[Dick Boneske]

With the cam you have, mods have to be made to the venturi cluster and power valve spring. Until this is done, idle will be too rich.

I have no idea what hole size a Holley #74 jet has, but with a carb that has 1 3/8" venturi''s vs. the standard '66 canter carb with 1.3/16" will need larger jets. I would start with .065".

Are you aware there are many Rochester 2 bbl. carbs larger than 1 3/16"? Why not find one of those and have someone tweak the venturi cluster and power valve to give you decent idle without the rich condition?

Here is an end carb I modified with 1.415" venturi's, larger than the stock 1.310' for the end carbs. This is as large as can be done with the end carbs. You can do the same for a center carb.