Setting Idle SpeedThe problem with a long-duration camshaft with lots of overlap is low manifold vacuum that requires more throttle opening to set the proper idle speed. (C) Idle well: Fuel from this well travels to the top of the metering block, then turns 180 degrees and mixes with air from the idle air-bleed into the circuit. Note that there are two corresponding “flats” machined into both the nut and the needle & seat. 6-504 85R8515K & 85R8515K-2 “D” .097 Viton Adj. Copyright © 2017 VintageMusclecarparts.com This is normally the outlet port for vacuum advance. $55.36 Ships directly from the manufacturer in 24hrs Lowest Price Guarantee. Holley carburetors have powered every NASCAR® Cup team and nearly every NHRA® Pro–Stock champion for four decades. That translates pretty close to 3/16, 5/16, and 1/16, which it what's listed for the 008. All these components work together to create the fuel curve that helps make horsepower. Another selection tip is to undersize the carburetor slightly. Holley has been the undisputed leader in fuel systems for over 100 years. The key to a properly designed performance carburetor is to move fuel out of the booster as efficiently as possible while creating the proper air/fuel ratio as the engine runs through its rpm band from just past idle to redline on the tach. Available in different sizes, they're also available in different materials to suit a wide range of applications. From propelling the LS-, Coyote-, and Gen 3 Hemi-swap trends, to continuously innovating late-model and vintage vehicle performance, Holley’s commitment to its customers and their cars is at the core of everything we do. Available in different sizes, they're also available in different materials to suit a wide range of applications. By using screw-in idle air-bleeds in the top of the carburetor, you can adjust how quickly the idle circuit responds to changes. One problem we run into is carburetors that have been re-manufactured, or customized. Bowl Side of Metering Block(A) Timed spark port: This outlet supplies ported manifold vacuum for distributor vacuum advance only after the throttle is opened slightly. (C) Primary throttle blades: All air flows through these blades at part throttle up to a given percentage of throttle opening. Package: 0.4 x 4.35x 3.9 cm per 3.9 Kg, Replace genuine Mikuni. 3 0 obj Emulsion ImmersionYou'll see references here to emulsion circuits, an important-sounding term that describes mixing fuel with air. This is a great advantage for car crafters because if you're armed with the basics on one carb, that knowledge will carry you through all the different variations. Circuits There are more pathways for fuel through the carburetor than just the main metering circuit, so this is your opportunity to become the neighborhood Holley guru. Holley Needle & Seat tips. This valve determines when additional fuel is added to the main circuit. Holley carburetors have powered every NASCAR® Cup team and nearly every NHRA® Pro–Stock champion for four decades. With low-boost combinations under 10 psi, a stock Holley needle-and-seat assembly is sufficient. The original HP carbs are available in sizes ranging from 390 to 1,000 cfm in the 4150 configuration. Combining the main jet flow area with the area of these emulsion holes and the high-speed air-bleed (along with a raft of other minor inputs) creates the basic fuel curve.