hey i have a flat spot in my kombi 1600 its just off idle when u put ur foot to the floor i read in a zeitschrift mag that its usually the jets so what should i upgrade to its a 34 PICT-3 carby (doesnt look like its a solex carby)
cheers
rhys
p.s. bloody rain ill check what brand it is when it stops

hi rhys
when I drove it to brisbane it did that as well yoiu had to play with the throttle to get it going not sure what the problem was once it picked up some revs it was fine and cruised all the way up there just on take off
marcel

hey
yer i know (quick little drive up and down the rear lane )
got the 2L running today ripper of an engine!
cheers
rhys

More info Rhys

What sort of motor T1 or 4
What carbs?
009? - notorious for flat spots when combined with 34's

What is the throttle bush like?
If it is loose it will suck air like Madonna on a ......

There are several answers.... more info please:bounce

its a 1600 tport running pict 34 (looks pretty new) and standard distributor
marcel

Then i would be looking for a vac leak somewhere.

What condition are the manifold boots in?

How good is the 34 Pict? - no leaks at the throttle shaft?

I have a 34 PICT as well Rhys and have had endless problems with it. It wasn't only the carb but mant probs in combination. I couldn't get it to idle - turned out it was the idle screw ruber o-ring jammed throughout the throttle body. Apparently mine has a 1500 dizzy (Vac adv) which isn't the best for the 34 and better for a 30. The 009 is the prefered for the 34.

I hope you have better luck than I with your flat spot. I haven't had a flat spot yet but give it time - it's running out of things to sh!t me with.

A larger idle jet will be the obvious answer if you don't have a vacuum leak - it can also help to cover the flat spot caused by a 009 if that's what you have. If so, you're still gonna have to get used to driving it hard: that's what 009s are for.

standard vac advanced dizzy, no vacuum leaks etc, how many tuerns do u take out the fuel mix? and any other carby tuning turns? give here a tune up and see how she goes!, anyway i just bought myself some kads for it
cheers
rhys

You said the carby looked new - that will almost certainly make it a Brosol (Brazilian Solex) 34PICT/3.

These are usually delivered with lean jetting (an emissions thing) making them hard to tune, and since you have a heavy-bodied bus, that changes things a little too.

For a bus with 1600 and vacuum distributor, you need a 65 idle (55 for a beetle), 127.5 main jet and about a 60 air correction jet.

I presume the vacuum distributor is in fact "stock" and is the Single Vac Double Advance (SVDA) type? With a smallish vacuum canister on the side?

I mention this because the earlier single vac (vac only) distributors were used on 68-69 kombis but had a larger vacuum cainster which matched the 30PICT/2 carbies they used. The vac canister size must match the carby size (large vac for the smaller carbs and smaller vac for the 34) or you get an incorrect advance signal, and so you either get a flat spot (insufficient advance) or pinging (to much advance) as you open the throttle.

Since you've now bought yourself some Kads, what are you doing with the near new 34 - does it need a new home (pleeeease :-)

yer prolly will need a new home ill give u a definate answer when i get the kads and make a decision!
cheers
rhys
p.s. will kads work with the advanced dissy?

It is "easier" to whack a 009 on

You can tap for a vacuum port on the Kads - but dont ask me where.

Maybe Stan knows or scour the http://www.lowbugget.com  site (AJ Sims)
I know he does it. Maybe you could email him?

you need to tap into both manifolds, run them into a tee to get a good vacuum.

Quote:

Originally posted by kombi_kid yer prolly will need a new home ill give u a definate answer when i get the kads and make a decision! cheers rhys

As to where you tap the kads, it's just above the throttle plate at the closed position (you don't want the vacuum advance at idle.) A look at the pozzie on your stocker to give you an idea; you'll see a 1mm hole about 1mm above the closed position of the plate, offset from the idle/progression holes (it should not be above/ below any of them.) Many run a single line (from a single carb,) some run ports on both - you should only need the two if you have a fairly lumpy cam.

Back in the 70's when VW went to twin carbs on a type 4 they tapped into the manifolds of both sides for the vaccum signal. Good enough for them... good enough for me.

The twin Carbs on the type 4 motored Kombi only used a vacc takeoff on the left carb for distributor advance
the larger connection on each manifold is for the brake booster
Jeff

Amazer,

Jeff's right - you can't take a distributor vacuum signal from the inlet manifold - that puts it UNDER the throttle plate so you get full advance with the throttle shut and almost no advance with the throttle wide open. It has to be above the thottle plate so it relates to the airflow through the main venturi. That's where it is on all Solex carbs - just under the venturi and above the throttle plate.

And 70Autostick, the idle and transfer ports are on the BOTTOM side of the throttle plate - no where near the vacuum port, which is above the top edge of the closed throttle plate (which is oval and sits at an angle when closed).

Sorry to go a bit stray, but does anybody know the difference between 34 pict-3 and 34 pict-4 carbs? I've got one and I notice what looks like an extra place to put a hose on the side of the carb, but there's no hose on it.

Cheers
Josh.

I think the 34 pict4 is from a golf or something, it has more emmission type crap hanging off it.

Rob, I noticed you said the 34 pict3 is jetting lean on the idle jet, didn't I say that in another thread and you argued it wasn't actually lean it was just closer to 14.7:1 than the other solexes :P

Anyway, I agree the 34-pict 3 has a leanish idle jet. It works fine with the stock vac dizzy and stock exhaust.

3 things make it cause trouble, a vacuum leak (really leans it out), a 009 and a aftermarket exhaust (also effectively leans it out).

So what exhaust are you running?

I would check what size the idle jet is and then bump it up one size and see how it goes.

Aussiebug, if you have a set of Kads, you'd better have another look (and hold them up the right way this time.)

The 34pict-4 was used on at least the '74 "California" engine (look in your Bentley Manual.) It's the "emissions" carb, with two vacuum ports (I think the second, retard, port was manifold vacuum - but I'm going off old memories here,) - I'm not sure what Australian engines they were originally used on, but I have seen one: it would work using the regular vacuum port, but it ran rather lean.

70autostick,


Re the idle port positions, I'd switched my thinking to Solex - not kads - my mistake.

And yes - the 34PICT/4 is a California-only carburettor to meet their stringent anti-polution laws.

It runs a little leaner than other forms of the 34PICT and usually has a throttle positioner attached which slows the throttle closing when you lift off - if I remember right that's what the other vacuum port it for - the throttle positioner does use a vacuum can.

Baja Wes,

Re the "lean idle jet" comment. The original post was about Kombi, not a bug and the type2s usually had a 65 idle jet rather than a 55 (same with the KGs), as the heavier body presumably needed the richer jet to help get it moving. So for THIS application, the 55 idle jet is a little lean, but would be normal for a bug.

Sorry I was in a bit of a grumpy mood last night, should have thought of the terminology confusion that can arise when the progression ports are called idle/progression. To anyone else reading, there are possibly two ports below the butterfly, an idle mixture bypass and on some carbs, an air bypass.

hey wes
its all standard exhaust dizzy etc and there doesnt seen to be a vacuum leak! ill go and grab a spare idle jet from the mechnic and see what happens!
cheers
rhys