Did you take the advice on here and stay away from the Edelbrock? My professionally build 331 SBF came with a Thunder series AVS # 1806. By the time I ran the first go cart, I realized an issue. At first it idled fine, as time went on the idle failed and I have tried to adjust it many many times. I replaced the elec choke hat and re adjusted the float levels as they were off. Now it is a lucky day if it will idle at all.