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I'm asking this to see if Others have the same issue with their Weber carbs. I find that when it is cold and very damp as in foggy or raining that my engine idles rough and stalls after the choke comes off. In dry weather I have no issues. Am I alone here or do others have similar issues?
This is one of the drawbacks from eliminating the factory air cleaner and riser from the exhaust manifold. Although cold air is ideal for an engine intake, the moisture can suppress combustion. With the factory set up pulling a partially heated air charge from the riser it can counteract it a little. Try using premium fuel and re-tune the ignition to be a bit more aggressive (another thing to take note of is the increased vacuum the Weber creates - it causes the stock distributor to over-advance timing so low down power is always a bit off. You either compromise the timing to get it running decent where you can, or get the distributor modded to match the overall timing curve for the Weber)
Perhaps I'll try letting it warm up a bit longer before tapping the accelerator to kick down the high idle. One other thing I've noticed is if I shut it off for a few minutes then restart it is fine. I ask this because sometimes I can drive 20 miles and when I stop it will falter and stall. If I pull over and wait a minute before restarting it idles fine. I was wondering if these carbs are known for vapour locking.
There might be an issue with the electric choke (?). I would've thought there'd be an issue during hot weather :shrug:
When it is dry weather, freezing cold or stinking hot, there are no issues. A little above freezing and really damp, is when it acts up. I have two trucks and both have Weber carbs. It's the same scenario with both. I think you might be right in that the stock intake with the heat riser dries out and warms the air being drawn in until the engine warms up. My problem might be limited to certain geographical areas where it gets cold enough.