[Power Surge]

Originally Posted by MrMagoo

Thanks Sal. I didn't know about the new needles and seats. Is there an optimal pressure? is 8 better than 6.5 on a carb that can handle it?

I'm going to dig out that book, I don't want to misquote it, but I believe the author was stating that there is positive atmospheric pressure in the world inside the air filter created by the air rushing down into the manifold. Something about the Venturi Effect.

It's dependant on your needs. Most street driven carbed cars don't need 8 psi, but it's also not going to hurt anything as long as it doesn't blow the floats open. I run 4-5 psi on my car, but I'm also not making 600hp either.

One thing to keep in mind, is that bowl level height and fuel pressure changes will affect your tuning.

As for the pressure thing, positive pressure does occur, but that's down in the venturi by the boosters, and doesn't have anything to do with the vent tubes up top.