TheSamba.com :: View topic - Question about adjusting a 34 Pict 3 carb

Sat Sep 20, 2014 10:24 am

I've searched the forums and adjusted the choke/idle/airflow
I have the timing set correct and the SVA distributor with electronic points is advancing correctly

Thing is I have an intermittent flat spot when giving it gas off idle
Like when I slow to a stop after running it down the street and take off again, it will bog for five seconds or so and then start going good again.

I did the pop rivet in the butterfly valve hole and it seems a little better

I don't know if it's low on fuel when it's bogging during that time or if it's getting too much fuel at that point

how do I tell?

What's the fix?

What do you guys think?

Thanks!

Sat Sep 20, 2014 1:17 pm

Do the preheat tubes running across under the manifold get too hot to touch in a couple minutes of running?
You can try playing with the acelerator pump adjustment and see if moving it towards + or - makes it better but I suspect you'll need to go up a size or 2 on the idle jet.

Sat Sep 20, 2014 4:01 pm

busdaddy wrote: Do the preheat tubes running across under the manifold get too hot to touch in a couple minutes of running?
You can try playing with the acelerator pump adjustment and see if moving it towards + or - makes it better but I suspect you'll need to go up a size or 2 on the idle jet.

yeah the preheat tubes get pretty hot
I just adjusted the carb again and took it for a ride
I can feel a spot on the accelerator pedal where it seems to catch a bit and when I push past that it stalls for a second then goes again
I'm gonna take off the air filter right now and take a llok at what the accelerator pump is doing

Sat Oct 04, 2014 5:02 pm

I rebuilt the whole carb today and noticed it only had a 120 main jet in it
I grabbed a 130 from some dual brosols I never got around to putting on and the flat spot is gone... it pulls hard in all gears
but now it's running rich at idle and the small air screw doesn't seem to have any effect, I can turn it all the way in and out with no difference
what's up with that?

Sun Oct 05, 2014 7:25 am

Pull the pop rivet out so you can get the throttle plate almost completely closed like the carb is designed for.

There are many articles on how to properly adjust a 34 pict. The first important step being to adjust the throttle plate.
The idle speed is adjusted with the air idle screw and if the throttle plate is not correct you won't get anything right.

Here is one of the articles I always used when I was doing my blow-thru turbo with the Bocar 34 Pict-3.

http://www.vw-resource.com/34pict3.html

I used the DVDA for just a short while and then switched to crank-fired ignition and it always idled good and I never had a flat spot.

The carb is in there somewhere.

Sun Oct 05, 2014 10:49 am

clonebug wrote: Pull the pop rivet out so you can get the throttle plate almost completely closed like the carb is designed for.

There are many articles on how to properly adjust a 34 pict. The first important step being to adjust the throttle plate.
The idle speed is adjusted with the air idle screw and if the throttle plate is not correct you won't get anything right.

Ok I pulled the pop rivet out and adjusted the throttle plate correctly... the small air screw is working now

It runs great but it's hard starting and super rich at that point
When I pulled the carb off the motor gas came out between the carb and manifold
I put a thicker washer on the float valve and it still does it. It had a .5 washer and I put .75
Do you think that new float valve is bad or should I try 1.0 washer?
thanks

Sun Oct 05, 2014 11:45 am

I had similar problems with a 'decade' brand 34'3.

I bought a new Bocar and all my problems disappeared!

Sun Oct 05, 2014 11:55 am

I was going to the dual brolsols I have or getting a weber or something but I was thinking of getting an ecotec motor for it this month and selling the 1600

Sun Oct 05, 2014 3:42 pm

Check your fuel pressure - should be around 3 lbs.