Problem solved? Kinda

This may get confusing. 

Tis the nature of the DCOE

So I had a lean pop at the transition between the idle jets and main jets

Anytime you'd power on the throttle, VS roll on the throttle, the carbs would backfire

After a bit of research I decided a change in the accelerator check valve was needed

The accelerator pump itself can be altered to tune the lean spot out... 

...but a former Weber employee disapproved

You only need one check valve per carb

They are easy to take out, but the location makes them a pain to install

See item 12

Old accelerator pump check valves were 55s (.55mm bypass hole)

Changed to 35s (.35mm bypass hole)

Lean pop during transition pretty much disappears

Middle carb is still popping a little tiny bit

I think I know why

Much improved and good enough for now

PART 2

So the Z runs pig rich at idle, 500rpm

Tried messing with the fuel pressure

No luck

Went from 60F9 to 55F9 on the idle jets

No luck

Messed with idle speed

No luck

What was the next logical step?

Even smaller idle jets

Package from Italia

Ohhh shiny idle jets

50F9

Scared him

New Jets in the stack

So started it up and still runs pig rich

DAMN!

Switched back to 55F9s

I've realized due to my high duration cam the engine does not pull enough vacuum @ idle

Therefore the fuel has trouble atomizing and burning completely

Out the exhaust it goes

I'm not sure if there is anything I personally can do about it

I may have to take a trip back out to Rebello to see if they can get it sorted

On a side note with the smaller jets the lean pop was horrible on transition

maybe I will go to 0s (no bypass hole) on the accelerator pump check valve

This will basically not allow any fuel to be put back in the float bowl during the transitional period

That should eliminate the lean pop completely

If not I've got bigger problems