Re-assembling a Chevrolet 350-cubic-inch motor is a detailed, step-by-step, process involving many expensive parts and requires careful attention to detail. There are a few steps -- often neglected by engine builders -- that should be performed prior to final assembly. Once you have determined that all parts will fit properly, you can begin the assembly process.
Disassemble the engine in it's entirety. A proper engine build up requires a bare block as a starting point. After all parts have been removed from the engine block, thoroughly clean the block and any parts that will be re-used. Make sure to remove any freeze plugs and clean out all internal oil and coolant passages with a high pressure hose to ensure removal of all debris. Any piece of debris left in the engine will eventually find it's way into a bearing or similar engine part and could cause a serious malfunction.
Test fit all engine parts. This is a critical step in engine building often overlooked by laymen and professionals alike. Test fitting of engine parts includes, but is not limited to; partial installation of the crankshaft (to ensure the counterweights clear all obstructions when spun), test fitting all pistons in engine cylinders, installation of cylinder heads and all valve train components (to insure piston and valve clearances), and camshaft installation (to check lifter clearances and valve timing). Be sure to install bearings and lubrication as needed, so as not to damage any journal surfaces.
Machine parts as necessary. This usually includes removing casting flash, checking the radius of, or enlarging, oil passages, and smoothing drain-back areas in the lifter valley. Every engine is unique and will require different modifications. If you are unsure about something, check with a professional before attempting any modifications.
Install all engine parts. Start with by installing all the bearings and properly lubricating all parts. Install the crankshaft first, followed by the connecting rods, pistons and piston rings. After these parts (called the rotating assembly) have been installed and properly torqued to manufacturer specifications, install the intake manifold, camshaft, cylinder heads, and valve train. Proper installation of the valve train could easily encompass an entire new article, so refer to manufacturer specifications for this process. Install the oil pan and cylinder head covers. After the valve train has been installed and properly clearanced, install the carburetor and part of the throttle linkage. Install the engine's peripheral systems. These include the alternator, air conditioning compressor (if equipped) and power steering pump.
Fasten the engine to the vehicle. At this stage the engine is ready to be lowered into the engine bay and attached to the mounting points. After bolting the engine to the vehicle chassis, mount the exhaust manifolds, engine starter and ignition system. Attach the serpentine belt (or belts) and spark plugs, and add engine fluids. Install the throttle linkage, coolant hoses, and all other necessary hoses and wires.
Start and test run the engine. Break in the engine according to manufacturer specifications.
