Dual carb question, Dellorto 40s on a 1.8L to be exact Options

[terrymason]

The problem - The car will go very lean around 2500 rpm, as if the pump jets were too small.

History:
New fuel pump (3.5 PSI to each carb)
55 idle jets
55 pump jets
140 main jets
175 air correctors
These carbs are new to the car, and I'm trying to dial them in.

The car is lean when I first start it (16 / 17 on my air / fuel gauge), but then levels out to a nice 14.7 idle when warmed up. While driving, I can give the car 20% or so of the pedal, and drive up to highway speeds nicely, but when I goose it, it will go very lean (18-22 on my gauge) followed by a series of backfires and loss of power. I started off with 35 pump jets, and have moved up to 55s, which appear to be the most popular around here. I've also adjusted the pump jet linkage, from the nut fully loosened, and moved it in as far as it would go before affecting the main throttle shaft (like 60 turns or something).

What do you guys think, do I need 75 pump jets?

[Twystd1]

I just went through this with some other 914 bretheren.

You will NEVER get the carbs dialed in right with an 009 distributor.

Unless you have the 009 dialed in and curved PERFECTLY for a type IV engine. And I don't care if you have a crane, points or Pertronix in it.

Nobody believes me until they stick in an stock type IV or Mallory distributor.
Then re-dial in the carbs and the engine runs right for the first time.

Many companys sell a 009 dizzy supposedly setup for the type IV engine.
So far... In my experience.... It's total bullshit.
I have yet to see a 009 from any company that is correctly curved for a type IV engine. They suck... Toss it. A used bone stock dizzy is better.
And you won't be tuning your carbs around a screwed up ignition curve and inaccurate dwell.

Try it... You will like it.

I gave my last three stock dizzys away just to prove it. As these three guys had the much of the same carb tuning problems. Once the correct ignition curve was there for the type IV. The tuning issues were much easier to fix.

That is my experience. Yours may well be different.

Regards,

Clayton


PS: I hate 009 They are a bane to the 914 society. There ought to be a law against em in the type IV world. That goes for progressive webers as well.