I have a holley avenger 670 and its on my 305 with longtube headers and proflow air cleaner I want to tune it for better acceleration but i dont have the instructions and the holley tech line isnt really helping me so I want to know how to adjust the secondarys it says no trouble adjustable vacuum secondary so do i have to adjust one of the screws or change springs? The only screw on the carb that i know what it is- is the idle screw. i want better acceleration i cant even break the tires loose when i punch it i also dont have the vacuum advance hooked up on the distributer thats problay not helping acceleration. So what do i have to do????

 

you cant spin the tires when you punch it because u have an engine that is throwing its bottom end out of the exhaust.


what cam are you running??? you have the same exhuast capability as my 430hp 350 lol.. .

to answer your question, the secondaries can be adjusted by removing the black cover with two screws that sits on the PS of the carb, closest to the distributor. buy the psring kit from holley, it comes with an assortment. your going to want to use a yellow, a trimmed yellow, or white spring to give you the most give on the secondaries... i ran a trimmed up yellow on my 305 when i ran the same carb....

You could play with accelerator pump cams, but the stock one is more than engoh for a 305

 

Yea i figured i have to change the springs. I have a stock cam right this second but have a cam that im going to put in when i get an intake and some aluminum vette heads.