good day ,
We are working on a beautiful 55 Mercury Montclair , that did have the Holley 4000 TEAPOT carb from the factory . 
That was replaced along with the 55 distributor in 1972 by a previous owner .
Holley 4160 with spacer on intake since 1972 and the front primaries do not open more than a third of the way .
of course vacuum secondary never opens . Previous owner did not drive this car very much , and I guess it ran good enough for him at the time .
The new owner and myself are looking to figure out why the oem linkage will not do the job of opening the primaries .
Was there a trick to this linkage ?? Special adjustments anywhere ???
It seems this was a very popular swap on the Y block back in the day .
thanks for the assist on this topic .