Here's a breakdown of what's involved:
1. Engine Compatibility and Parts Assessment:
* Engine Mounts: The 4.3L's engine mounts are different from the 2.8L's. You'll need the correct mounts for the 4.3L in an S-10, likely requiring custom fabrication or sourcing specific mounts. The Astro van parts might not be directly compatible.
* Transmission: Your 5-speed transmission *might* bolt up to the 4.3L, but this is NOT guaranteed. The bellhousing pattern needs to match. If they don't match, you'll need a different transmission. Check the bellhousing bolt patterns carefully. The Astro van transmission might not be the right one.
* Wiring Harness: The 4.3L's wiring harness is completely different. You'll need a harness from a donor S-10 with a 4.3L, or you'll face a major rewiring project. Using a harness from the Astro van is unlikely to work.
* Computer (ECU): The 4.3L needs its own computer to run correctly. Again, this needs to be from an S-10 with a 4.3L, or carefully programmed (potentially requiring a custom tune). The Astro van's computer won't work.
* Exhaust System: The exhaust manifolds and system will not be compatible. You'll need a 4.3L S-10 exhaust system.
* Drive Shafts: The drive shafts might need to be shortened or lengthened depending on the exact 4.3L configuration and the S-10 model.
* Cooling System: The radiator, hoses, water pump, and thermostat might need to be upgraded to handle the larger engine.
* Fuel System: The fuel pump and fuel lines might need to be upgraded or replaced to support the larger engine's fuel needs.
* Other Components: Consider the alternator, power steering pump, and other accessories; they might need to be swapped or adapted.
2. The Process (Highly Simplified):
1. Removal of 2.8L: Carefully remove the old engine and transmission.
2. Engine Bay Preparation: Clean the engine bay thoroughly. You may need to modify or replace components to accommodate the 4.3L.
3. Installation of 4.3L: Install the 4.3L engine and transmission (if compatible, otherwise obtain a suitable one). This will involve mounting the engine, connecting the transmission, and aligning the driveshafts.
4. Wiring and Computer: This is the most complex part, requiring careful routing of the correct wiring harness and proper installation of the compatible computer.
5. Exhaust and Fuel System: Install the appropriate exhaust and fuel system components.
6. Cooling System: Connect the cooling system components.
7. Testing: After everything is connected, you'll need to test the system thoroughly. This includes checking for leaks, proper functioning of all systems, and obtaining a proper tune if necessary for your specific configuration.
3. Crucial Considerations:
* Skill Level: This is a major project requiring significant mechanical skills. If you are not comfortable with engine swaps, you should seek professional help.
* Tools and Equipment: You will need a wide range of tools and equipment, including engine hoist, engine stand, torque wrenches, and diagnostic equipment.
* Parts Sourcing: Sourcing the correct parts, especially the wiring harness and computer, is crucial for success.
* Safety: Always prioritize safety when working on your vehicle.
In short: While it's *possible* to swap a 2.8L for a 4.3L, it's a very involved project requiring extensive mechanical knowledge, the correct parts (most likely not those from your Astro van), and careful planning. Unless you have extensive experience with engine swaps, it's strongly recommended to seek professional assistance. The potential for problems and unexpected costs is high.
