Resurrecting an old thread with an UPDATE. I was given a Holley 3310-2 (750 cfm) so I decided to try the 3 bbl setup again. I bought another conversion kit from Tom and installed it along with a Quick Fuel adjustable vacuum secondary diaphragm, and a Proform secondary conversion plate (to make it like a 4150 with adjustable jets). I did a lot of tweaking on the idle restrictions, air bleeds, main jets, etc. and learned a lot about Holleys. The only thing that is still black magic is how the emulsion jets work but I have a Proform primary metering plate with a 4 circuit emulsion setup to try in the future.
This configuration is running really well. The low end is much cleaner that with the 4 bbl 600 cfm carb. Secondary actuation is easy to tune-I ended up with a black (stiffest spring) and the adjustable diaphragm turned in most of the way in to slow it down enough. I'm very happy with the results and glad I gave it another try.
