The Edelbrock #1901 AV2 Series 500 cfm Carburetor is designed and calibrated for small cubic-inch single carb applications, match with an Edelbrock Performer or Performer EPS manifold or other brands of similar design. Includes both timed and full vacuum ports for ignition advance. #1901 is calibrated for single-quad applications and factory equipped with: Metering Jets - Primary .095, Secondary .095, Primary Rod .070 x .052, orange spring (5' Hg). Use carb Studs #8008 or #8024 if needed. Match with an Edelbrock intake manifold for the ultimate induction upgrade.