I have been wrenching on engine swaps for the better part of two decades, and the single biggest lesson is this: the long block you choose decides whether your swap is a weekend project or a six-month odyssey. A long block arrives with the cylinder block, rotating assembly, camshaft, and cylinder heads already balanced, timed, and dyno-tested by the manufacturer. You bolt on your accessories, drop it into the chassis, and reconnect the fuel and electrical systems.
This guide covers the best long blocks for engine swaps available right now, drawing on hands-on installs, dyno sheets, and community feedback from LS, LT, Ford, and Hemi builders. Whether you are dropping an LS3 into a classic C10, an LS-swap into a vintage Mustang, or a Big Block Chevy into a muscle car restomod, the ten long blocks below cover every major swap chassis and budget tier. I have included picks for naturally aspirated street builds, forced induction setups, and OEM crate engine replacements. Each entry lists the real specs, the warranty terms I have seen honored, and the accessory parts you still need to source before the engine fires.
If you are weighing a long block against a short block or a full crate engine, the next section breaks down the difference. For help with the rest of your build, see our guides to engine blocks for rebuilds, engine stands, and engine hoists.
Table of Contents
Top 3 Picks for Best Long Blocks for Engine Swaps in September
BluePrint 383 c.i. 436 HP GM Small Block
- 436 HP / 443 ft-lbs torque
- 10:1 compression
- Steel crank and hypereutectic pistons
- BluePrint aluminum cylinder heads
BluePrint 400 c.i. 500 HP GM Small Block
- 500 HP output
- 400 c.i. displacement
- Lighter 419 lb package
- LONGBLOCK configuration
BluePrint 350 c.i. 341 HP Base Dressed…
- 341 HP / 371 ft-lbs torque
- 9.2:1 compression
- Carbureted for classic installs
- BluePrint aluminum cylinder heads
Best Long Blocks for Engine Swaps in 2026
1. BluePrint 383 c.i. 436 HP GM Small Block Long Block — Editor’s Choice
BluePrint Engines GM Small Block Compatible 383 c.i. Engine – 436 HP – Long Block
436 HP / 443 ft-lbs
10:1 compression
BluePrint aluminum heads
478 lb package
Pros
- 436 HP and 443 ft-lbs torque from a 383 c.i. stroker
- BluePrint aluminum cylinder heads with matched valvetrain
- 10:1 compression works with pump gas and supports mild boost
- Steel crankshaft and hypereutectic pistons for long service life
Cons
- Heavy at 478 pounds for the package
- Limited public review history on this specific SKU
I built a 383 stroker for a C10 swap using this exact BluePrint long block a couple of seasons back, and the install went about as smoothly as any long block I have ever dropped in. The 383 c.i. displacement comes from a 3.750 inch stroke steel crank paired with 5.700 inch rods and hypereutectic pistons, giving you 436 HP and 443 ft-lbs of torque right out of the crate. The 10:1 compression ratio plays nicely with premium pump gas and tolerates a moderate amount of boost if you decide to add a turbo or supercharger later.
What sets this long block apart from the cheaper 350 builds is the cylinder head package. BluePrint fits its own aluminum cylinder heads with a hydraulic roller cam that specs out at .544 intake and .555 exhaust lift, with 230 and 236 duration at .050 on a 110 LSA. That cam profile wakes the engine up off idle without becoming a handful in traffic, which is the sweet spot most LS swap builders are chasing.
The block is painted, the rotating assembly is balanced, and the front gear group is installed. You still need to source your own intake manifold, fuel injection or carb, distributor or coil packs, water pump, alternator, starter, and exhaust headers. Budget roughly two additional weekends for accessory installation and chassis plumbing if you are working solo.
Compatibility with LS Swap Chassis
This long block follows the classic GM Small Block bellhousing pattern, so it bolts to standard TH350, TH400, 700R4, and T56 transmissions with the right adapter. Motor mounts, oil pan, and accessory drive brackets need to match the chassis you are swapping into. For a factory-location LS swap, Holley or ICT Billet engine mount kits cover most applications, and the oil pan needs to match the front or rear sump configuration of your chassis.
ECM and wiring harness kits from companies like Speartech, Painless Performance, or Holley are usually required unless you are reusing the factory harness from the donor vehicle. Plan on a standalone ECU if you are putting this in a chassis that never had an LS engine from the factory.
Boost and Forced Induction Headroom
With factory hypereutectic pistons and a 10:1 compression ratio, this long block handles roughly 8-10 psi of boost on pump gas with conservative tuning. If you plan to push past that, upgrade to forged pistons and ARP main studs before adding boost. The cast iron block itself is robust enough for street strip duty but is not a dedicated drag racing block like the GM LSX or Dart LS Next.
For a daily driver street build, the 383 c.i. displacement gives you a much broader torque curve than a stock 350, which matters more than peak horsepower when you are pulling away from a stoplight with a heavy chassis behind you.
2. BluePrint 400 c.i. 500 HP GM Small Block Long Block — Best Value
BluePrint Engines GM Small Block Compatible 400 c.i. Engine – 500 HP – Long Block
500 HP output
400 c.i. displacement
LONGBLOCK config
419 lb package
Pros
- 500 HP from a 400 c.i. stroker for a competitive value tier
- Relatively lighter 419 lb package for a 400 c.i. engine
- Factory balanced rotating assembly and timed front gear
- GM Small Block bellhousing compatibility
Cons
- Limited public review history on this specific SKU
- Detailed valvetrain specs not published
If you want the most horsepower per dollar in the GM Small Block family, this 400 c.i. BluePrint long block is hard to beat. The 400 c.i. displacement comes from a longer stroke combined with a standard small block bore, and BluePrint uses this platform to push 500 HP out of the crate. The package weighs 419 pounds, which is meaningfully lighter than many of its 454 and 502 c.i. competitors, and that matters when you are wrestling the engine onto an engine stand or hoisting it into a tight engine bay.
The long block configuration arrives with the cylinder heads installed, the rotating assembly balanced, and the front gear group timed. Because it uses the standard GM Small Block bellhousing bolt pattern, it bolts to the same TH350, TH400, 700R4, and T56 transmissions as the smaller BluePrint engines. The major advantage over a smaller 383 build is the extra torque you get from the additional displacement, which is the single biggest factor in how an engine feels on the street.
You will still need to source the intake manifold, fuel system, ignition, water pump, alternator, starter, and exhaust. For a fuel injected LS-style swap, the Holley Sniper EFI Master Kit covers most of what you need in a single box. For a carbureted classic build, pair this with a Holley 770 street carb and a matched distributor.
Best Use Cases for a 400 c.i. Stroker
The 400 c.i. platform shines in heavier muscle cars like the Chevrolet Chevelle, Pontiac GTO, and older full-size cars where the extra torque matters more than peak horsepower numbers. It also works well in truck swaps where you want a noticeable jump over a stock 350 without stepping up to a Big Block.
For drag racing, the 400 c.i. stroker offers a strong torque curve right off the line and is a popular choice for street strip builds running a TH400 or 4L80E transmission. If your swap chassis is lighter and you want a more high-RPM feel, the 383 c.i. pickup in our Editor’s Choice spot is the better match.
Warranty and Build Sheet Documentation
BluePrint engines come with a build sheet documenting every component spec, and the company backs its long blocks with a limited warranty that covers hard internal parts. Reviewers on r/LSSwapTheWorld and project car forums report that BluePrint’s customer service is responsive when warranty claims come up, which is a meaningful advantage over some of the offshore remanufactured options.
Keep your build sheet and dyno sheet together with your receipts. If you ever need to file a warranty claim, the manufacturer will ask for both.
3. BluePrint 350 c.i. 341 HP Base Dressed Carbureted — Most Versatile
BluePrint Engines GM Small Block Compatible 350 c.i. Engine – 341 HP – Base Dressed – Carbureted
341 HP / 371 ft-lbs
9.2:1 compression
Carbureted
BluePrint aluminum heads
Pros
- Lower entry price point in the BluePrint lineup
- Carbureted for simpler classic GM install
- BluePrint aluminum cylinder heads and hypereutectic pistons
- 9.2:1 compression for daily pump gas operation
Cons
- Heavy at 534 pounds
- Single critical customer review published
- Lower displacement than the stroker options
The Budget Pick spot goes to the BluePrint 350 c.i. base dressed carbureted long block, which delivers 341 HP and 371 ft-lbs of torque at the lowest entry point of the GM Small Block long blocks on this list. The 350 c.i. displacement is the classic small block Chevy platform, and the carbureted fuel system means you do not need a separate fuel injection kit, ECM, or wiring harness to get the engine running. That alone saves several hundred dollars and a full weekend of wiring work.
The build uses BluePrint aluminum cylinder heads, a hydraulic roller cam with .477 intake and .471 exhaust lift, hypereutectic pistons, and a cast crankshaft at 3.480 inch stroke. The 9.2:1 compression ratio works on regular pump gas and gives you a friendly street character. If you are swapping into a classic truck or muscle car and want to keep the original carbureted fuel system, this is the straightforward path.
The package weighs 534 pounds, which is on the heavier side, but the engine dimensions (38 x 37 x 29 inches) match a standard GM Small Block, so it drops into most factory engine bays without modification.
What You Still Need to Buy
Even though this is a dressed long block, you still need to source your own distributor, ignition coil, spark plug wires, spark plugs, water pump, alternator, starter, exhaust headers, and fuel pump. Add roughly half a weekend to mount all of those accessories, plus another half day to set the initial timing and tune the carburetor.
If you are moving up from a tired original 350, the difference in how the engine fires on the first crank and settles into a smooth idle is dramatic. Most builders report the engine is ready for break-in within two days of the long block arriving.
Honest Review Caveat
The single published customer review for this SKU is critical, but the reviewer did not provide details that point to a specific component failure. With a sample size of one, the rating is not a reliable signal about long-term reliability. I would treat this as a starting point and verify your warranty documentation before installation.
BluePrint’s standard warranty covers hard internal parts, which is the coverage most builders actually need. Read the warranty card that ships with the engine before you start the install so you know exactly what is and is not covered.
4. BluePrint 383 c.i. 436 HP Deluxe Dressed Carbureted — Best for Classic GM Builds
BluePrint Engines GM Small Block Compatible 383 c.i. Engine – 436 HP – Deluxe Dressed – Carbureted
436 HP / 443 ft-lbs
10:1 compression
Deluxe Dressed
Carbureted
Pros
- Deluxe Dressed trim includes more accessories than the base version
- Same 436 HP and 443 ft-lbs output as the EFI version
- Carbureted fuel system for simpler classic install
- BluePrint aluminum cylinder heads and steel crankshaft
Cons
- No published customer reviews on this SKU
- Heavy at 475 pounds for the package
The Deluxe Dressed version of the 383 c.i. BluePrint long block is purpose-built for classic GM truck and muscle car swaps where you want a more complete accessory package from the start. The 436 HP and 443 ft-lbs output matches the EFI long block in our Editor’s Choice spot, but the carbureted fuel system and Deluxe Dressed trim save you from buying as many add-on parts separately.
Under the valve covers you get the same BluePrint aluminum cylinder heads, hydraulic roller cam with .544 intake and .555 exhaust lift, hypereutectic pistons, and steel crankshaft as the EFI version. The 10:1 compression ratio gives you strong mid-range torque, and the 383 c.i. displacement from the 3.750 inch stroke keeps the engine in its powerband across a wide RPM range.
The carbureted fuel system simplifies the swap into a chassis that was originally carbureted, because you can reuse your existing fuel line, fuel pump, and air cleaner mounting. Pair this with a Holley 670 street carb and a matched distributor and the engine will fire on the first or second crank.
What Deluxe Dressed Actually Includes
The Deluxe Dressed trim typically adds a cast aluminum intake manifold, a Holley or similar carburetor, an HEI distributor, ignition coil, spark plug wires, and sometimes a chrome dress-up kit. Check the exact contents against the product listing before you buy, because trim packages vary by SKU.
You still need to source your own water pump, alternator, starter, exhaust headers, and fuel pump. For a classic GM install, those are easy to find off-the-shelf parts, and reusing your existing accessories keeps the swap affordable.
Best Chassis Pairings
This long block pairs well with a 1967-1972 Chevrolet C10, 1968-1974 Chevrolet Nova, 1964-1972 Pontiac GTO, and 1970-1981 Chevrolet Camaro with a standard small block bellhousing. The 383 c.i. displacement gives you noticeably more torque than a stock 350, which is the single biggest improvement you can make to a classic truck or muscle car.
For drag racing or street strip duty, pair this long block with a TH400 transmission and a 3,500-3,800 RPM stall converter. The 383 stroker loves the higher stall and pulls hard all the way through the quarter mile.
5. BluePrint 347 c.i. 415 HP Ford Small Block Long Block — Best for Ford Swaps
BluePrint Engines Compatible with Ford Small Block, 347 c.i. Engine – 415 HP – Long Block
347 c.i. displacement
415 HP output
Small Block Ford fitment
Base crate engine
Pros
- Ford Small Block fitment for vintage Mustang and Ford truck swaps
- 415 HP from a 347 c.i. stroker platform
- Sold as a complete base crate engine for straightforward installs
- BluePrint brand reputation for build consistency
Cons
- No published customer reviews on this SKU
- Detailed specs like weight and dimensions are not listed
- Smaller community of Ford-specific builders compared to LS
The Ford side of the swap world is dominated by the Small Block Ford 289/302/351 family, and this BluePrint 347 c.i. long block delivers 415 HP in a platform that drops directly into a vintage Mustang, Ford F-100, or Fox body Mustang with the right motor mount and oil pan setup. The 347 c.i. displacement comes from a 3.400 inch stroke with a slightly overbored 302 block, which has been a popular stroker combination in the Ford swap community for decades.
BluePrint sells this engine as a complete base crate engine, meaning the cylinder heads, valvetrain, intake manifold (in carbureted form), and front gear group are installed. You will still need to add your own fuel injection or carb, ignition, water pump, alternator, starter, and exhaust.
The 415 HP output is a meaningful jump over a stock 302 c.i. engine, and the additional torque from the larger displacement gives you a much more responsive feel on the street. For a vintage Mustang restomod, this is one of the most popular displacement targets.
Ford Swap Chassis Compatibility
This long block fits the Ford Small Block bellhousing pattern, so it bolts to T5, TKO, TKX, AOD, C4, and C6 transmissions with the right bellhousing adapter. Vintage Mustang F-100 and Ranger swaps are the most common applications, and motor mount kits from companies like Concept One, Lentech, and Ron Francis Wiring cover the chassis-specific brackets.
For the oil pan, you typically need a front-sump pan for vintage Mustang applications and a rear-sump pan for older Ford trucks. Pick the pan before you order the long block so the pickup tube is the correct length.
ECM and Fuel Injection Considerations
If you are converting from a carbureted Ford to fuel injection, the easiest path is a Holley Sniper EFI Master Kit paired with a standalone ECU like a Holley Terminator X or an AEM Infinity. For a Coyote-style sequential injection setup, you will need a custom harness and a tune from a shop experienced with the Ford modular platform.
For carbureted builds, a Holley 670 or 770 street carb matched to an MSD or Pertronix distributor is the proven combination. The 347 stroker responds well to a mild performance cam in the 224-232 duration at .050 range.
6. BluePrint 302 c.i. 361 HP Ford Small Block Long Block — Best for 302 Builds
361 HP Ford Small Block Compatible 302 c.i. Long Block Engine by BluePrint Engines
361 HP / 334 ft-lbs
9.4:1 compression
4-bolt main cast iron
447 lb package
Pros
- High-strength cast iron block with 4-bolt mains and increased thickness
- BluePrint aluminum cylinder heads and hydraulic roller cam
- 9.4:1 compression for pump gas reliability
- 50oz front and rear balanced rotating assembly
Cons
- No published customer reviews on this SKU
- Larger packaging dimensions than some competitors
- Newer SKU with limited long-term community feedback
The BluePrint 302 c.i. long block takes the classic Ford 302 platform and adds the modern upgrades that make it a serious swap candidate. The high-strength cast iron block uses 4-bolt mains, increased deck and webbing thickness, and a priority main oiling system. That is a meaningful upgrade over a stock 302 block, which typically has only 2-bolt mains and thinner cylinder walls.
The build specs out at 361 HP and 334 ft-lbs of torque, with a 9.4:1 compression ratio that runs happily on premium pump gas. The hydraulic roller cam with .533 intake and .544 exhaust lift, combined with the BluePrint aluminum cylinder heads, gives you strong breathing through the mid-range and excellent throttle response. The 50oz front and rear balanced rotating assembly means the engine is smooth at highway RPM, which matters on a long road trip.
At 447 pounds and 48 x 43.5 x 40 inches in packaging, this long block is heavier than some of its GM counterparts but well within the limits of a standard engine hoist and stand.
Why a Built 302 Still Matters
Even with the Coyote and Godzilla modular engines on the market, the small block Ford 302 retains a massive swap community because it drops into vintage Mustang, F-100, Bronco, and Ranger chassis with no fabrication. A built 302 with 4-bolt mains and aluminum heads is one of the most reliable swap platforms available, and parts availability is excellent.
If you are doing a vintage Mustang restomod or a Ford truck swap and you want to keep the engine bay looking factory-correct, the 302 long block is the most straightforward path to modern power without giving up the classic engine profile.
Forced Induction Potential
The 4-bolt main cast iron block and hypereutectic pistons give you solid headroom for mild forced induction in the 6-8 psi range. For higher boost applications, upgrade to forged pistons and ARP main studs before adding the turbo or supercharger.
For a naturally aspirated street build, the 361 HP output is more than enough for a vintage Mustang or F-100 daily driver. If you want to push past 400 HP, step up to the 347 c.i. stroker pickup in our Ford swap slot.
7. BluePrint 454 c.i. 460 HP Big Block Chevy Dressed Crate Engine — Best Big Block
BluePrint Engines BPEBP454CTC 454 cu in. 460 HP Dressed Crate Engine – Big Block Chevy
454 c.i. displacement
460 HP output
Dressed crate engine
Big Block Chevy fitment
Pros
- Big Block Chevy 454 c.i. displacement with 460 HP output
- Dressed crate engine configuration for turnkey installation
- Classic muscle car and truck swap fitment
- BluePrint brand reputation for big block builds
Cons
- No published customer reviews on this SKU
- Item weight and detailed specs are not listed
- Premium price tier for the Big Block platform
For muscle car builders who want the unmistakable presence and torque of a Big Block Chevy, the BluePrint 454 c.i. dressed crate engine delivers 460 HP in a package that drops into the classic Chevelle, Camaro, Nova, and full-size Chevrolet chassis. The 454 c.i. displacement is the most iconic Big Block platform, and BluePrint’s dressed crate configuration means the cylinder heads, intake manifold, distributor, and front gear group arrive ready to install.
The 460 HP output from a 454 c.i. platform gives you a strong torque curve across the entire RPM range, which is the single biggest advantage of a Big Block over a small block stroker. If you are building a drag strip car, street strip muscle car, or heavy cruiser, the torque advantage is what you feel on every launch and every highway merge.
The dressed crate engine configuration saves you significant time compared to assembling a bare long block from individual components. The accessory brackets and intake manifold are installed, which means the engine is much closer to firing when you receive it.
Big Block vs Small Block Stroker
The question of whether to go with a Big Block or a small block stroker comes down to chassis weight, intended use, and aesthetic preference. A 454 c.i. Big Block delivers more torque than a 383 c.i. small block stroker, but it also weighs more and requires more room in the engine bay. For a heavier chassis like a 1968-1972 Chevelle or a 1966-1970 full-size Chevrolet, the Big Block is the natural fit.
For a lighter chassis like a 1968-1974 Nova or a third-generation Camaro, a small block stroker may be a better match for handling balance and front-to-rear weight distribution.
What Big Block Swaps Typically Need
Big Block swaps usually require motor mount swaps, oil pan configuration changes (most small block pans do not fit), and sometimes hood clearance modifications. The standard Big Block bellhousing pattern matches TH400 and Muncie transmissions, so transmission swaps are usually straightforward.
Plan on upgrading the cooling system and fuel system to match the higher torque output. A larger radiator, electric fan, and a higher capacity fuel pump are common upgrades.
8. GM Performance Parts 6.2L LS3 430 HP Crate Engine — Best OEM LS3
GM PERFORMANCE PARTS 19301326 Crate Engine – 6.2L LS3 430HP
6.2L LS3
430 HP output
Genuine GM crate
465 lb package
Pros
- OEM GM Performance Parts LS3 6.2L crate engine rated at 430 HP
- Genuine factory crate engine build with OEM specs
- Drop-in for any LS3-compatible swap chassis
- Reputation for factory-grade reliability
Cons
- Single critical customer review on record
- Pricier than many aftermarket long block options
- Heavy at 465 pounds
If you want a factory-built LS3 6.2L with the OEM GM Performance Parts pedigree, this crate engine is the genuine article. The 6.2L LS3 platform is one of the most popular LS swap engines ever produced, originally found in the 2008-2013 Chevrolet Corvette and the 2010-2015 Camaro SS. The 430 HP output comes directly from the factory tune, and the engine is built to OEM specifications with factory quality control.
At 465 pounds and 42 x 38 x 31 inches in packaging, this crate engine is a direct fit for any LS3-compatible swap chassis. The major advantage of going OEM is the documentation, parts availability, and the knowledge that the engine was assembled to factory tolerances. For purists and builders who want factory-grade reliability, that is hard to beat.
The crate engine configuration includes the throttle body, intake manifold, fuel injectors, fuel rail, ignition coils, and harmonic balancer. You will still need to source your own engine control module, wiring harness, sensors, exhaust, and accessory drive.
Why Pay More for an OEM Crate Engine
The price premium on a GM Performance Parts crate engine versus an aftermarket long block comes down to three things: factory documentation, OEM parts availability, and the long-term reliability of an engine built to original factory tolerances. For projects where you want absolute certainty about the build quality and you need factory-grade support, the OEM crate engine is the right choice.
Aftermarket long blocks from brands like BluePrint, Smeding, and TSP offer better value per horsepower and more customization options, but they do not have the OEM pedigree.
LS3 Swap Chassis Pairing
This LS3 crate engine drops into any LS3 swap application including the fifth-generation Camaro SS, fourth-generation F-body LS swaps, C10 trucks, classic muscle cars, and hot rods. The LS3 bellhousing bolt pattern matches the T56, TR6060, and 4L70E transmissions commonly used in GM performance builds.
For a C10 swap, the Holley Hooker Blackheart LS swap engine mount kit and a Holley oil pan cover the chassis-specific brackets and oil pan configuration. Wiring harness kits from Speartech and Painless Performance plug directly into the GM Performance Parts LS3 sensors.
9. BluePrint 350 c.i. 390 HP GM Small Block Long Block — Top Rated GM 350
390 HP Long Block 350 c.i. Engine Compatible with GM Small Block by Blueprint Engines
390 HP / 410 ft-lbs
9.2:1 compression
Aluminum heads
Hypereutectic pistons
Pros
- 390 HP from a 350 c.i. platform with strong 410 ft-lbs torque
- Aluminum cylinder heads for improved breathing
- Hydraulic roller camshaft for modern valvetrain reliability
- 9.2:1 compression for pump gas operation
Cons
- No published customer reviews on this SKU
- Weight and dimensions not listed in product data
- Newer SKU with limited long-term community feedback
The 350 c.i. small block Chevy is the most popular swap engine in the world, and this BluePrint long block delivers 390 HP and 410 ft-lbs of torque in a package built for modern reliability. The aluminum cylinder heads combined with a hydraulic roller camshaft give you the breathing and valvetrain strength that the original small block never had from the factory.
The 9.2:1 compression ratio runs on regular pump gas, and the hypereutectic pistons give you the durability needed for daily driving and weekend cruising. Compared to a stock 350, this BluePrint long block delivers roughly 30-40% more horsepower and a noticeably broader torque curve, which is what you actually feel when you drive the car.
The build follows the classic GM Small Block bellhousing pattern, so it bolts to the same transmissions as a stock 350. Motor mounts, oil pan, and accessory drive brackets need to match your specific swap chassis.
Why the 350 c.i. Platform Still Wins
For three decades, the 350 c.i. small block has been the default swap engine in the GM performance world, and it remains so because parts availability is unmatched, the swap community is enormous, and the platform responds well to modifications. If you are doing your first engine swap, the 350 is the most forgiving platform to learn on.
The aftermarket support is so deep that almost any problem you encounter has been solved by another builder before you, and the forum archives on LS1Tech, CorvetteForum, and countless project car sites document every swap scenario.
Best Chassis for a 350 Long Block
This long block fits the same chassis as the other GM Small Block engines on this list, including C10 trucks, first and second-generation Camaros, Novas, Vegas, and full-size Chevrolet cars. For first-time builders, the 350 is the lowest-risk swap because every part you need is widely available and well-documented.
For drag racing, pair this with a TH400 transmission and a 3,500 RPM stall converter. For street driving, a 700R4 or 4L60E overdrive transmission gives you better highway fuel economy and lower RPM at cruising speed.
10. GM Parts 350 Crate Engine for GM Truck — Best for Truck Swaps
GM Parts 12530282 Crate Engine for GM Truck 350
GM Truck 350 fitment
OEM Performance Parts
474 lb package
Long block / crate engine
Pros
- Genuine GM Performance Parts crate engine for GM Truck 350 swap
- OEM factory build quality and documentation
- Compact packaging dimensions fit standard GM truck engine bays
- Strong aftermarket support for GM truck swap applications
Cons
- No published customer reviews on this SKU
- Detailed horsepower and torque specs not listed
- Older SKU with potentially dated product photos
If you are swapping a tired original 350 into a 1973-1987 Chevrolet C10, GMC C15, or earlier GM truck, this GM Performance Parts crate engine is the genuine factory replacement. The 350 c.i. small block was the standard engine in GM trucks for decades, and the OEM crate engine configuration means it drops into the factory engine mounts with no fabrication.
At 474 pounds and 30.25 x 28.5 x 26.75 inches in packaging, this crate engine is compact enough to fit through the engine bay opening of most GM trucks without modification. The OEM Performance Parts build means the engine follows factory specifications and is backed by GM’s documentation standards.
You will still need to source your own fuel system, ignition, exhaust, and accessory drive components. For a factory-style replacement, reusing your existing accessories is the most straightforward path.
GM Truck Swap Specifics
GM trucks from 1973 to 1987 used the standard small block Chevy bellhousing pattern and the standard GM motor mount configuration. The crate engine bolts to the factory TH350, TH400, SM465, or later 700R4 transmissions with no adapter needed.
For the oil pan, the GM truck sump configuration is different from the car configuration, so you typically need a truck-sump pan or a swap pan from Holley or Hooker. Plan on this before you order the long block.
When to Choose OEM Over Aftermarket
If you are restoring a GM truck to factory specifications or you want absolute certainty about the engine build quality, the OEM crate engine is the right choice. If you are building a high-performance street or drag strip truck, an aftermarket long block with more horsepower and a stronger rotating assembly is the better value.
For a daily driver truck that needs a reliable replacement engine, this OEM crate engine offers the right balance of factory quality and straightforward installation.
What to Look for in a Long Block for Engine Swaps
A long block is the right choice for most engine swaps because it gives you a professionally balanced, dyno-tested rotating assembly with cylinder heads and valvetrain installed, while costing noticeably less than a complete drop-in crate engine. The key buying criteria below cover what actually matters when you are deciding between the ten long blocks above.
Engine Family and Swap Chassis Compatibility
The first and most important decision is which engine family matches your swap chassis. LS and LT engines from General Motors dominate the modern swap scene thanks to their compact size, light weight, and massive aftermarket support. Ford Small Block engines are the natural fit for vintage Mustang, F-100, and Bronco swaps. Big Block Chevy engines are the choice for classic muscle car restomods where torque and presence matter more than rev range.
Before you order any long block, confirm the bellhousing bolt pattern matches your transmission, the motor mount pattern matches your chassis, and the oil pan configuration fits your engine bay. The wrong combination of any of these three can turn a simple swap into a fabrication project.
Block Strength and Material
Cast iron blocks are heavier but more durable and easier to repair if cracked. Aluminum blocks are lighter and dissipate heat better, but they are typically scrap if the cylinder walls are damaged. For most street and street strip applications, a cast iron block is the more practical choice because parts availability is wider and repairs are easier.
If you are chasing maximum power from forced induction, look for aftermarket castings like the GM LSX, Dart LS Next, or Chevrolet Performance SHP designation. These have thicker cylinder walls, more head bolt threads, and the structural integrity to handle higher boost pressures.
Compression Ratio and Intended Use
Compression ratio is the single biggest factor in how an engine behaves on the street and what fuel it requires. A 9.0:1 to 10.5:1 compression ratio runs on premium pump gas and supports mild forced induction. A 11.0:1 or higher ratio requires race gas or E85 and is best suited for naturally aspirated race builds.
For a daily driver or weekend cruiser, stick with the 9.0:1 to 10.5:1 range. For a dedicated race car, the higher compression makes sense. For a forced induction build, stay at 9.0:1 or below to keep detonation under control.
Warranty Terms and What They Actually Cover
Long block warranties typically cover hard internal parts like the block, crankshaft, connecting rods, pistons, and cylinder heads. They usually do not cover accessories like the water pump, alternator, fuel injectors, or sensors. Read the warranty card before you buy so you know exactly what is and is not covered.
Warranty terms vary widely. Some brands offer 3-year unlimited mileage, others offer 5-year capped mileage, and others offer mileage-tiered coverage that drops after a certain threshold. Forum users on r/LSSwapTheWorld consistently rate BluePrint, Smeding, and TSP as having the most honored warranty claims in the industry.
What You Still Need to Buy
A long block is not a turnkey drop-in engine. You will still need to source your own intake manifold, fuel injection or carburetor, ignition system, water pump, alternator, starter, exhaust headers, and engine control module. Budget a portion of the long block cost for these accessories, plus extra if you are paying a shop to install them.
For a basic carbureted classic build, the accessory list is shorter and the parts are cheaper. For a modern LS swap with fuel injection and a standalone ECU, the accessory list is longer and the parts are more expensive but the result is a much more refined driving experience.
Common Long Block Swap Mistakes to Avoid
The most common mistake is ordering a long block without confirming the oil pan configuration matches the chassis. Front sump, rear sump, and truck sump pans are not interchangeable, and the wrong pan means the engine will not clear the steering linkage or the chassis crossmember.
The second most common mistake is underestimating the wiring harness and ECU work for a fuel injected swap. Plan on at least 40-60 hours of wiring and tuning time for a standalone ECU installation, and budget for professional tuning if you are not experienced with the platform.
The third mistake is reusing old motor mounts and accessory brackets that have been stressed by a worn-out engine. Once you have the engine out, replace the motor mounts, the accessory brackets, and any worn hardware. The cost is small compared to the labor of having to do it again later.
Forced Induction Compatibility Per Block
Not every long block handles boost equally. Stock cast iron blocks with factory hypereutectic pistons typically handle 6-8 psi of boost on pump gas with conservative tuning. Aftermarket castings like the GM LSX, Dart LS Next, and Chevrolet Performance SHP handle 15-20+ psi with proper internal upgrades.
For a turbo or supercharger build, plan on upgrading to forged pistons, ARP main studs, and a stronger head gasket before adding boost. The cost of those upgrades is small compared to the cost of replacing a failed block.
Build Time and Lead Time Expectations
Remanufactured long blocks typically require a few weeks of build time because the manufacturer is assembling them to order with the components you specify.
If your swap is time-sensitive, the crate engine or dressed long block route is the faster option. If you have flexibility and you want a specific component combination, the custom remanufactured long block is worth the wait.
Frequently Asked Questions
Which is better, long block or short block?
A long block is better for most engine swaps because it includes the cylinder heads, camshaft, and valvetrain pre-installed and dyno-tested by the manufacturer. A short block only includes the block, crankshaft, connecting rods, and pistons, leaving you to assemble and seal the heads yourself, which adds significant labor and risk of head gasket failure. The short block is cheaper and lets you choose your own heads, but the long block is the faster and more reliable path for most builders.
What is the strongest type of engine block?
The strongest type of engine block for forced induction builds is an aftermarket cast iron or aluminum billet block with four-bolt mains, thick cylinder walls, and additional head bolt threads. Castings like the GM LSX, dart LS Next, Chevrolet Performance SHP, and World Products Windsor Sr. are designed for 15-20+ psi of boost. Stock cast iron blocks handle 6-8 psi reliably but should be upgraded for higher boost.
What is the best engine for an engine swap?
The best engine for an engine swap depends on your chassis and intended use. For most GM swaps, the LS3 6.2L is the most popular because it combines 430 HP from the factory with a compact package and massive aftermarket support. For Ford swaps, the 302 or 347 c.i. small block is the most common because it drops into vintage Mustang and F-100 chassis with no fabrication. For Big Block builds, the 454 c.i. Chevy is the iconic choice for muscle car restomods.
Which crate engine is the most reliable?
The most reliable crate engine for most builders is a GM Performance Parts LS3 6.2L because it is built to factory specifications with OEM quality control. Among aftermarket long blocks, BluePrint, Smeding Performance, and Texas Speed and Performance are consistently rated as the most reliable by community feedback on r/LSSwapTheWorld and project car forums. Jasper Engines is rated as having mixed reviews and ATK engines are generally solid but more racing-oriented.
How long does it take to install a long block?
A long block swap typically takes 40-80 hours of labor for a first-time builder working solo. Experienced shops can complete a basic LS swap in 30-40 hours, and a more complex fuel injected swap with standalone ECU and custom harness can take 80-120 hours. The actual engine swap is just one part of the work; you also need to plan for wiring harness fabrication, fuel system installation, exhaust fabrication, and initial tuning.
Final Verdict
For most engine swap builds in 2026, the BluePrint 383 c.i. 436 HP GM Small Block long block in the Editor’s Choice spot is the best balance of horsepower, build quality, and value. It drops into the most popular swap chassis, handles mild forced induction, and comes from a brand with strong warranty support and community reputation. If you are on a tighter budget, the BluePrint 350 c.i. base dressed carbureted long block is the most affordable path to a reliable swap. For Ford swaps, the BluePrint 347 c.i. or 302 c.i. long blocks are the right fit, and for muscle car restomods, the BluePrint 454 c.i. Big Block delivers the torque and presence the chassis was built for.
Whichever long block you choose, confirm the bellhousing pattern, motor mount pattern, and oil pan configuration match your chassis before you order, and budget for the accessories you will still need to source separately. The ten long blocks above are the best options available right now for the most popular swap platforms. Pick the one that matches your chassis, your budget, and your horsepower target, and you will end up with a swap that fires on the first or second crank and runs reliably for years.