A common misconception is that the terms “short block” and “long block” refer to the actual length of an engine, but that is not accurate. If you’re purchasing a used engine or even a crate engine, you’ll need to decide which to buy. In this case, it isn’t best to judge by price, because the option you choose depends on what usable parts you have on hand.
When it comes to purchasing used or crate engines, short blocks fall at the bottom of the price list. This is because a short-block engine is only about one-third of a complete engine. Short blocks include the block itself, freeze plugs, oil filter boss, pistons, connecting rods, bearings, crank pulley boss, front engine cover and a timing component set -- on pushrod-type engines. If you purchase a short-block engine, you furnish the intake and exhaust manifolds, cylinder heads, pulley system, accessories, lifters and pushrods. The engine's oil pump may or may not be included, depending on where you purchase the engine. Sometimes builders include the water pump on engines that uses a water pump that is timing belt driven. You’ll also need the oil pan from your original engine when you assemble a short block engine.
Short block engines are the best way to go if you have damaged only your engine block. You can use all of the parts from your original engine to complete the short-block engine. If you need to replace your cylinder heads too, it is often cheaper to start out with the long block.
Long block engines are priced higher than short blocks, but they are almost complete engines. They consist of everything included in the short block but include cylinder heads as well. The only parts you need from the original engine are the intake and exhaust manifolds, harmonic balancer, oil pan and accessories. All of the engine internals, with exception of the oil pump in some cases, are included with a long block. The oil pump may or may not be included depending on where you purchased the engine. You’ll most likely need to transfer the timing cover and oil pan from the original engine to the new long block assembly.
There is no set standard for what must be included in short or long block engines. Parts included with the engine you receive may vary from supplier to supplier. When purchasing a used or crate engine, ask for a detailed build sheet describing exactly what parts are included and what parts you must supply. It will save you money in the long run.
