Setting up the 4bbl carburetor linkage

Weber linkage here

  • Wire the carburetor linkage fully open.
  • Install the cross-shaft onto the engine, keeping the shaft as parallel to the firewall as possible and fairly horizontal.
  • Install the link from the carb to the cross-shaft, adjusting the length so that  the cross-shaft bellcrank is angled about 30 degrees toward the firewall.
  • Adjust the bellcrank on the pedal shaft so that it is angled back toward the firewall about 20 degrees when the pedal is bottomed out on the floor.
  • Install the link from the pedal to the cross-shaft so that the pedal is about 1/2" from hitting the floor.
  • Remove the wire holding the carburetor linkage and check whether the pedal is at a convenient height.  If it is too high, change the link footbox link to a lower hole on the cross-shaft.  If it is too low, change the engine link to a lower hole on the cross-shaft.
  • Install the return springs and check whether you're still getting full throttle.
  • Tighten all bolts and jam nuts, check for interference, and grease all the pivot points.
  • If you want the "smooth look" shown below, cut some 5/16" brake line to length to cover the middle section of the threaded rods.
While most Holley carburetors are similar, small details can change how the linkage is set up.

The engine at right, with a low-rise manifold and 550 cfm carb uses all the top holes in the footbox bellcrank and linkage cross-shaft.

Note the dual return springs on both setups: One from the bottom of the carb to the manifold, one from the manifold to the cross-shaft bellcrank.

Low riser manifold

The layout of this high-rise manifold and 750 cfm carb looks the same, but the link from the footbox goes to the  lower hole in the cross-shaft bellcrank.  The link to the carb is in the top hole of the cross-shaft, giving more throw at the carb.

High riser manifold