Owners manual

ManualsBrandsHolley Performance ManualsAutomotive0-4781C Double Pumper Carburetor

PERFORMANCE CARBURETOR

INSTALLATION AND ADJUSTMENT INSTRUCTIONS

Read instructions thoroughly before, during, and after installation.

NOTE: This carburetor is for use on Motor Vehicle Applications Only!

Universal Double Pumper (650, 700, 750, and 800 CFM)

Holley Performance Products cannot and will not be responsible for any alleged or actual engine or other damage, or other conditions resulting

from misapplication of the products described herein. However, it is our intent to provide the best possible products for our customer; products

that perform properly and satisfy your expectations. Should you need information or parts assistance, please contact our Technical Service

Department at 1-270-781-9741, Monday through Friday, 7 a.m. to 5 p.m. CST. Please have the part number of the product you purchased on

hand when you call.

This carburetor has been specifically calibrated for peak performance at the racetrack. NOTE: This carburetor is not a street oriented

calibration and does not have the capability of meeting Federal or California exhaust emissions standards. In addition, this calibration will

provide less than optimum driveability and fuel economy if it misapplied and used on late model street engines, which operate at high

temperatures.

Many people mistakenly believe that they will realize performance and economy gains by using a “non-emissions” carburetor on an emissions

oriented engine. This is simply untrue. The requirements for reduced exhaust emissions on all late model vehicles have stimulated increased

carburetor development. Research and development efforts have resulted in carburetors, which feature the same “full power” fuel calibration as

carburetors of the muscle car era and yet deliver improvements in fuel economy and reduction of exhaust emissions levels. Late model

“emissions” carburetors do not contain “secret emissions controls”. They simply provide the various timing mechanisms, which can trigger other

emissions control devices. Regardless of the condition of your emissions control systems, best fuel economy gains will probably be realized by

using the Holley Emissions Design/Street Performance carburetor recommended for your vehicle.

WARNING: This carburetor is NOT designed for use with any automatic overdrive transmissions. If used on an automatic overdrive vehicle,

severe transmission damage WILL result.

NOTE: Due to the absence of a transmission kickdown lever, this carburetor should not be used on Ford applications equipped with an

automatic transmission.

INSTALLATION INSTRUCTIONS

Since this carburetor is intended for racing applications, and since such applications often differ greatly, these instructions are very generalized.

It is assumed that the person making the carburetor installation has basic automotive skills and experience.

This carburetor is not a “direct, bolt-on” (i.e. custom linkage pieces may be required on “off-road” engine packages).

1. Remove the air cleaner.

2. Disconnect the throttle linkage and throttle return spring.

3. Disconnect the vacuum advance hose (to distributor), PCV hose, and fuel line.

4. Remove the carburetor from the intake manifold.

5. Remove the existing carburetor flange gasket on the intake manifold. Use a gasket scraper to assure that no small particles of the old

gasket remain. Make sure that no pieces of the old gasket material fall into the manifold. NOTE: Cover the manifold opening while

cleaning the carburetor flange.

6. If a different manifold is to be installed, the following should be considered:

A. Run a cleanup tap into each manifold bolt hole in the cylinder heads. This will remove any foreign deposits and enable even torquing

of the manifold bolts. Chances of manifold vacuum leaks resulting from manifold warpage will be minimized by this extra attention.

B. Coat each side of the intake manifold gaskets with a good silicone based sealant.

C. If cylinder heads are being milled to increase compression, remember to mill the manifold head surface to assure proper port

matching and sealing.

7. Install the throttle ball in the appropriate position on the throttle lever (Fig. 1). Some Chrysler applications may require a Chrysler throttle

lever extension (Holley P/N 20-7) and Chrysler throttle linkage stud (20-67). These are installed in Fig. 2.

Summary of content (6 pages)

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PERFORMANCE CARBURETOR INSTALLATION AND ADJUSTMENT INSTRUCTIONS Read instructions thoroughly before, during, and after installation. NOTE: This carburetor is for use on Motor Vehicle Applications Only! Universal Double Pumper (650, 700, 750, and 800 CFM) Holley Performance Products cannot and will not be responsible for any alleged or actual engine or other damage, or other conditions resulting from misapplication of the products described herein.
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8. If the vehicle requires other linkage hardware, such as automatic kickdown linkage stud, remove the stud from the original carburetor and install it in the appropriate place on the throttle lever. 9. Install the carburetor flange gasket on the intake manifold. Figure 1 Figure 2 10. Place the carburetor on the manifold. Open the throttle and check to assure that the throttle plates do not interfere in any way with the manifold.
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Figure 3 13. Reconnect the appropriate vacuum hoses noting the correct fitting from Figures 1,3, and 4. A. Plug any vacuum source not used. B. The “timed spark” fitting does not provide vacuum for distributor advance at idle. Vacuum for advance is available as soon as the throttle is opened from idle and the engine is placed under a load, such as acceleration or cruise.
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NOTE: It is essential that a quality inline fuel filter be installed between the fuel pump and the carburetor. Figure 5 15. Install a suitable manual choke cable, such as Holley P/N 45-228 and choke mounting bracket P/N 45-229. Check to make sure that the choke fully opens with the cable. 16. Start the engine and check the fuel line and inlet fittings for possible leaks. At this time, recheck to assure all existing vacuum hoses are attached properly. Plug any fittings that are not used. 17.
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Figure 7 GENERAL INFORMATION: A. FUEL PRESSURE: This carburetor has been designed to work best at fuel pressures between 5 and 7 psi. Holley recommends 7 psi at idle, and a minimum 4 psi at engine redline. Three 8” fuel lines can result in adequate (indicated) fuel pressures, but restricted fuel flow. Use of a Holley electric fuel pump at the rear of the vehicle next to the fuel tank assures adequate fuel pressure under even the most severe operating conditions. B. ADJUSTMENTS: 1.
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Figure 8 C. MAINTENANCE: WARNING: Fuel systems components, which are required to operate under severe conditions, such as high underhood temperatures should be periodically inspected to assure no fuel leakage and the soundness of hoses. High temperatures promote faster aging of nonmetallic materials. Hoses that exhibit surface cracks when bent 180°, should be replaced.