It won't...the linkage that actuates the secondaries can be bent/adjusted. This is explained in Cliff's book. Mine only opened up to about 45 degrees. After I adjusted the linkage(bending)to get the full 90 degrees, there was a noticeable difference in throttle response. As stated before in this thread, depending on the model of car they were installed on the secondary linkages were limited due to emissions regulations yada yada...I'd find another carb rebuilder.