Webber Transition Ports

[Rick Parker]

If you are totaly exposing the first hole to gain an idle, your jetting is to lean. Your idle should only slightly uncover the first hole.

[tjyak50]

On a DCOE the progression inspection cover is just upstream of the idle mixture screw and under there are various progression port configurations depending on the model.

Off to the side is another cover but that is for the starting circuit.

[Gaz64]

In John Passini's book on Weber theory, he mentions chamfering the bottom of the throttle plate if progression is late.

[tjyak50]

Feedback.
I put the carbs in a CNC mill and had the boys drill the 4th hole (closer to engine and directly over the butterfly). .030" hole about .030" downstream of the old hole.

Car ran extremely rich.

Then I plugged the old "1st" hole and it runs like a dream now.
No leaning out on part throttle, no spitting or sneezing.

Its about 115f here in Phoenix today and my extra layer of thermal blanket even kept the carbs from boiling. (Z motor carbs sit ON the exhaust - stupid).

So far my experience with adding the 4th hole is good.
FYI>
TJ