Dual quads versus big hammer!!!...

j par said

The vacuum has everything to do with idle and the step up spring. You want the idle vacuum to override the step up spring and hold the rod down in the fatter setting. When you give it gas and the vacuum drops it allows the spring to take over and push the ride up to the narrower setting on the metering rod and allow more fuel. So the primary Jets and the fatter setting on the metering rod have everything to do with idle as I understand it..

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Ok, I see what you are saying. I wish I had one here to look at.

Essentially, when discussing the metering rods/springs we are talking the power enrichment circuit, which is the same as the power valve circuit for a Holley. They function the same.

That's why I asked about cruise vacuum. You should be able to pull the main jets completely out and it shouldn't affect idle.

If you are using springs based on idle vacuum, a big portion of the lean spot you are seeing in transition my be from the metering rods coming out of the jet too late. Especially with a stick you see a bigger hole right there. You can cover it up with the pump shot, but that means you may be using more fuel earlier in the pump stroke than you need.

Obviously I don't think this has anything to do with the air valve doors opening or not opening. But I think I has something to do with the lean spot you are seeing when you mash on it a bit.