Any common causes for a carb to not want to idle? It's a 30 pict.

Ooops - posted this on the other question

I am stealing Aussiebug's thunder (sorry Rob) but have a good read here and see if it helps

http://www.geocities.com/aussiebug1970/30PICT2.html 

Don't feel sorry for "stealing my thunder" Blue - I'm happy to have my articles posted if it helps another VW owner.

Well i've just spent the afternoon rebuilding my carby. And it still wont idle!
I have pressure tested the manifold, set the timing (static 0°) and set the idle to high. It seems to have a slight miss every now and then, above 2000 rpm.
As soon as you take your foot off the gas, it dies like turning the key off.
Any ideas?

sorry - why 0 degrees (how did you do the degrees symbol?)

what motor is it ? a 1641 yes?

and a 009?

why not 7.5 ?

What about spark?
leads?
cap and rotor?

Has this only happened since you took the duals off?

did this carb ever work?

I normally set it to 0° as a starting point and tweek from there, also I know that it runs at that setting.
I get a good spark, from what I can see through the clear dizzy cap, and runs well and smooth at high revs, apart from a very slight miss which I can hear every now and then.
This carb is what was on before I tried the duel carb set up and worked fine.

To get the ° symbol hold down the Alt key any enter 0176 on your keypad, this method gives you access to the extended ASCII keyset, just try it with different numbers. ±²³´µ¶·¸:thumb

Athough you've rebuilt your carb, it's possible a passage is still blocked. The best way to check this if you have the gear is to visit your local wrecker and pick up an EGO sensor, then tap your exhaust and fit it. I'm not sure if Dick Smith still sell them, but Jaycar and Altronics still have a kit to read the mixture reading from this; if not, many auto stores now sell a ready-made unit to do it.

Another thing to consider is your clear dizzy cap - they are notorious for leakage. Just fit an old stock one to prove this isn't the fault. A leaky dizzy cap usually causes problems at low to mid revs, but it can be anywhere really.

aha!! so after abusing the carby all this time i find i have a crack in my dizzy cap. Bugger bugger bugger:bounce:bounce

It doesn't even need to be cracked - the clear caps seem to have a problem with cross firing - maybe the plastic they use?

Yes, it's the plastic they use, it forms invisible carbon tracks rather quickly. The good-old bakelite caps from Bosch may not look as pretty, but they work a lot better, a lot longer.

I tried another Carb, that didn't work at all. so I rebuilt my 30 pict (fully). Set the timing (+30° max at 3500rpm) yes a 009.
Set idle at 850rpm, idle air screw at 2.25 turns out. cleaned clear 009 Cap. Now I have an idle BUT every now and then it will almost stall then idle up again? Maybe I'll change the condenser?

First, borrow a stock Dizzy cap - cleaning won't fix it. The condensor usually won't allow the engine to start (or produces misfiring at higher revs first,) but it's worth looking at down the track.