clifford adapter =added venturi?

[Anonymous]

Okay after that long convoluted topic- there simply was a lot of real time venturi effect (gauge on going down the road) from the advance port of my 2BBl autolite-- then :idea: i have a 2bbl to 1 bbl adapter. This is a funnel or venturi shape; how much added velocity is this giving to the fuel from the bottom of the carb to the intake in that aprox. 2" space. Is this contributeing greatly to the venturi effect i am seeing on the vac gauge, The interior end of the port or vac source of the advance port is right at the throttle plate area which has me convinced it is going to see a little venturi effect but i am seeing a lot. Next it flows through the adapter which has the same basic shape of a venturi also- So maybe the adapter is causeing my adv. port to become much more venturi affected.

 

[rbohm]

8) very possible that is whats happening. anytime you narrow an opening, you get the venturi effect.

 

[Anonymous]

is that an Ace Venturi effect?


alrightythen

 

[Anonymous]

The adapter is not shaped like a true Venturi. But you will see a velocity increase through the reduced diameter. But the adapter has very little to do with your results.

There is a misconception regarding an engine operating at WOT. When the throttle plate opens wide, the engine /manifold vacuum will drop because it takes a second for the mass of air above the throttle plate to start moving into the cylinders. Basicallly, the volume of air has just been allowed to expand into another volume, and the pressure equalized. But the engine/manifold vacuum does not stay at zero for the remainder of the rpm range. As the motor speed increases (with the plates wide open), the engine vacuum will still build up. The loss of vacuum signal is just a temporary thing until the engine speed increases.

Think of it this way. Those vacuum readings are nothing more than a difference in pressure between the air outside of the carb and the air in the manifold rushing in to fill the cylinder. If the engine / manifold vacuum remained at zero, then there would be no pressure difference between the air above the carb and the air in the manifold waiting to enter the cylinder. Therefore, the engine would not run, because there would be no pressure force driving the air into the cylinder as its volume is expanding. Vacuum tends to confuse some folks, because they think of it as negative pressure, when in fact it is just a "less positive" absolute pressure.
Hope this helps.
Doug