A long block is an engine that includes the block, pistons, crankshaft, and cylinder head, but not the accessories bolted on the outside

When an engine fails or wears out, you have choices about what to replace. A long block is a middle ground between buying a completely bare engine block and buying a fully assembled engine ready to install. It contains the core working parts — the metal block itself, the pistons that move up and down inside it, the crankshaft that converts that motion into rotational power, and the cylinder head on top — but it does not include the fuel injectors, alternator, water pump, air intake, or other bolt-on systems.

The term "long block" exists because it is longer than a "short block" (which is just the block, pistons, and crankshaft) but shorter than a "crate engine" or "complete engine" (which arrives with everything attached and ready to run). Understanding which one you need depends on what parts you already have, how much work you want to do yourself, and how much money you want to spend.

Key Takeaways

  • A long block includes the engine block, pistons, crankshaft, and cylinder head, but not fuel injectors, alternators, water pumps, or other external parts.
  • Long blocks cost less than complete crate engines because you reuse your existing accessories, but they require more labor to install.
  • You need a long block when your original engine's internal parts have failed but your accessories like the alternator and water pump are still good.
  • Installation requires removing your old engine, transferring over all the bolt-on parts, and reconnecting fuel, cooling, and electrical systems.
  • Long blocks typically come with a warranty that covers the internal engine parts but not the work to install them.

What parts come with a long block and what you have to add

A long block arrives as a complete internal engine. It has the cylinder block (the main metal casting), all the pistons and rings, the crankshaft, the connecting rods, the camshaft, the cylinder head with valves, and gaskets sealing everything together. Some long blocks also include the intake and exhaust manifolds bolted to the head.

What you must provide or transfer from your old engine includes the alternator, starter motor, water pump, fuel injectors, fuel rails, ignition coils, air intake manifold (if not included), thermostat housing, oil pan, and any emissions equipment specific to your vehicle. You will also need to transfer your engine mounts, brackets, and any custom modifications your car requires. The exact list depends on your vehicle's year, make, and model.

Long block versus short block versus complete engine

A short block contains only the block, pistons, crankshaft, and connecting rods — nothing else. You have to add the cylinder head, all valve train components, and every accessory. Short blocks cost the least but require the most work and informed to assemble. Most people do not buy short blocks unless they are rebuilding an engine themselves or have a machine shop doing the work.

A long block includes everything a short block has, plus the cylinder head and valve train already installed and timed correctly. You still transfer your accessories, but the hardest part — getting the head and internal timing right — is already done. This is the most common choice for someone replacing a failed engine without doing a full rebuild.

A crate engine or complete engine arrives fully assembled with the alternator, water pump, fuel injectors, intake manifold, and other accessories already bolted on. You unbolt your old engine, bolt in the new one, and reconnect hoses and wiring. Crate engines cost significantly more but require the least labor and the fewest decisions about which parts to keep.

When to choose a long block over other options

Choose a long block if your original engine's internal parts have failed — a cracked block, a seized crankshaft, worn piston rings causing oil burning, or a head gasket that cannot be sealed — but your accessories are still working. If your alternator, water pump, and starter are fine, there is no reason to pay for new ones. A long block lets you keep those parts and only replace what is broken.

Long blocks also make sense if you want to upgrade your engine's power or efficiency. You can buy a long block from a newer model year or a higher-performance version of your engine, then bolt your existing accessories onto it. This is common in the car modification community.

Do not choose a long block if you do not have the tools, space, or mechanical knowledge to remove your old engine and transfer parts. The labor cost at a shop can exceed the savings you get from not buying a complete engine. If your accessories are also failing — your alternator is weak, your water pump is leaking, your starter is grinding — a crate engine may be cheaper in the long run because you replace everything at once and get a single warranty.

What a long block installation involves

Installing a long block is not a bolt-in job. You must first remove your old engine, which means draining all fluids, disconnecting the fuel system, cooling system, electrical connectors, and exhaust, unbolting engine mounts, and lifting the engine out. This alone takes several hours even for someone experienced.

Next, you transfer every accessory from your old engine to the new long block. This includes unbolting the alternator, starter, water pump, fuel injectors and rails, intake manifold, thermostat housing, oil pan, and any brackets or sensors. You then bolt each one onto the new long block in the same position. Some parts may need new gaskets or seals because they were disturbed during removal.

Finally, you lower the new engine into the bay, bolt it to the mounts, and reconnect every hose, wire, and fuel line. You refill coolant and oil, check that everything is tight, and start the engine to look for leaks or electrical problems. A shop typically charges 15 to 25 hours of labor for this work, depending on your vehicle's engine bay layout and how many accessories need moving.

Long block warranties and what they cover

Long blocks come with warranties that cover the internal engine parts — the block, pistons, crankshaft, cylinder head, and valves — against defects in materials or workmanship. Warranty length varies by seller and can range from 30 days to three years or more. Some sellers offer unlimited-mileage warranties; others limit coverage to a certain number of miles or months.

Warranties do not cover the labor cost to install the long block, the cost to transfer your accessories, or problems that arise from installation mistakes. If a bolt is overtightened and cracks the block, or if the engine is not timed correctly during assembly, the warranty does not explore. Warranties also do not cover wear and tear after installation — if the engine runs fine for two years and then a piston ring wears out, that is normal wear, not a defect.

Before buying, ask the seller what the warranty covers, how long it lasts, whether it transfers if you sell the vehicle, and what proof of purchase or installation they require. Some sellers require that a certified shop perform the installation; others do not.

Where to buy a long block and what to expect

Long blocks are sold by engine rebuilders, salvage yards, online engine retailers, and some new-car dealerships. Rebuilt long blocks (taken from a used engine, cleaned, and inspected) cost less than remanufactured ones (completely disassembled, worn parts replaced, and reassembled to factory specs). Remanufactured long blocks typically come with longer warranties and more thorough testing.

When shopping, confirm that the long block matches your vehicle's year, make, model, and engine size. An engine from a different year or model may not bolt into your mounts or connect to your wiring harness. Ask whether the long block includes the intake and exhaust manifolds, because some sellers remove these to reduce shipping weight. Get the warranty terms in writing and ask whether the seller will help troubleshoot problems after installation.

Shipping a long block is expensive because of its weight — typically $300 to $800 depending on distance. Some sellers include shipping; others charge it separately. Budget for this cost when comparing prices.

Frequently Asked Questions

Can I install a long block myself if I have never done engine work before?

Removing and installing an engine requires special tools like an engine hoist, jack stands, and torque wrenches, plus knowledge of your vehicle's specific layout. If you have never done this work, a shop is safer and faster. Mistakes during installation can damage the new engine or create dangerous leaks. If you want to learn, find an experienced mechanic willing to supervise.

How long does it take a shop to install a long block?

Most shops need two to four days of work spread over one to two weeks, depending on how busy they are and how many problems they find during removal. Some vehicles are harder to work on than others. Ask your shop for an estimate before you commit.

Is a used long block from a salvage yard as reliable as a rebuilt one?

A used long block from a salvage yard is cheaper but comes with unknown history and usually no warranty or a very short one. A rebuilt or remanufactured long block costs more but has been inspected, worn parts replaced, and tested. For most people, the extra cost of a rebuilt long block is worth the peace of mind.

What if the long block does not fit my engine bay?

This is rare if you buy the correct year and model, but it can happen if the long block is from a different generation or if your vehicle has custom modifications. Confirm the engine code and dimensions with the seller before purchase. If there is a mismatch, you may be able to return it, but shipping costs will be your responsibility.

Do I need to change the oil and filter right after installation?

Yes. New long blocks contain assembly oils and metal particles from machining. Run the engine for a few minutes, then drain and replace the oil and filter. Some shops do this as part of the installation; others charge extra. Confirm what is included before work begins.