The stock Webers from Mercuriser seem to be setup for a very specific engine/intake combination. Mine originally came with different sized jets in all four positions.

Edelbrock
 

Night,

To clarify my statement, what I noticed were that the primary butterfly blades on the primaries found on the Weber were the same size as the secondaries. The Edelbrock had smaller primaries than the secondaries. Other things that were resolved was that new Edelbrock resolved thehard starting after a long down time or when the engine was hot and had to hold the throttle open a bit to start. All resolved GREAT!

I switched from a set of vaccum secondary holleys to the Edelbrocks 1409. They ran great right out of the box and didn't have to tune them much. I wanted a simple carb that I didn't want to mess with much. IMO go with the Edelbrocks if you want to bolt on and go.