The Edelbrock 1405 carburetor is a high-performance component designed for a range of engine applications. It is part of the Edelbrock Performer Series, which is known for its factory calibration and ease of adjustment. This article provides a detailed and comprehensive guide to installing and calibrating the Edelbrock 1405 carburetor, based exclusively on information from official documentation and installation instructions provided by Edelbrock.
Installation Overview
The Edelbrock 1405 is part of a broader series of carburetors that are factory-calibrated, flow-tested, and preset for optimal performance. Before beginning the installation process, it is essential to review and follow the installation instructions that accompany the carburetor. These instructions are critical to ensuring that the component is installed correctly and functions as intended.
Improper installation may result in poor engine performance or damage to the vehicle. Therefore, it is recommended to either follow the installation steps carefully or seek the assistance of a qualified mechanic if there is any uncertainty.
Preparation and Required Tools
Prior to installation, it is important to ensure that the correct size carburetor (in cubic feet per minute or CFM) is selected for the specific engine application. The idle mixture screws should also be properly adjusted as outlined in the owner's manual. The carburetor should be installed according to the manufacturer’s specifications to ensure proper function and longevity.
A torque wrench should not be used on NPT fittings. Instead, Teflon tape or paste should be applied to the first few threads of the NPT fittings before installation. These fittings should be tightened by hand and then slightly tightened using a box-end wrench. Over-tightening can damage the intake manifold due to the tapered threads on NPT fittings.
Some Edelbrock intake manifolds may require the use of a #2732 spacer. Additionally, if the original engine uses a bypass to the intake manifold, it should be transferred to the Edelbrock intake to avoid potential overheating issues.
Step-by-Step Installation Process
Positioning the Carburetor: Begin by placing the carburetor on the intake manifold. Ensure that all mounting surfaces are clean and free of debris. If an airhorn gasket is being reused, inspect it for any tears or damage. If it remains intact, it can be reused; otherwise, a new gasket should be installed.
Mounting the Carburetor: Secure the carburetor to the intake manifold using the appropriate mounting bolts. Tighten the bolts evenly to avoid warping the manifold or damaging the gasket.
Connecting the Fuel Lines: Attach the fuel lines to the carburetor’s fuel inlet and outlet ports. Apply Teflon tape or paste to the threads of the NPT fittings before installation. These fittings should be tightened by hand and then lightly snugged using a box-end wrench. Avoid over-tightening to prevent damage to the intake manifold.
Electrical Connections: If the carburetor is equipped with an electric choke, connect the power wire. The choke has a low amp draw (0.5 amps), so a fuse is not strictly necessary. However, a 10-amp fuse can be used if desired for added safety.
Air Cleaner and Hood Clearance: If the engine is fitted with an air cleaner, ensure that there is sufficient hood clearance to prevent contact or obstruction. A simple test involves placing a few pieces of clay or foil balls on the air cleaner and gently closing the hood. If resistance is felt, stop and adjust the air cleaner or hood as necessary.
Final Inspection: Once all components are installed, visually inspect the carburetor and its connections for any signs of leaks or misalignment. Ensure that all fittings are secure and that the carburetor is properly seated on the intake manifold.
Calibration and Adjustment
The Edelbrock 1405 carburetor is designed to allow for quick and easy adjustments without the need to remove the carburetor from the intake manifold. This feature makes it convenient for users to fine-tune the carburetor based on their specific engine requirements.
Calibration Reference Charts
Each model of the Edelbrock Performer Series carburetor includes a Calibration Reference Chart, which consists of two sections: a Calibration Table and a Rod/Jet Reference Chart. These charts are essential tools for determining the appropriate rod and jet combination for a given application.
To use the Calibration Reference Chart, follow these steps:
Determine the Calibration Reference Number: After reviewing the calibration procedures in the owner's manual, decide whether the carburetor should be adjusted to run richer or leaner in the Cruise Mode and Power Mode. Select the number closest to the intersection of your Cruise and Power Mode selections. This is your calibration reference number.
Refer to the Rod/Jet Reference Chart: Locate your calibration reference number on the Rod/Jet Reference Chart. This will indicate the rod and jet combination that should be used for your specific application.
For example, if the carburetor model is 1405 and the calibration reference number is determined, the Rod/Jet Reference Chart will provide the corresponding rod and jet sizes.
Lean and Rich Adjustments
Adjusting the carburetor to run lean or rich can impact engine performance and fuel efficiency. However, it is important to note that there is no guarantee that leaning the carburetor will improve gas mileage, as the effects vary depending on the engine's design and operating conditions.
To lean the carburetor, refer to the calibration chart and make the necessary adjustments in different modes, such as Cruise and Power. Start with small adjustments and monitor the engine’s performance and spark plug condition to ensure that the carburetor is not over-leaned.
Maintenance and Troubleshooting
Regular maintenance is essential to ensure the longevity and performance of the Edelbrock 1405 carburetor. One common issue that users may encounter is a fuel odor or flooding condition, which can be caused by several factors.
Fuel Odor and Flooding
The Edelbrock Performer/Thunder series carburetors feature vented float bowls, which can lead to fuel fumes being noticeable under the hood, especially when the air cleaner is removed. Heat soak, which occurs when the engine is turned off and the fuel in the float bowls heats up, can cause the fuel to expand or even boil, leading to fuel vapor being forced through the primaries and float bowl vents.
To mitigate this issue, Edelbrock recommends the use of a heat insulating spacer to keep the carburetor cooler. Additionally, if the carburetor is experiencing a flooding condition, the following steps should be taken:
Check Fuel Pump Pressure: The fuel pump pressure should not exceed 6.5 psi. If it does, the pressure should be adjusted accordingly.
Inspect Needle and Seat Assembly: Remove the top of the carburetor and check for debris in the needle and seat. Ensure that the needle tip is not damaged or compromised.
Inspect Float Condition: While the float is off, shake it to check for any signs of fuel inside. If fuel is present, the float should be replaced.
Clean Idle Circuit: To clean the idle circuit, remove the carburetor from the intake manifold and the top of the carburetor. Remove the primary venturi boosters and clean all passages, especially the small idle jet. The idle mixture screws should also be removed and the passages cleaned to ensure free flow.
Additional Considerations
Fuel Filter Requirements
The Edelbrock 1405 carburetor does not include an internal fuel filter. Instead, a screen is installed into the needle and seat assembly to trap large pieces of debris. However, this is not a substitute for an external fuel filter, which is required for proper operation. An external fuel filter should be installed upstream of the carburetor to prevent debris from entering the fuel system.
Electric Choke Considerations
The electric choke on the Edelbrock Performer/Thunder series carburetors does not require a fuse due to its low amp draw (0.5 amps). However, if a user prefers to install a fuse for added safety, a 10-amp fuse can be used on the choke power wire.
Spark Plug Wire Installation
For those installing universal spark plug wires, it is important to determine the required length for each wire and choose the shortest wire from the kit that is long enough to reach from the distributor to the spark plug. If necessary, the wire can be cut to the proper length using a side cutter or razor blade.
The wire should be lubricated with the included silicone before sliding the appropriate boot over the end. The insulation should be stripped at least 1/2 inch from the conductor, and any loose strands should be trimmed away. The conductor should then be folded back over the insulation, and the appropriate terminal should be crimped onto the wire using a terminal crimping tool.
Conclusion
The Edelbrock 1405 carburetor is a versatile and high-performance component designed for a wide range of engine applications. When installed and calibrated correctly, it can significantly enhance engine performance and responsiveness. However, it is essential to follow the manufacturer’s instructions carefully to avoid potential issues such as poor performance, fuel odor, or flooding.
By following the step-by-step installation process and using the Calibration Reference Charts, users can fine-tune the carburetor to meet their specific needs. Regular maintenance and troubleshooting can also help ensure that the carburetor continues to operate efficiently over time.