I. Preparation:
1. Gather Tools and Parts: You'll need a complete set of metric and SAE sockets, wrenches, ratchets, extensions, a torque wrench, a camshaft installation tool (to properly install the cam), valve spring compressor, timing chain/belt tools (depending on your setup), a new timing chain (or belt) and gears (if necessary), gaskets (cam bearings, timing cover, etc.), new lifters, pushrods (check their length), and possibly new rocker arms. A good quality repair manual is essential. Consider a shop press for ease of lifter installation.
2. Drain Fluids: Drain the engine oil, and coolant.
3. Remove Accessories: Remove the air cleaner assembly, distributor, fuel lines (if applicable), alternator, power steering pump, and any other components obstructing access to the timing cover.
4. Remove Timing Cover: Remove the timing chain cover, carefully noting the position of all components. You may need to remove the water pump as well.
II. Camshaft Removal:
1. Remove Timing Chain/Belt: Remove the timing chain or belt, making sure to carefully note the position of the crankshaft and camshaft sprockets. Use a timing chain/belt alignment tool to prevent misalignment during reassembly.
2. Remove Cam Bearings: Carefully remove the camshaft bearings. These are usually pressed in, and may require a special tool or a well-controlled press.
3. Remove Camshaft: Once the bearings are out, the camshaft should slide out.
III. Camshaft Installation:
1. Install New Cam Bearings: Install the new cam bearings (if needed), ensuring they are seated correctly. Use a press if necessary.
2. Install Camshaft: Carefully install the new camshaft, ensuring it's properly aligned. Use the camshaft installation tool to properly seat the camshaft in the bearings.
3. Install Lifters: Install the new lifters, ensuring they are seated properly. A shop press makes this considerably easier.
4. Install Pushrods: Install the pushrods, ensuring correct length and positioning. There may be slight variations in length depending on the camshaft. Double check this carefully.
5. Install Rocker Arms: Install the rocker arms.
6. Install Timing Chain/Belt: Carefully install the timing chain or belt, using the alignment tool to ensure proper timing.
7. Install Timing Cover: Install the timing cover and all related gaskets.
IV. Reassembly:
1. Reinstall Accessories: Reinstall all the components you removed earlier, paying close attention to proper torque specifications.
2. Refill Fluids: Refill the engine oil and coolant.
3. Start the Engine: Carefully start the engine and check for leaks and proper operation.
V. Important Considerations:
* Timing: Precise timing is critical. Use the proper alignment tool and carefully follow the instructions in your repair manual. Incorrect timing can cause serious engine damage.
* Torque Specifications: Use a torque wrench and follow the manufacturer's specifications for all bolts and nuts.
* Lifter Installation: Take your time and ensure lifters are correctly seated to avoid engine damage.
* Professional Help: If you're not comfortable performing this task, it's best to take your vehicle to a qualified mechanic. This job requires expertise and precision.
This is a general overview. A detailed service manual specific to your 1990 Chevrolet 350 V8 pickup is absolutely crucial. Improperly performing this task can result in serious engine damage. Consult a professional if you lack experience.
