Hi, I have a 770 street avenger on my mildly built 429 in my 77 F150. The motor has a mild cam (summit brand, not sure how much lift) Edelbrock performer intake, 9.0:1 compression, L&L headers with 1 3/4 primary tubes, and Flowmaster 2.5 inch dual exhaust. My trouble is, when I let out the clutch, there is a momentary stumble on takeoff that makes it difficult to get going. This has become a major aggravation and I am not sure where to look for the problem. It also smells very rich like gas all of the time. I had a local mechanic adjust it for me, but it came back worse than when it left! Can anyone tell me what I need?

 

Just taking a stab at it - I never have used one of those carbs before - I like the quadrajet, and thus, I had a similar problem once with the vacuum secondary spring tension not being tight enough... Once I stiffened up the vacuum secondary spring tension, the stumble immediately disappeared. The smell of raw fuel means it's running rich, also could be part of the problem...

Here are a couple of basic online carb tuning guides to help you dial in the screws..

1. Setting Idle Mixture The Right Way
2. How to Use and Interpret a Vacuum Gauge