Avenger 870

[69customS]

I have an 870 and brand new install crate engine. 400 Pontiac stroked to 455, Crane cam, KRE heads. At idle engine produces roughly 6-8" vacuum. This carb has been a challenge to say the least from the get go. First, ran very rich at start, plugs were soaking wet...rejet from 82 down to 78, problem solved. Second problem, when driving car, it runs on as if on cruise control. Also, at normal start (acceleration) from stop the engine stumbles hesitates like it is not getting enough fuel. I changed both power valves - front was 4.5, rear was 3.5, changed them both to 2.5. That problem is just about gone...but the run on persists. I have to kick the throttle to get it off this run on sensation. The choke has been adjusted clockwise and counterclockwise, and yes it works as it should. Any thoughts on this would be great!
Jim

[Danny Cabral]

Check this:
Adjust the primary throttle blades (idle speed screw) to expose no more than .025"-.030" of the idle transfer slots.
They're located under the primary throttle blades - must remove carburetor to measure with wire. Common problem.
If so, you'll need to open the secondary blades a little bit, in order to close the primary blades (to maintain desired idle speed).
When the idle transfer slots are exposed too much, it renders the idle mixture screws useless.
http://www.youtube.com/playlist?list=PL353239D6A7D7BFF0 (Watch video titled "How To Adjust The Secondary Speed Screw".)