A long block engine is a complete engine package to be installed in a vehicle. A long block differs from a short block in that the short block refers only to the part of the engine below the head gasket. The long block excludes some parts from the complete engine assembly, including the flywheel, timing cover, oil pan, valve covers, exhaust manifolds and the intake. Purchasing a long block engine allows you to completely change out the engine in your vehicle; however, there are a few things to consider before buying one.
ECU and Transmission Compatibility
Although a long block engine is usually defined as a complete motor assembly, you need to make sure that you have a compatible transmission and electronic control unit for the engine. Also, you may need various other parts such as mounts, wiring harnesses, axles, shift linkages, sensors and other things to make an engine swap work.
Long Block Expense vs. Short Block Expense
Because a long block engine also includes the head gasket and cylinder head assembly, it is much more expensive than a short block engine which only contains the parts of the engine below the head gasket. If you are replacing an engine in a vehicle with the exact same type of engine, you might want to see if you can reuse the head gaskets or cylinder heads in order to avoid the cost of the expense of a long block engine.
Short Block Sub-Assembly
A short block sub-assembly in an engine generally consists of every part of the engine that sits above the oil pan, but below the head gasket. This includes the water jacket, several pistons, the valve train, the crankshaft and several other parts as well. Depending upon the layout of the cams in the engine, there may be other components situated within this region and as part of the short block too. In-block cam setups involve the camshaft and the timing gear for the cams as well. This is in opposition to the overhead cam style of engine design, in which the cams are located outside of the engine short block entirely.
Long Block Sub-Assembly
The long block always contains within its list of engine components all of the components of the short block. This means that the short block is always part of the long block, but not vice versa. In addition to the various parts of the short block, the long block typically extends up to the head gasket and gasket assembly as well. Therefore, a long block sub-assembly also includes the cylinder head, the valve locks, valve keepers, valve springs, valve guides and the valves of the engine themselves. In flathead engine designs, the long block sub-assembly also includes the valve train if that wasn't already a part of the short block setup either.
Cheap Long Blocks
When purchasing a long block engine, you really get what you pay for. You should always purchase your long block from a reputable remanufacturer or even the car manufacturer. When purchasing a long block engine at a very cheap price, many components inside the engine may not actually be new and may have little or no useful engine life left in them.
Where to Buy a Long Block Engine
You can buy a long block engine from a local auto parts dealer, from an engine rebuilder or performance engine manufacturer, online or from an auto salvage dealer. You should expect to pay $5,000 or more. This depends on the type of long block engine you need and the additional components to rebuild the block. You may also need to factor in the labor costs of a mechanic or repair shop if you don't have the appropriate tools or equipment (like an engine lift) to install the block.
Getting a Long Block Price List
Calling around to different dealers that sell engine parts will give you an idea of what long blocks are available and for what price. Find out whether the long block is reliable and has passed a compression test. A compression test will determine if the long block is in good condition, that it does not leak and that it won't fail once installed. This test may cost you an additional $500 if performed by the dealer that sells you the engine.
There are many reasons to make a distinction between the short block and the long block in the engine of a car. There are hundreds of different subcomponents within each car engine. It's easier for auto experts and mechanics to split up the components into like categories and groups. Because the short block and long block can be removed or installed as a single unit, they naturally fit as one of these sub groups. Breaking the engine components up into categories also helps to identify where any problems that develop in your engine are pinpointed.