Dual Weber IDF 40s, Carb Rookie question... Options

[malcolm2]

Hello everyone. I will preface by saying that this is an engine from a 914. (IMG:style_emoticons/default/piratenanner.gif)

But it is in my VW Bus. Just now getting it moving down the road. Everything is new.

Carbs are new and I am a carb rookie, as well. Bought them from Aircooled.net and had them cleaned and set-up for the bus. My 914 has L-Jet FI, this group has taught me enough about that system to be dangerous.

So here is my question for the carb experts. What should the Pump Valve spray look like? It seems erratic and drippy. It kicks in 1st as I open the throttle, not a spray but pore, really. I will say that I see that in all 4.

[Superhawk996]

Don’t worry about IDF specific book. I personally like the Dellorto book but it is now out of print.

The import part is understanding:

Weber IDFs run on the idle circuit and transition ports most
Of the time at light cruise and light tip in. You really only run on the mains when RPM is high and creating lots of vacuum at the Venturi neck. You can convince yourself of this truth by driving the car with the main jets and emulsion tubes removed.

As a result, the idle circuit tuning is critical. Note: Your motor isn’t idling well based on the video. Likewise it doesn’t transition off idle well.

You need to know what size Venturi and jets you’re working with as your baseline. You won’t get a decent snappy throttle response until you get down to 28mm venturis. Most
Carb kits come with venturis that are 30-32mm (too large) for top end HP - not good driveability.

Make sure your transition ports aren’t partially uncovered at idle. I used to see this all the time. Make sure your idle speed set screw isn’t holding the throttle blades too far open and uncovering the transition ports.

You need to balance airflow between each individual barrel before synching the carbs. Each time you adjust airflow - you’ll have to go back and tweek idle mix and also idle speed.

Look around for a used copy - Amazon, Ebay, post in forum, etc