Edelbrock 800 AVS - Runs Lean in Cold Weather

[Dusterndart340]

I hope someone here has some experince with this issue. Here is my set-up-

340 stroked to 418
10.2 true compression (Ross Dish Pistons)
Cam: Comp Extrem Energy 274H (230/236 - .488/.491)
X-Heads - Some bowl work - 69cc's
Exhaust is HP Manifolds with 2 1/2" TTI "H" Pipe
Performer RPM Intake
Timing: Initial @ 16 BTDC - Total 32 all in at 1600 RPM
Vacuum: 12 to 13 @ 900 RPM (No Vacuum Advance)

The car ran great this summer with the following Jets & Rods.
Primary - .113
Secondary - .107
Meetering Rods: .068 x .047
Orange Springs:

This combination is the stock out of the box configuration. It ran a little rich at idle (13.5 AFR) and (12.5 AFR) under hard acceleration. For a mild build it was very satisfactory.

The Problem:
The weather turned cold and it runs over 20 AFR at idle with the above configuration. It surges at crusing RPM (2500 to 3000) and runs at 20 or above AFR. I have changed the primary jets to .116 and rods to .068 x .057with Silver Springs and it has helped at idle (Idle Screws are 4.5 turns out) but it still surges at cruise speed.

I have checked for vacuum leaks around the carburetor base and intake manifold runners but don't find anything. This problem has to be something other than colder weather but I can't seem to figure it out.

Any other ideas or suggestions?

 

[ir3333]

...no authority but is not getting enough gas...
..dirt in carb, plugged fuel filter filter,stuck float?

 

[Dusterndart340]

You might be right about the fuel filter; I haven't changed it and will give it a try.

Thanks-

 

[Dusterndart340]

Found and fixed the problem:

I removed the electric choke mechanism last summer as I never had it hooked up. To change jets you must disconnect the choke linkage (2 places) to remove the top of the carburetor; it makes it much quicker with the choke removed.

The electric choke has a "choke piston" port that connects to the base of the carburetor and therein lies my vacuum leak. I had no idea the electric choke had a port to the carb base; a simple plug has solved my problem and the Dart is running fine again.