View original topic: Carb by pass screw
hale6968 Mon Mar 15, 2021 5:34 pm

What is the purpose of the large brass bypass screw above the volume screw on passenger side of a pict 30? Thanks

KTPhil Tue Mar 16, 2021 9:58 am

What is the complete model of your carb (-1 or -2)?

Nothing on the passenger side I know of, unless your car is RHD.

glutamodo Tue Mar 16, 2021 11:46 am

hale6968 wrote: What is the purpose of the large brass bypass screw above the volume screw on passenger side of a pict 30? Thanks

Now, there ARE NO adjustment screws on the passenger side (USA, left hand drive) side of the carburetor. As you sit in the driver's seat, one side of the car is left, the other right. You should use that as your orientation when you talk about where stuff is on the vehicle.

Now, it sounds to me like you are talking LEFT side of the carburetor, and if you have a Large Screw, that would be a 30PICT-3 or it's derivative, the H30/31PICT. (or a 34PICT-3 if you have a later engine) In all of these the big screw basically lets air past the throttle butterfly (which in such carbs, needs to be set so that it is SHUT when the choke is backed off) and functions as the idle speed setting. The smaller screw affects "some" of the idle mixture enough so to allow for emissions adjustments.

hale6968 Tue Mar 16, 2021 5:29 pm

Thanks to both. Yes I screwed it up. It is on the left of drivers side of my 34Pict 1. Thanks for the help.

glutamodo Tue Mar 16, 2021 11:42 pm

Hah, well there is no such thing as a 34PICT1.

The German Carburetor Company (DVG) made the following carburetors for VW:

28 PCI
28 PICT-1
28 PICT-2 (non-USA 1200 model)
30 PICT-1
30 PICT-2
30 PICT-3 (1970 USA 1600 SP version type 1 and type 2)
30 PICT-3 revised (non USA 1200 type 1 model)
34 PICT-3
34 PICT-4

Now most of these had variations. Starting in the 28PICT-1 range "modification state numbers" appeared on carbs, these denoted specific build spec applications. And VW had a LOT of them.

In the aftermarket, you get all kinds of naming on carburetors. H30/31PICT is one bastard-child carb that is fairly common.

Now, I have long wished someone would make a 34PICT-1, that is , a 34 series carburetor that was built like the 30PICT-1, the last simple carburetor that DVG made for VW before they started mucking about with emissions.

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