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]

I wouldn’t judge by that 1.3mm variance in the amount of screw showing. You have casting variance, stamped linkage variance, and variance in the length of the screw. That 1.3mm variance is sort of normal when you synch carb to carb.

Especially since you seem to be happy that it’s running better and improving.

I’d just stay focused on trying to lean out idle mixture and given where you are in the process, I’d just swap the idle jet and keep moving forward.

I’ve always made a point of being sure that the transition ports are closed when it is on the bench for initial bench settings. It’s much harder to do when the carbs are installed.

What I’d probably do is shine a light down the throttle bore and verify that the throttle butterfly is hardly open when it’s setting at rest on the idle speed screw stop. Throttle butterfly plates should basically be closed with only a tiny sliver of a gap. Maybe you might be able to see the top of one of the transition ports sitting ABOVE the plate that would be good. If the butterfly plates seem to be lifted significantly when sitting in the stops, I might pull them and bench check where they are sitting. Just pulling them and replacing them won’t mess up too much of the tuning you’ve done but you’ll have to verify and then re synch again.

I would really hate for you to pull them again which is why I’m suggesting you go down in idle jet 1st. It’s easier and is probably going to be more of a sure thing vs the chance that the transition port is uncovered at idle.