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.