We developed the Direct Linkage System due to the complexity and availability of the factory 140 linkage. All 4 TBIs need to open at the same time and angle, so the direct link was developed to be an inexpensive and simple solution. The secondary is modified with a linkage follower and a return spring. This accessory is included in all Four TBI kits at no extra charge.
Installation: The Primary and Secondary must be installed together as the throttle follower on the secondary will not clear the primary linkage if installed individually. After installing the TBI, ensure the Primary TBI throttle is “bottomed out” with the throttle plate completely closed. The return spring should have enough force to auto adjust to the primary and the secondary TBI throttle plate should also be completely closed. Using a long 3/32 hex head wrench, tighten the Direct 4 Linkage “allen” screw and the linkage/TBIs should move easily without any restriction or binding
Do not remove the return springs on the secondaries in order to maintain precise angles at all times.