I have used the AFB series and they are best suited for putting around I will not even think about running one any more. I own and have Carter AVS {good carb} TQ good when worked on Q jet Good when worked on. Holleys in 600DP -650DP 750DP and 800DP and 650 DP spread bore. 600-650-750 vac secondary. I have run them all and settled into the 650DP and 750 DP and for winter the street avenger 750. The AFB is one of all tested and used to never run as good as holley or the other's for that matter