Holley carb question......

[xjs3667]

I got a holley 4160   and wondering how to convert it over to a dual feed line, I've been told it can be done, but can't find anything with all the extensive research I dun did

and also how to change it over to mechanical secondaries?    Just run a linkage from primaries to secondaries? 

I'd like to have the primaries open around 30-35 degrees before secondaries kick in so I'm thinking if I just run a linkage I can bend or adjust length as needed to get the secondaries to open when I want.     

Its been a while since I messed around with a carb    

[4x4xdodgeman]

you just need float bowls that are from dual feed carb.  you can't change that carb to mechanical secondaries. you can change the spring in the secondaries so it opens faster.