When choosing materials for a carburetor pre-heater hose, the following options are considered the best due to their specific properties that handle heat and fuel exposure:

1. Silicone: Silicone hoses are known for their excellent heat resistance, flexibility, and durability. They can withstand high temperatures, making them ideal for pre-heater applications.

2. Rubber (EPDM): Ethylene Propylene Diene Monomer (EPDM) rubber is another good option. It has good heat and chemical resistance, which makes it suitable for automotive applications where exposure to heat and fuels is common.

3. Aluminum: Aluminum hoses are lightweight and have excellent heat resistance. They can effectively dissipate heat and are often used in performance applications.

4. Stainless Steel: Stainless steel hoses are highly durable and resistant to corrosion and high temperatures. They are ideal for high-performance applications where durability and heat resistance are critical.

5. Nylon: Reinforced nylon hoses offer good heat resistance and strength. They are often used in automotive applications due to their durability and flexibility.

6. Flexible Metal Conduits: These conduits, often made from materials like stainless steel or aluminum, provide excellent heat resistance and are flexible enough to accommodate different routing needs in the engine bay.

When selecting a material, consider factors such as the operating temperature range, the environment in which the hose will be used, and compatibility with fuels and other chemicals.