Holley 0-80508S 750 CFM Classic Holley Carburetor User Manual

Product Overview

The Holley 0-80508S is a 750 CFM Classic Holley Carburetor designed for performance and drivability. It features dual feed fuel inlets for consistent fuel delivery and vacuum secondaries for smooth operation across a wide range of vehicles. This carburetor is equipped with an electric choke for easy startups and is 100% wet-flow tested and street calibrated to ensure optimal performance right out of the box.

Key features include:

• Vibratory polished finish for enhanced aesthetics.
• Performance upgrade suitable for stock to mildly modified vehicles.
• Universal calibration for straightforward bolt-on installation.
• Factory preset electric choke for reliable cold starts.
• Vacuum secondaries that adapt to vehicle weight, gearing, and transmissions for smooth secondary opening.

Figure 1: The Holley 0-80508S 750 CFM Classic Holley Carburetor, showcasing its polished finish and overall design.

Installation and Setup

Proper installation is crucial for the optimal performance of your Holley carburetor. This carburetor is designed for universal fit and easy bolt-on performance, but professional installation is recommended for best results.

Safety Information

WARNING: This product is not for sale in California on pollution controlled motor vehicles. For California residents, please be aware of Proposition 65 warning: Cancer and Reproductive Harm - www.P65Warnings.ca.gov.

Pre-Installation Steps

1. Ensure the engine is cool and the battery is disconnected.
2. Carefully remove the old carburetor, if applicable, and clean the mounting surface on the intake manifold.
3. Inspect the intake manifold for any debris or obstructions.

Mounting the Carburetor

The Holley 0-80508S comes with necessary gaskets for installation. Use the provided square gasket for the main mounting surface and the round O-ring for the fuel inlet connection, if applicable.

Figure 2: The Holley carburetor packaged with its essential installation components, including mounting gaskets and electrical wire for the choke.

Figure 3: Close-up of the square mounting gasket, designed to create a seal between the carburetor and the intake manifold.

Figure 4: The round O-ring gasket, typically used for sealing fuel line connections or other circular ports on the carburetor.

1. Place the square mounting gasket onto the intake manifold studs.
2. Carefully lower the carburetor onto the studs, ensuring it seats properly on the gasket.
3. Install the mounting nuts and tighten them evenly in a crisscross pattern to the manufacturer's recommended torque specifications.

Connecting Fuel and Electrical Lines

The carburetor features dual feed fuel inlets for robust fuel supply. Connect your fuel lines securely to these inlets. The electric choke requires an electrical connection for proper operation.

Figure 5: Side view of the carburetor highlighting the electric choke mechanism, which aids in cold starting.

Figure 6: Front view of the carburetor, clearly showing the dual feed fuel inlets designed for high-volume fuel delivery.

1. Connect the main fuel line(s) to the carburetor's dual feed inlets. Ensure all connections are tight to prevent leaks.
2. Connect the electric choke wire to a switched 12-volt ignition source. Refer to your vehicle's wiring diagram for the appropriate connection point.
3. Connect the throttle linkage and, if applicable, the transmission kickdown linkage. The carburetor is designed with a Ford A/T kickdown provision.

Operating Instructions

The Holley 0-80508S carburetor is designed for superior performance and drivability. It is 100% wet-flow tested and street calibrated from the factory, meaning it should operate efficiently with minimal initial adjustments.

Starting the Engine

1. With the electric choke connected, turn the ignition key to the "ON" position for a few seconds to allow the fuel pump to prime the carburetor.
2. For cold starts, depress the accelerator pedal once to set the choke.
3. Turn the ignition key to "START". The electric choke will automatically adjust the air-fuel mixture for cold engine operation.
4. Once the engine starts, allow it to warm up. The choke will gradually open as the engine temperature rises, reducing the idle speed to normal operating levels.

Driving Performance

The vacuum secondaries on this carburetor are designed to open smoothly and progressively based on engine load and vacuum. This feature ensures optimal fuel delivery and power when needed, while maintaining efficiency during normal driving conditions. The carburetor automatically compensates for various vehicle weights, gearing, and transmissions.

Figure 7: Another side view of the carburetor, illustrating its robust construction and various adjustment points.

Figure 8: Rear view of the carburetor, showing the vacuum secondary mechanism which opens based on engine demand for increased airflow and power.

Maintenance

Regular maintenance ensures the longevity and consistent performance of your Holley carburetor. While the carburetor is built with all-metal parts for durability, periodic inspection and cleaning are recommended.

• Fuel Filter: Regularly check and replace your fuel filter to prevent contaminants from reaching the carburetor. A clogged fuel filter can lead to poor performance.
• Air Filter: Ensure your engine's air filter is clean and unobstructed. A dirty air filter restricts airflow and can affect the carburetor's air-fuel mixture.
• Linkages: Periodically inspect all throttle and choke linkages for smooth operation and proper adjustment. Lubricate pivot points as needed.
• Gaskets and Seals: Check for any signs of fuel leaks around gaskets and seals. Replace any worn or damaged components promptly.
• General Cleaning: Keep the exterior of the carburetor clean from dirt and grime. Avoid using harsh chemicals that could damage finishes or components.

Figure 9: Bottom view of the carburetor, revealing the primary and secondary throttle plates. Regular inspection of these components for smooth movement is part of routine maintenance.

Troubleshooting

While the Holley 0-80508S is factory calibrated, minor adjustments may be necessary depending on your specific engine and vehicle setup. Here are some common issues and potential solutions:

• Engine Runs Rough or Stalls:
  • Check fuel supply: Ensure adequate fuel pressure and flow to the carburetor.
  • Inspect fuel filter: A clogged filter can restrict fuel.
  • Verify vacuum lines: Ensure all vacuum lines are connected and free of leaks.
  • Check idle mixture screws: Adjust in small increments (1/8 turn at a time) to achieve the highest vacuum reading or smoothest idle.
• Hard Starting (Cold):
  • Verify electric choke operation: Ensure the choke receives 12-volt power and closes fully when cold.
  • Check choke adjustment: The factory preset choke should be sufficient, but minor adjustments may be needed if the engine is consistently too rich or lean on cold start.
• Poor Acceleration or Hesitation:
  • Check accelerator pump: Ensure the accelerator pump is functioning correctly and providing a strong fuel shot when the throttle is opened.
  • Inspect vacuum secondaries: Verify that the vacuum secondaries are opening smoothly and fully under acceleration.
  • Consider jetting: While factory calibrated, extreme altitude or engine modifications may require minor jet changes. Consult a qualified mechanic or Holley's detailed tuning guides for advanced adjustments.
• Fuel Leaks:
  • Inspect all fuel line connections for tightness.
  • Check float bowl gaskets and fuel inlet fittings for proper sealing.
  • Verify float levels: Incorrect float levels can cause fuel overflow. The carburetor features center hung float bowls for stable fuel levels.

For complex issues or advanced tuning, it is highly recommended to consult a professional automotive technician or refer to the comprehensive Holley technical documentation available online.

Specifications

Warranty Information

The Holley 0-80508S 750 CFM Classic Holley Carburetor comes with a limited warranty. For specific details regarding warranty coverage, terms, and conditions, please refer to the official warranty documentation provided with your product or visit the Holley website.

Support and Resources

For further assistance, technical support, or detailed tuning guides, please utilize the following resources:

• Official User Manual (PDF): A comprehensive PDF version of the user manual is available for download. This document provides in-depth information on installation, tuning, and maintenance. You can access it via this link: Holley 0-80508S User Manual PDF.
• Holley Website: Visit the official Holley website for product information, FAQs, technical articles, and contact details for customer support.
• Authorized Service Centers: For professional installation, service, or complex troubleshooting, contact an authorized Holley service center.