How to Build a Small Block Chevrolet Racing Engine
With the availability of carefully selected aftermarket parts and attention to detail, the small-block Chevrolet engine (SBC) is capable of well over 700 horsepower in standard 23-degree valve-angle configurations. Attaining those power levels is largely a matter of careful planning, preparation and assembly, and with the same careful thought, lower-output racing engines can also produce respectable performance and winning results as well. In any event, a well-planned engine build can provide a reliable competition engine.
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Things You'll Need
- Parts research, assembly guide and instructions with clearance and torque values for fasteners
- Camera, notepad, pencil/pen/felt tip marker, adhesive notes, sealable freezer bags
- Clean 10' x 10' workspace with bench and organizing bins or trays
- Engine hoist and stand
- Engine dolly or hand cart
- Various mechanics tools, including cleaning brushes, crankshaft socket, torque wrench, files, piston ring expander and compressor, measuring devices (inside/outside micrometers, gauges and calipers)
- Air compressor
- Assembly lube
- Gaskets/seal set, sealants
- High-temperature engine paint
- Engine components/sub-assemblies
Instructions
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Research Engine Combinations
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Search for examples of engine combinations that are similar to the desired output of the engine being designed. Many online resources--such as forums and blogs--provide detailed examples of builds that have been undertaken, and there are many good books available with which to gain an understanding of the parts selection process (see Resources below).
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Pay attention to--and make note of--special parts and procedures that can add additional power that is often overlooked. Be aware that almost all the power production is a result of the induction, heads and valve timing. Design the short-block assembly to be capable of withstanding that level of output.
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Locate and interview a machinist that you are comfortable with in performing the necessary machine work and blueprinting to your engine components. Find one who is familiar with your type of engine program and racing, and who can offer suggestions for more difficult parts selection such as induction and camshaft as well as lower engine components.
Disassembly
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Remove the engine and attach the engine stand brackets to the rear of the engine. Transfer the engine from the hoist to the engine stand. Take pictures from several angles while disassembling. Begin the disassembly by removing accessories--if attached--and set them aside in an organized manner.
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Remove fasteners to the carburetor (or throttle body, if injected) and distributor and place these in an organizing bin/tray with a labeled adhesive note. Continue in a top-down, front-to-back order with the intake manifold, valve covers, head bolts and heads, pushrods and lifters, water pump and other external components and carefully set all these aside.
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Rotate the engine 180 degrees on the stand and remove the starter, oil pan bolts, oil pan and oil pump (and windage tray, if equipped). Remove the final external components such as the flywheel/flexplate and harmonic balancer. Use a balancer puller to remove the balancer, and remove the timing cover bolts and cover. The engine is now at the “short-block” stage, and disassembly can be completed. Remove the three bolts holding the camshaft timing gear/chain and set the chain aside. Snugly reattach the cam gear and carefully slide the camshaft forward out of the block. Remove the rod bolt fasteners and carefully slide the rod/piston assemblies out of each bore, placing them aside in an organized manner.
Machining, Preparation and Assembly
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Provide your machinist with the components needed to machine key finish-tolerances such as piston-to-cylinder wall clearance, rod and main bearing sizes, and piston pin bore clearances, among others, as well as to make performance modifications. Follow along with the progress on your engine preparation. When machining is completed, the components will have precise component assembly relationships. Take delivery of your parts when machining is done and thoroughly clean every remote portion and galley of the block. Dry everything off with compressed air immediately and spray the internal surfaces lightly with a rust inhibitor. Apply paint to the exterior surfaces. The engine is now ready for test assembly.
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Organize all reconditioned or replacement parts so that they are available for reassembly. Reassemble the components in reverse order of dissassembly using new bearings, rings and seals. Reinstall the components slowly and methodically with ample amounts of assembly lube in friction areas/bearing surfaces according to recommended procedures from the assembly guide, taking careful note of any unusual interferences. Use the piston ring compressor to allow the piston/rod assembly to slide into the bore, and then fasten the rod caps. Turn the rotating assembly carefully. If interference is found anywhere, disassemble and correct. Torque and measure all clearances with particular attention paid to rod and main bearings and thrust clearances.
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Verify camshaft timing with a degree wheel according to the cam maker’s instructions with cylinder heads and camshaft installed to ensure proper valve events, and make certain there is proper piston-to-valve clearances. Tighten all fasteners to proper torque specifications ONLY if rotation is free and there are no improper interferences. Install all sheet metal and top-end parts, such as intake manifold, distributor and carburetor.
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Prime the oil system once all necessary parts are installed, and prepare the engine for test running, dynamometer testing or reinstallation in the car.
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