I have put a hot dog style exhaust on my 2.0l Kombi, which has the standard Sloex 34 PDSIT/2/3 carbs on it.
It goes better in general, but has a little bit of a flat spot on small throttle settings. I'd say it would be at about 1/4 throttle, or maybe even less. If I'm driving up a slight hill with a little load on the engine, give a slightly jerky feel. Nothing too serious, but irritating. It goes away if I put my foot down hard, or if the ground levels out so less throttle is required.
I figure it's a jetting issue, though i don't know if it's rich or lean. But more to the point, I don't know which jet in the carbs control this area of performance. I have a Haynes manual with an exploded diagram of the carb, and the only jets mentioned are the main, and something called the air correction jet.
Any ideas as to where to beging to get a bit smoother running ?
Thanks,
Kommer

from what you said it sounds as the idles are a poofteenth small you will need a set of reamers to enlarge them. i think they are .45 standard and i would try .475 next and they are stuck in the end of the idle cut of solenoids on the sides of the carbs..But before you play there make sure the rest is ok and particularly the throttle shafts,you can get them rebushed fairly cheap if you disassemble them yourself:beer:beer:beer:beer

Also good to check the vac advance on the distributor. The basplate can get worn also, and the shaft can wear needing rebushing.

You will need to change main jet and air correction jets. I've recently done this after fitting a new extractor and muffler to my 2 litre. Go the next size up to start with, test and then adjust accordingly. There's a bit of fiddling around, but you'll notice performance gains. And contrary to popular opinion, your fuel consumption will not be adversely affected. In fact mine improved slightly because the engine was running better.

Might also pay to check your idle jets (as suggested in an above reply). I now run 60's, this makes it a little richer, but also helps avoid lean mixture in hot conditions, and compensates for the crap petrol we're sold at the pumps.

Many thanks for the helpful comments and suggestions. Just spent a useful couple of hours with the Kom and she's now running sweet as a nut.
I took the idle jets out to .5mm which got rid of the frightening bang bang pop crackle on the overrun. I then checked through my collection of distributors and cobbled one together with nil play in the shaft, and the combination worked wonders.

But I'm interested in VWMA 'Editor's comments about the main jet and air correction jets needing adjusting with open extractors. What size mains did you end up using ? What are the symptoms of leanness on the main ? I've always thought the engine is a little flat at the top end. I pulled out the mains and they are 132.5s. I have some Mikuni 110s, and a 1.4mm drill. Should I give them a try ? I guess it's no big deal to try it and see, but I don't want to wreck the 110s if the enging is already OK.
Thanks again,

Kommer

Glad to help. I know of a few times when carbies were blamed for problems actually caused by distributor wear.

Well, I went to 140 main, 160 air, and the next size up needle and seat.

And just checking - you are running 2 litre carbies on your engine, not 1800 types?

This is weird- I havent visited this site for onths and I have a carby question and this thread was top of the list
I had my van serviced and the mechanic said I neeed a carby overhaul.
He said the engine has no power and when I turn the engine off I get some 'running over'
Also engine runs uneven when idling

What the hell does alll this mean?
I have a 2 ltr Kombi with 2 karbys
Its 1977 delux with no 'add ons'

i rekon all that means its time you found a new mechanic,did he do any vac checks etc or just tell you its stuffed:beer:beer:beer

^ it was a new mechanic as my usual one wzs on hols still

ive got similar problems with my van... same deal... 77 bay with little bit of a flat spot and it pops and crackles as i slow down... carbies were rebuilt and its still doing it. I dont trust the guys that did them anymore because they forgot simple things like... say... oh i dont know... throttle return springs... nothing obvious of course. :P