My point was that if someone measure on a Holley 4160 or 4150, they will find that the venturis have a different size between the primary and secondary bores, while the trottle plates and bores below have the same size. On almost all of them. The primary venturis are a little smaller than the secondary ones, and the primary jets are a little smaller on the primary's too. But this does not mean it is a spreadbore. Holley has a spread bore, the 4175 series. Well, these are the old types, I have no idea about newer stuff. Some people mix the term trottle bore with venturi, and sometimes those who are not so familiar with the Holley's find that oh, this carb has different size venturis maybe it is a spread bore. So it was just to clarify that so no one walks in a trap.