually had smaller holes, but only on the #2 side.

AND it looks like my idea of using the 73 arm return springs might not work, as it goes a little farther outward (or inward) than the 72 arms are, so im sortof stuck at that point. I dunno if i can just rotate the 73 stove mounts and get it to spring from that direction?

Im about to just say f#ck it and go with IDFs
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Tilda the Mustard Tigress 1973 Squareback (o'''^'''o)

https://www.thesamba.com/vw/forum/viewtopic.php?t=771024&highlight=

[busdaddy]

Why not just send all of it to Tim and let him decide what's going to produce the best final product?
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