The Vortex is normally used with a stock exhaust manifold. The "Hot Spot" plate is for heat transfer to maximize fuel vaporization, which vastly improves performance and tune-ability. The plate GETS PLENTY OF HEAT and is not drilled. Carburetor mounts are at 3.5 degree angle to keep the carbs level. There is one vacuum port. A fuel pump is not required. Unit will not fit to headers.

Model B carburetors do a fine job or try a pair of Tillotsons. The Model "A" Zeniths have a tendency to stall at quick stops, due to the float hinged to "dive" and flood carburetors used in pairs. The "B" Zenith do not stall in pairs. Tillotsons work well.

Parts: 22 Parts In The Kit

Vortex Specs: Intake ports 1.255 ID; Exit ports 1.375"; Front carb to back carb space 1.5"; Back carb to stock exhaust about 1"; hot spot flange not drilled; One vacuum 1/8" pipe plug provided; Carb mounts machined at 3.5 degree angle to level carburetors. Exit, throat to throat, port centers are 9.563" apart.

Carburetor Specs:

Model A Zenith: 4.3 pounds, Throttle Dia. 1.18";

Model B Zenith: 4.1 pounds, throttle Dia. 1.29";

Allstate: 2.7 pounds, Throttle Dia. 1.15";

Tillotson X: 2.3 pounds, Throttle Dia. 1.18".

Additional Applications: The Vortex could be used on any engine that has intake port center-line of 9.563" (+ -). The manifold CAN be turned over to make a dual down-draft and using Carter or Solex carburetors.

Generally speaking, when used as an updraft,  it is best to have up-draft carburetors BELOW the exhaust manifold to prevent fire. Adapters could be fashioned to accept a wide range of carburetors