Home >> Tech Help >> Short vs. long blocks

Short vs. Long Block – A Brief Explanation Whether you are considering replacing the existing engine in your car with a performance engine suitable for racing, or you merely wish to repair, rebuild, or tweak the engine you already have, understanding the basics of engine assemblies is integral to your ability to make informed decisions about the appropriate engine or engine modifications for your vehicle. One key element of this basic engine knowledge, an element that will help you make your final purchase selection, is the understanding of the difference between short and long block engines. Also, always remember that any engine modifications made will likely affect your insurance rates.   The terms "short block" and "long block" are both used to describe engine sub-assemblies – portions of an entire engine. Here's a breakdown of what each means: Short Block This is the portion of the engine block above the oil pan but below the head gasket. In flathead engines (typically used in performance modified Fords), the short block will also include the cam and valvetrain, while those parts would not be included in an overhead valve engine.   Short blocks are usually purchased in order to upgrade the piston size or bore, or the water jacket, and such assemblies typically include the crankshaft installed and balanced along with the main bearing. Long Block The term "long block" also refers to an engines sub-assembly, but in this case the sub-assembly is also a superset that includes the short block. (In plain English, the short block is a part of the long block.) Elements of the long block engine typically include the following parts: Short block. Cylinder head. This may be either new or remanufactured, and includes a new head gasket torqued to the correct specification. Complete cylinder heads also include either new or reconditioned valves, valve springs, valve guides and seats (if applicable), valve locks and valve keepers. . The bare head will be free of cracks, holes, or warping. On flathead engines, the valvetrain is also included in the long block, if it wasn't part of the short block already. On most engines, the camshaft will be installed, and on those engines with timing gears, it will usually be times as well.   In addition, when performing a long block engine replacement, several parts from the original engine will need to be swapped out, and installed on the long block. These parts include the intake manifold, alternator, power steering pump (if there is one), and if the car is air conditioned, the air conditioner compressor.   Why Choose Short or Long? Factors affecting your choice of engine blocks include cost and the amount of work. A short block assembly includes less parts, and costs less to purchase, and you'll save money since you can reuse some old engine parts, but it will require more labor. A long block engine, on the other hand, is as close to a complete engine assembly as it's possible to buy. Because more parts are included, it will cost more to buy.

-- Have you written a great automotive tech article and want to share it? Submit it here. (Flatlander Racing does not take responsibility for Tech Article accuracy)

Sales/Tech Line: (603) 378-0090 Email: tech@flatlanderracing.com Thank You for visiting Flatlander Racing *All prices on this site are subject to change without notice. Flatlander Racing™ disclaims responsibility for any printing or typographical errors, and does not guarantee that all information is accurate. Home  Policies  SiteMap  Translate  Import Parts  Can't Find Part?  Contact  Order Online