A strong choice for a 400-style crank in a 350 block delivers a compatible 3.750-inch stroke and matches the engine’s rear-seal, balance, and connecting-rod setup. The Scat Crankshafts 4-400-3750-5700 is a compelling starting point for builders seeking a forged 4340 crank listed for a 350 with a 2-piece rear seal and 5.700-inch rods. This roundup also includes cast-steel and iron 3.750-inch options, plus longer-stroke alternatives and a stock-stroke crank for comparison.
Those differences matter: a crank’s stroke alone does not establish that it fits a particular block or rotating assembly. Check the seal configuration, balance requirements, rod length, journal dimensions, and clearances against your build before ordering.
The product details provide useful starting specifications, but do not confirm every compatibility requirement.
The Scat Crankshafts 4-400-3750-5700 leads for a 400-style crank in a 350 block because its listed details combine a 3.750-inch stroke with forged 4340 construction, a 350 2-piece rear seal, 5.700-inch rod length, and 2.100-inch rod journals. That makes its listed configuration especially relevant to the search. Confirm your block, seal, balance, rods, and clearances before purchase; the product listing does not establish universal fitment for every 350 build.
Our Top Picks
Best OverallIts forged 4340 construction and 3.750-inch stroke pair with a listed 350 2-piece rear seal, 5.700-inch rods, and 2.100-inch rod journals.
View on AmazonForged 350 OptionThis forged 4340 small-block Chevrolet crank has a 3.750-inch stroke and a 350-specific model designation, though the supplied details omit seal and balance specifications.
View on Amazon
Cast Steel OptionThe 3.750-inch cast-steel crank is identified for Chevrolet 400, with a 2-piece rear seal, external balance, and 5.7-inch rod length.
View on Amazon- One-Piece Seal Scat Pro Comp 9000
- Longer Stroke Eagle 435040006000
Compare These 400-Style Crank Options
| # | Product | Dimensions | Weight | Buy |
|---|---|---|---|---|
| 1 | 1. Scat 4-400-3750-5700Best Overall | 13.78 x 25.59 x 13.78 in | 77 lb | View on Amazon |
| 2 | 2. Scat 4-350-3750-5700Forged 350 Option | 25.6 x 9.1 x 9.3 in | 57.4 lb | View on Amazon |
| 3 | 3. Eagle 104003750Cast Steel Option | — | 24.5 lb | View on Amazon |
| 4 |  4. Scat Pro Comp 9000One-Piece Seal | 13.78 x 25.59 x 13.78 in | 3.52 oz | View on Amazon |
| 5 |  5. Eagle 435040006000Longer Stroke | 28 x 9 x 8 in | 63 lb | View on Amazon |
| 6 |  6. Eagle Chevrolet 400Long-stroke forged-steel builds | — | 60 lb | View on Amazon |
| 7 | 7. Scat Pro Stock 9000Stock-stroke iron replacements | 27.68 x 10.11 x 7.82 in | 53 lb | View on Amazon |
Detailed Reviews: Best 400 Crank For 350 Block
#1 · Best Overall
1. Scat 4-400-3750-5700
- Dimensions: 13.78 x 25.59 x 13.78 in
- Weight: 77 lb
Best for: Forged 3.75-inch 2-piece-seal builds.
Why it ranks #1: Its forged 4340 construction and 3.750-inch stroke pair with a listed 350 2-piece rear seal, 5.700-inch rods, and 2.100-inch rod journals.
A forged 4340 crankshaft with a 3.750-inch stroke gives this Scat a clear role in a small-block Chevy 400-style build. Its listed 5.700-inch rod length and 2.100-inch rod journal make the intended rotating-assembly dimensions explicit for planning parts and machine work.
The 3.750-inch stroke and 5.700-inch rod length provide the core dimensions for matching rods and planning the assembly. Scat specifies a 2.100-inch rod journal, another useful measurement when selecting compatible components. Its 2-piece rear-seal configuration identifies the block-seal arrangement the build needs, while forged 4340 construction and standard weight distinguish this crank from the cast and lightweight options in the group. Check the rest of the rotating assembly against those stated dimensions before installation.
- Forged 4340 construction
- 3.750-inch stroke
- 5.700-inch rod length specified
- 2.100-inch rod journal and 2-piece rear seal specified
- The listed configuration is for a 2-piece rear-seal block.
Skip it if you need a 1-piece rear seal; Scat's Pro Comp Lightweight 9000 Series 3.750-inch crank lists that seal configuration.
Choose this Scat for a small-block Chevy build targeting a 3.750-inch stroke, 5.700-inch rods, and a 2-piece rear seal. Its stated 2.100-inch rod journal helps define parts selection, but the assembly must match those dimensions.
Full product details
| Brand | Scat Crankshafts |
|---|---|
| Item Weight | 77 pounds |
| Item model number | 4-400-3750-5700 |
| Manufacturer | Scat Crankshafts |
| Part Number | 440037505700 |
| Dimensions | 13.78 x 25.59 x 13.78 inches |
Listed on Amazon as: Scat Crankshafts 4-400-3750-5700 Forged 4340 Crankshaft for Small Block Chevrolet
View on Amazon#2 · Forged 350 Option
2. Scat 4-350-3750-5700
- Dimensions: 25.6 x 9.1 x 9.3 in
- Weight: 57.4 lb
Best for: Forged 3.75-inch stroke builds.
Why it ranks #2: This forged 4340 small-block Chevrolet crank has a 3.750-inch stroke and a 350-specific model designation, though the supplied details omit seal and balance specifications.
Scat specifies forged 4340 construction and a 3.750-inch stroke for this small-block Chevrolet crank, giving buyers two concrete starting points for a 400-style build. Its title identifies the 4-350-3750-5700 model, while the supplied details leave seal and balance configuration unstated.
The 3.750-inch stroke makes this crank relevant to builders targeting that stroke in a small-block Chevrolet, and forged 4340 construction distinguishes its material from the iron and cast-steel choices here. Scat's listed product dimensions and 57.4-pound item weight provide handling and storage context for receiving and preparing the part. The supplied product facts do not specify rear-seal type, balance arrangement, rod length, or journal size, so those details need separate confirmation before the assembly plan is finalized.
- 3.750-inch stroke
- Forged 4340 construction
- Small-block Chevrolet application stated
- Product dimensions and item weight supplied
- Rear-seal type and balance arrangement are not specified in the supplied details.
Skip it if you need a stated 2-piece rear seal and 5.700-inch rod length; Scat Crankshafts 4-400-3750-5700 lists both.
Consider this Scat for a small-block Chevrolet build targeting a 3.750-inch stroke and forged 4340 construction. Since seal type, balance arrangement, and rod dimensions are not stated, those details matter before committing to the assembly.
Full product details
| Brand | Scat Crankshafts |
|---|---|
| Item Weight | 57.4 pounds |
| Item model number | 4-350-3750-5700 |
| Manufacturer | Scat Crankshafts |
| Part Number | 435037505700 |
| Dimensions | 25.6 x 9.1 x 9.3 inches |
Listed on Amazon as: Scat Crankshafts 4-350-3750-5700 Forged 4340 Crankshaft for Small Block Chevrolet
View on Amazon#3 · Cast Steel Option
3. Eagle 104003750
- Weight: 24.5 lb
Best for: Cast-steel external-balance builds.
Why it ranks #3: The 3.750-inch cast-steel crank is identified for Chevrolet 400, with a 2-piece rear seal, external balance, and 5.7-inch rod length.
Eagle pairs a 3.750-inch stroke with cast steel and an external-balance specification, making this crank a dimension-specific option for a small-block Chevy 400 build. It also lists a 2-piece early-style rear seal and a 5.7-inch rod length, helping buyers identify the intended assembly configuration.
The 3.750-inch stroke and 5.7-inch rod-length specification give builders concrete dimensions to use when matching the crank to rods and the rest of the rotating assembly. Eagle also identifies external balance and a 1870 bobweight, which informs balance planning rather than leaving that setup unspecified. The early-style 2-piece rear seal is another compatibility detail for the block. Its cast-steel construction is a key distinction from the forged crank options in this roundup.
- 3.750-inch stroke
- Cast-steel construction
- External balance with 1870 bobweight specified
- Early-style 2-piece rear seal and 5.7-inch rod length listed
- This is cast steel, not a forged-steel crankshaft.
Skip it if you want a forged 3.750-inch crank; Scat Crankshafts 4-400-3750-5700 lists forged 4340 construction.
This Eagle suits builders seeking a cast-steel 3.750-inch small-block Chevy crank with external balance and an early-style 2-piece seal. Its 5.7-inch rod specification narrows the setup; verify the complete rotating assembly matches.
Full product details
| Brand | Eagle |
|---|---|
| Item Weight | 24.5 pounds |
| Item model number | 5.1101G |
| Manufacturer | Eagle Specialty Products |
| Part Number | 104003750 |
| Model | JEGS |
Listed on Amazon as: EAGLE SPCLTY Eagle Specialty Products 104003750 3.75" Cast Steel Crankshaft for Small Block Chevy
View on Amazon#4 · One-Piece Seal
4. Scat Pro Comp 9000
- Dimensions: 13.78 x 25.59 x 13.78 in
- Weight: 3.52 oz
Best for: Lightweight 1-piece-seal setups.
Why it ranks #4: Its 3.750-inch stroke suits a stroker direction, and the listing specifies external balance and a 1-piece seal, but identifies it as iron.
Scat combines a 3.750-inch stroke with a 1-piece seal and external balance in this Pro Comp Lightweight 9000 Series iron crank. Those configuration details make it a distinct option for small-block Chevy builders whose block and rotating assembly call for that seal and balance arrangement.
The 3.750-inch stroke matches the stroke used by several 400-style small-block Chevy builds, while the 1-piece seal identifies the rear-seal configuration the block must accommodate. Scat also specifies external balance, a consequential detail for planning the matching rotating assembly and balance work. Iron construction and the Pro Comp Lightweight 9000 Series name identify the product line, but the supplied facts do not provide a numeric weight comparison or rod dimensions.
- 3.750-inch stroke
- 1-piece seal specified
- External balance specified
- Iron Pro Comp Lightweight 9000 Series construction
- The listed configuration uses external balance, not internal balance.
Skip it if you need internal balance; Scat Crankshafts Pro Stock 9000 Series 3.480-inch crank specifies internal balance and a 2-piece seal.
This Scat is for a small-block Chevy build needing a 3.750-inch stroke, 1-piece seal, and external balance. Confirm the block and rotating assembly use those exact arrangements; the supplied listing does not state rod dimensions.
Full product details
| Brand | Scat Crankshafts |
|---|---|
| Item Weight | 3.52 ounces |
| Item model number | 9-350-3750-5700-L |
| Manufacturer | Scat Crankshafts |
| Part Number | 935037505700L |
| Model | Crankshaft |
| Dimensions | 13.78 x 25.59 x 13.78 inches |
Listed on Amazon as: Scat CrankshaftsCrankshaft, Pro Comp Lightweight 9000 Series, 3.750 in Stroke, External Balance, Iron, 1 Piece Seal, Small Block Chevy, Each
View on Amazon#5 · Longer Stroke
5. Eagle 435040006000
- Dimensions: 28 x 9 x 8 in
- Weight: 63 lb
Best for: Forged 4-inch stroke assemblies.
Why it ranks #5: This forged 4340 crank offers a 4.000-inch stroke and internal balance, but its listed rod length is 6.000 inches or longer.
A 4.000-inch stroke sets this Eagle apart from the 3.750-inch options, while forged 4340 steel gives it a clear place in a longer-stroke small-block Chevy build. Its listed 6.000-inch-or-longer rod length and internal balance define important assembly choices up front.
The 4.000-inch stroke gives builders a different stroke dimension from a conventional 3.750-inch 400-style choice, so it calls for deliberate planning of the full rotating assembly. Eagle specifies rods 6.000 inches or longer and a 2.100-inch rod journal, useful dimensions when selecting connecting rods. The 2-piece early-style rear seal identifies the seal arrangement, and internal balance plus an 1855 bobweight inform balancing work. Forged 4340 construction completes its stated specification profile.
- 4.000-inch stroke
- Forged 4340 steel construction
- Internal balance with 1855 bobweight specified
- 2.100-inch rod journal and 2-piece early-style seal listed
- Its 4.000-inch stroke is longer than the 3.750-inch stroke commonly sought for this roundup.
Skip it if you need a 3.750-inch stroke; Eagle's 104003750 cast-steel crank lists that stroke and a 5.7-inch rod length.
Pick this Eagle for a small-block Chevy build planned around a 4.000-inch stroke, internal balance, and rods at least 6.000 inches long. It is not a direct choice for a 3.750-inch stroke combination.
Full product details
| Brand | Eagle |
|---|---|
| Item Weight | 63 pounds |
| Item model number | 4.5110R |
| Manufacturer | Eagle Specialty Products |
| Part Number | 435040006000 |
| Dimensions | 28 x 9 x 8 inches |
| Additional Information | Important Information Proposition 65 Warning for California Consumers WARNING: This product can expose you to chemicals including styrene which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov |
Listed on Amazon as: Eagle Specialty Products 435040006000 4" Stroke 4340 Forged Crankshaft for Small Block Chevy
View on Amazon#6
6. Eagle Chevrolet 400
- Weight: 60 lb
Best for: Long-stroke forged-steel builds.
Why it ranks #6: The forged-steel crank is identified as a Chevrolet 400 part and has a 4.125-inch stroke, but the supplied details do not list seal or rod dimensions.
Eagle's 4.125-inch stroke is the largest listed here, making this forged-steel crank a specific option for a small-block Chevy build planned around that longer stroke. Internal balance and a 2-piece seal are also stated, so builders can weigh the configuration before assembling the rotating package.
The 4.125-inch stroke calls for a build planned around that dimension, rather than a standard 3.750-inch stroke combination. Eagle lists forged steel and internal balance, connecting material and balancing choices to the assembly plan without implying a performance rating. The 2-piece seal specification gives another concrete block-configuration consideration. Because the supplied details do not state rod length or rod-journal size, buyers should base their parts plan on confirmed dimensions beyond those listed here.
- 4.125-inch stroke
- Forged-steel construction
- Internal balance specified
- 2-piece seal specified
- The listed stroke is 4.125 inches, not the common 3.750-inch choice.
Skip it if you need a 3.750-inch stroke; Eagle's 104003750 cast-steel small-block Chevy crank specifies 3.750 inches.
Choose this Eagle for a small-block Chevy project deliberately planned around a 4.125-inch stroke, forged steel, internal balance, and a 2-piece seal. Its supplied details omit rod dimensions, so confirm those from appropriate build documentation.
Full product details
| Brand | Eagle |
|---|---|
| Included Components | Crankshafts |
| Item Weight | 60 pounds |
| Manufacturer | Eagle |
| Model | 440041256000 |
| Warranty Description | Manufacturer Warranty |
| Additional Information | Important Information Proposition 65 Warning for California Consumers WARNING: This product can expose you to chemicals including styrene which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov |
Listed on Amazon as: Eagle Chevrolet 400 Forged Crankshaft
View on Amazon#7
7. Scat Pro Stock 9000
- Dimensions: 27.68 x 10.11 x 7.82 in
- Weight: 53 lb
Best for: Stock-stroke iron replacements.
Why it ranks #7: Its 3.480-inch stroke is a stock-stroke configuration rather than the 3.750-inch 400-style stroke sought for this 350-block build.
Its 3.480-inch stroke makes this Scat Pro Stock 9000 Series crank a stock-stroke-style choice rather than a 400-stroke option. The iron construction, internal balance, and 2-piece seal are named plainly, helping builders assess whether its configuration matches a small-block Chevy replacement or rebuild.
The 3.480-inch stroke is the central fit consideration: it distinguishes this crank from the longer-stroke choices intended for a 400-style small-block Chevy assembly. Scat lists internal balance, which gives the builder a defined balance arrangement to plan around, and a 2-piece seal for matching the block's rear-seal configuration. Its iron construction is also explicit, allowing a straightforward comparison with forged or cast-steel alternatives without assuming an unstated strength rating.
- 3.480-inch stroke
- Internal balance specified
- Iron construction
- 2-piece seal specified
- The 3.480-inch stroke is not a 3.750-inch 400-stroke configuration.
Skip it if you need a 3.750-inch stroke; Scat Crankshafts 4-350-3750-5700 lists that stroke and forged 4340 construction.
This Scat fits buyers rebuilding a small-block Chevy around a 3.480-inch stroke, internal balance, and a 2-piece seal. Skip it for a 400-stroke target: its stated stroke is shorter than the 3.750-inch options.
Full product details
| Brand | Scat Crankshafts |
|---|---|
| Item Weight | 53 pounds |
| Item model number | 9-10442 |
| Manufacturer | Scat Crankshafts |
| Part Number | 910442 |
| Model | Crankshaft |
| Dimensions | 27.68 x 10.11 x 7.82 inches |
Listed on Amazon as: Scat Crankshafts Scat CrankshaftsCrankshaft, Pro Stock 9000 Series, 3.480 in Stroke, Internal Balance, Iron, 2 Piece Seal, Small Block Chevy, Each
View on AmazonWhy stroke alone does not establish 350-block fit
A 3.750-inch stroke does not by itself confirm that a crank will fit a particular 350 block or its rotating assembly. The listings show how much else can vary at that stroke: the Scat 4-400-3750-5700 specifies a 350 2-piece rear seal, 5.700-inch rods, and 2.100-inch rod journals, while the Eagle 104003750 lists a 2-piece seal, external balance, and 5.7-inch rods. The Scat Pro Comp 9000 instead specifies a 1-piece seal and external balance, and the Scat 4-350-3750-5700 listing does not state seal or balance details.
Treat those gaps as unresolved, not as evidence that the parts match. A compatibility trap is ordering by the phrase “400 crank” or stroke alone without confirming the block’s seal arrangement, journal dimensions, balance plan, and intended rods.
The supplied data does not establish required block clearancing or confirm fitment in a specific engine.
The trade-off between stroke and rod setup
A longer stroke changes the build target, so compare the crank’s stated rod requirements rather than treating every stroker option as interchangeable. Several choices here list a 3.750-inch stroke: the Scat 4-400-3750-5700 specifies 5.700-inch rods, and the Eagle 104003750 specifies a 5.7-inch rod length. The Eagle 435040006000 steps up to a 4.000-inch stroke and specifies 6.000-inch or longer rods; the Eagle Chevrolet 400 lists a 4.125-inch stroke but supplies no rod-length detail.
Those figures help narrow the shortlist, but they do not prove that a particular rod, piston, or block combination clears. A builder retaining a 5.7-inch rod plan can focus first on the 3.750-inch listings.
Someone planning a longer rod or greater stroke should verify the full rotating assembly and machine-work needs before choosing a crank.
How to Choose a 400-Style Crank for a 350
Stroke and rod length
Start with the stroke your rotating assembly is designed to use, then confirm the corresponding rod length. The listed options span 3.480 inches on the Scat Pro Stock 9000, 3.750 inches on four products, 4.000 inches on the Eagle 435040006000, and 4.125 inches on the Eagle Chevrolet The Scat 4-400-3750-5700 lists a 5.700-inch rod length, the Eagle 104003750 lists 5.7 inches, and the Eagle 435040006000 specifies 6.000 inches or longer.
A buyer targeting the common 3.750-inch direction should focus on those configurations; a longer-stroke plan requires matching rods and validating the complete assembly rather than assuming compatibility from stroke alone.
Material and construction
Choose crank material in the context of your build and the exact part specifications, not from the product title alone. The Scat 4-400-3750-5700 and Scat 4-350-3750-5700 are listed as forged 4340, as are the Eagle 435040006000’s forged 4340 specifications. The Eagle 104003750 is described as cast steel, while the Scat Pro Stock 9000 and Scat Pro Comp 9000 are listed as iron.
The Eagle Chevrolet 400 is described as forged steel. These descriptions let you distinguish construction types, but the supplied data does not provide comparable load ratings or intended power limits.
Buyers with a specific performance target should confirm the manufacturer’s application guidance; those choosing among listed specs can first narrow by stroke, seal, and balance.
Seal and balance configuration
Match the crank’s rear-seal and balance configuration to the engine and the rest of the rotating assembly. The Scat 4-400-3750-5700 is described for a 350 with a 2-piece rear seal, and the Eagle 104003750 specifies a 2-piece seal and external balance. The Scat Pro Comp 9000 lists a 1-piece seal and external balance, while the Eagle 435040006000 specifies a 2-piece rear seal and internal balance.
Seal and balance details are absent from several other listings, so do not infer them from the brand or stroke. A buyer rebuilding an engine with known seal and balance requirements should favor a listing that explicitly matches those requirements, then confirm the damper, flywheel, and rotating-assembly plan before ordering.
Which 400-style crank should you choose?
For a 350 build targeting a 3.750-inch stroke, begin with the Scat 4-400-3750-5700: it is the clearest listed match, with forged 4340 construction, a 350 2-piece rear seal, 5.700-inch rods, and 2.100-inch journals. Choose the Scat 4-350-3750-5700 if its forged 4340 and 3.750-inch stroke suit your plan, but verify its unspecified seal and balance details. If cast steel and explicit external-balance, 2-piece-seal details matter, consider the Eagle 104003750.
The Scat Pro Comp 9000 is a possible 3.750-inch option when a 1-piece seal is required. For a 4.000-inch stroke and 6-inch-or-longer rods, examine the Eagle 435040006000.
Confirm block and assembly compatibility before purchasing any option.
Frequently Asked Questions
What machine work and clearance checks are needed when fitting a 3.750-inch-stroke crank in a 350 block?
Mock up the rotating assembly and have a machinist check block clearance for the crank and rods, plus bearing, journal, and rod compatibility. Verify clearances through the intended rotation and confirm the assembly works with the block, oiling setup, and other components. Required machining varies by block and parts; do not assume universal fitment.
How do I determine whether my small-block Chevy needs a 1-piece or 2-piece rear-seal crank?
Identify the rear-seal design of your block and match it to the crank listing before buying. The supplied options include listings specifying a 2-piece seal and one specifying a 1-piece seal, while other listings leave seal details unclear. Confirm the block and crank configuration with your machinist rather than inferring it from stroke or material.
What flywheel, damper, and rotating-assembly balance parts must match an external-balance crank?
Use flywheel and damper components compatible with the crank’s external-balance configuration, and confirm the complete rotating assembly is balanced as intended. The listing identifies the Eagle 104003750 and one Scat Pro Comp 9000 option as external balance, but does not establish every required component. Verify the specific flywheel, damper, and balance plan with your engine builder.
How should I compare the two Scat 3.750-inch forged options?
Start with the 4-400-3750-5700 if its listed details fit your plan: forged 4340 construction, a 350 2-piece rear seal, 5.700-inch rods, and 2.100-inch rod journals. The 4-350-3750-5700 also lists forged 4340 construction and a 3.750-inch stroke, but its seal and balance details are unspecified. Confirm those details before choosing.
When should I consider a 4.000-inch-stroke crank instead of a 3.750-inch option?
Consider the listed 4.000-inch-stroke Eagle when that stroke and its stated 6-inch-or-longer rod use suit your build. It is not a direct substitute for a 3.750-inch crank; confirm block compatibility, rod choice, seal, balance, and clearances with your machinist. The supplied title identifies forged 4340 construction but does not settle fitment for every 350.
Final Words
For a 350 targeting a 3.750-inch stroke, start by checking the Scat 4-400-3750-5700 against your block and assembly; its listed seal, rod length, and journal details make the configuration especially clear. Consider the other options when their stated material, seal, balance, or stroke better matches your plan. Before purchase, confirm rear-seal design, balance components, rods, and clearances with your machinist; listings alone do not guarantee fitment.
