Engine Long Block
The engine has two sub-assemblies: the long block and short block. The block and rotating assembly such as the crankshaft, pistons, and rods comprise the short block, which is also called the engine core. Aside from the cylinder block, this also comes with the front cover, pulley hub, and engine plates. This is more like a stripped engine. The long block, on the other hand, comes with cylinder heads that are bolted on. This, however, doesn't come with the fuel system or accessory drive and manifolds for the intake or exhaust.
Parts of the long block engine
Engine block. The block is typically manufactured out of cast iron alloy. It may also be made from cast aluminum or different aluminum alloys. This solid metal that serves as a main foundation for the engine is cast into a shape and machined to add further details.
Cylinder heads. Cylinder heads can be constructed out of iron or aluminum. These heads help trap combustion gases within the cylinder. Overhead-cam engines may be built with one or two camshafts.
Rotating assembly. The job of the rotating assembly is to transform the piston's vertical movement (up-down motion) into rotational movement. The pistons are linked through rods that are attached to the crankshaft, which is then connected to the transmission via a flywheel or clutch. With combustion gases pushing down on the pistons, the drivetrain is powered through the crankshaft.
The camshaft may not be considered by some engine builders as part of a long block sub-assembly. In some cases, this is considered a separate unit or piece, but in some stock rebuilt long blocks sold by auto retailers, the sub-assembly may include the camshafts.
Why it may be better to buy an engine long block than a short block
A good number of engines that can be ordered from auto retailers are actually pre-assembled long blocks. Those who sell used cars with new engines may have replaced just the long block and have retained everything else. With cylinder heads already pre-installed, rebuilt, and refreshed, putting in a new sub-assembly is quite easy, almost hassle-free. You can also expect a more or less great performance from a long block. For some car enthusiasts, vehicle owners, and auto restorers, it just makes more sense to purchase a long block engine.
Tips when buying a long block
When in the market for a new one, it pays to know a few things that you should be looking for in an engine long block.
- Look for a long block that's specially designed or built for the vehicle that you're driving. Be vehicle-specific in your search. Get a list of options that match the make, model, and year of your vehicle to make sure that the sub-assembly you'll buy will fit and work as expected.
- Choose from well-known brands or manufacturers. Some manufacturers can actually ensure that remanufactured engines can stand the test of time, sometimes better than rebuilt types. Their engines are assembled by a pool of skilled technicians in a controlled setting, and the assembled engines are tested using all the right equipment to make sure that they'll have uncompromising quality and perfect fit with all the right details in place.
- Invest in quality engine sub-assemblies. Search for a long block that's made from high-grade materials. Check the included components and features.
- Get yourself a great manufacturer warranty for the long block. This will ensure top product quality. In case the long block fails or wears out prematurely, you have a warranty that you can always turn to for service, repair, or replacement. Some manufacturers can offer as much as a 3-year or 100,000-mile warranty.
If you're not a mechanic or a well-experienced DIYer, it's better to leave the installation of the engine long block to a pro.