Very rich at cruising Weber 46

[Seppo]

3.2 engine stock, D21 camshaft, Dansk1 5/8" primaries headers
Weber 46
Main jet 150
Idle jet 50
Air corr 180
Emulsion F26
High secondary venturi

Idle AFR 13-13.5
WOT is 12-13.5

The cursing get really rich low 10 at very slight throttle 2000-3500RPM. If I step on a bit it come on the range 13..

The first emulsion tube was F3, it was worse, also step down to 50 idle jet from 55.

Any suggestion what to change?

[Tom_in_NH]

Floats set too high perhaps?

[1QuickS]

Idle air correction jet is .80 mm in 46mm Webers, if you change the size up then transition mixture will lean out. This is an easy modification, OEM idle air correction jets are not designed to be tunable.

Are these the "new" Webers? They have an early progression pattern developed for the 2.0 race engines. Later Weber 46s had a more street friendly progression pattern.

Also, you did not include main venturi size. A too small venturi size will advance when main circuit starts, cruising is typically an idle circuit operation. The switch from F3 to F26 shows that your engine likes a delayed initiation of the main circuit, F3s activate earlier than F26s.

Fuel pressure should be around 3.5 psi and it would be good to check float levels with the engine running. Needle valve quality is not what it used to be and you may either have high float levels (mentioned already) or poorly sealing needle valves.

[Seppo]

The main venturi is 36. This is a NOS Webers made in Italy.
Fuel pressure is checked 3.5psi,
The float level were 1 mm under the levels (2 lines) when the car is running.
I will check the Idle air correction jet size

[proporsche]

this might be silly Q ..do you have the fuel press regulator in the system like PMO?

Ivan

[Seppo]

The Idle air correction jets were 0.7 now I enlarge to 0,8mm.
Hopefully I can testdrive on the weekend

I have pressure regulator.

[1QuickS]

Be sure to perform Lean Best idle mixture screw adjustment before driving.

[Seppo]

Now The Idle air jet enlarged to 0,8mm and change back to F3 emulsion tube
Idle AFR is around 13.2
The slight throttle (cursing) now 11.

If the I open up throttle a bit more, it come up to 13....

Now thinking to enlarge the idle air more or change back to F26
Thank you Paul for the help!

The ignition timing are 8 at idle, 20 at 2000 , 31 at 3000, 32 at 6500

[1QuickS]

One is glad to be of service.

Congrats on your improving cruise AFR. Stay with F26 E-tubes and test before going larger on idle air correction jets.

[Seppo]

Changed to F26. It has improved the steady state cruising, but ruin the acceleration.

My plan now to put back the F3 emulsion tube and drill a 0.8mm hole on the arrow level. My idea is the richness caused by too much vacuum....

[1QuickS]

I like it, you can always solder it closed. Use the top hole location of the F26 as a height gauge.

[Seppo]

Drilled one 0,5mm hole and the AFR rised 11,2-11.3
I will drill another hole and hope it will be ok

[Seppo]

Now I drilled one more hole on the upper part of the F3 emulsion tube.
There are 2 x0,6mm whole, but at 2000RPM still the AFR 11.4 at light cruising at 50MPH

Meantime my friend build a 6 channel wideband WBO2 measurement tool for me.
It work gerat and I can monitor left and right side.

[1QuickS]

At 2000 RPM and cruising you are on the idle/progression circuit, not even close to main circuit activation.

Increasing size of idle air correction jets from 0.80 (OEM) to 0.90 or even 1.00 will lean out cruise. I can supply a modification kit for this or provide detailed info for you to modify yourself.

Contact me via my email:

info@PerformanceOriented.com