[olddog]

Priobe -- I owned one FE in my life and never owned or worked on webbers. So an expert I am not. I don't think you are trying to argue, but you want it explained to your satifaction. I will make a stab at it.

As durration goes up, the piston shoves air back out the intake valve on the compression stroke at lower rpms, thus the cylinder is less full and the engine makes less torque, at low rpm. This does allow the cylinder to fill better at high rpm, when there is less time to get the air into the cylinder. So big durration cams, cause the engine to make more torque at high rpm and less torque at low rpm. The more the durration, the more radically lopsided the torque curve gets. Actually the torque curve starts to look more like a picture of a volcano, when durration gets very high.

With a sigle carb and a common plenumb, a high durration cam, at idle, is pushing air and exhaust back up into the intake manifold causing instability. This instability causes cylinders to fill differently giving the lumppy idle. Webbers tame down the idle because each cylinder is connected to an independent pipe. There is simply less instability with the webbers, as no cylinder impacts the others.

What people are trying to say is that you are putting in a cam that will make its peak torque well above the rpm that your webbers will be able to supply the necessary CFM to make that torque. Therefore you will not see the high rpm torque that the cam could make, and you will loose all your low rpm torque. This is what I call a loose loose situation.

All this seems to be driven by the fact that you want a lumpy idle that the webbers, by there very nature, will not allow. If you are willing to have less power and an ill manored engine just to get a radical sounding idle and the look of the webbers, then go for it, but don't get mad when my small block zooms by.