Where is the part number on a crankshaft?
Crankshaft part numbers are usually stamped on a flat, machined pad on the crank itself. The exact spot varies by brand and engine family, so you may need to inspect several areas—most commonly the front timing-gear end or the rear flywheel/end of the crank.
Understanding where to look is essential for ordering the correct replacement part, confirming compatibility with your engine, and avoiding incorrect cross-application. The number you find may be a service part number, a casting number, or a lot/lot code, so you should verify it against the manufacturer's catalog to ensure you have the right specification.
Common locations on the crankshaft
Look for stamped or cast identifiers on flat, unobstructed surfaces of the crank. The following areas are the most frequently used locations:
- Front (timing-gear end) pad: Many OEM cranks have a stamped part number on a flat pad near the timing gear or the front counterweight.
- Rear (flywheel/flexplate end) flange or pad: Some engines stamp the number on the rear face of the crank where the flywheel or flexplate mounts.
- Counterweight cheek or thrust surface: In some designs, the identifier is on the side of a counterweight or on the thrust-facing surface.
- Edge or end of the snout: Certain cranks place a number near the end of the crank snout, close to the harmonic balancer or timing gear area.
- Other identifiers: Some manufacturers include a cast-in casting number or a secondary code elsewhere on the crank; this may require cross-referencing with catalogs to determine the exact service part.
Because numbers can be small or obscured by gears, seals, or coatings, you may need to clean the surface and use good lighting to read the stamp accurately. If the surface is damaged or worn, photographing the area and consulting the OEM catalog can help confirm the correct part.
How to read and verify the number
Follow these steps to identify and confirm the correct crank part number:
- Locate the stamping pad or surface area that commonly bears identifiers on your crank.
- Clean the surface with a degreaser and wipe away grime to reveal the characters clearly.
- Record the exact alphanumeric code, including any letters, numbers, spaces, or dashes.
- Cross-reference the code with the engine manufacturer’s parts catalog, dealership database, or OEM service bulletin to confirm the correct part and application.
- If needed, confirm additional specifications (stroke, crankshaft end play, main journal diameters, counterweight style) to ensure full compatibility.
Having the number allows you to confirm proper fitment, avoid misorders, and ensure that replacement parts match the original engine design and tolerances.
Notes by engine type and practical tips
Manufacturers vary in practice. General tendencies include temperature- and model-specific placement, so always verify against your exact engine family and year. If you cannot locate a clear number after inspection, consult the vehicle’s service manual, the engine’s parts catalog, or the maker’s technical support for model-specific guidance.
Summary
In most cases, the crankshaft part number is stamped on a flat, machined pad near the front timing-end or on the rear flywheel-end of the crank. If the location isn’t obvious, inspect counterweight areas, thrust surfaces, and the snout, and use proper cleaning and lighting to read the code. Always verify the exact part number against the manufacturer’s catalog to ensure the correct fit and specifications for your engine.
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It has a longer stroke. The 350. Has just under 3 and 1/2 in stroke. The 400 has a 3 and 3/4 in stroke. And it also has a larger bore the the bore size on a 350.
Where is the serial number on a crankshaft?
The crankshaft serial number is marked on the O.D. of the propeller mounting flange.
How do I tell what crankset I have?
And the fit this is a square tapered spindle crank. In this three-piece crank after removing the bolt. We can look inside. And see it is a spline style crank 10 splines make it the ISIS drive system.
How to identify a crankshaft?
To identify a crankshaft, look for markings like casting numbers or stamped identifiers on the counterweights or journals and check if it has a casting mark or a forging pad. You can also use physical measurements, such as checking the stroke length or the width of the throws, which can be more accurate for specific engine families. For cast vs. forged material, tapping it to hear a "ring" for forged steel and a "thud" for cast iron is a common method, but check the material with a file as well, noting that modern cast steel can be very strong.
This video explains how to differentiate between a cast and a forged crankshaft: 58s2HacksGarageYouTube · Dec 4, 2022
Identifying characteristics
- Markings: Look for casting or part numbers stamped or cast into the metal on the counterweights or between the journals. For specific brands, like Eagle, there may be a logo or other identifying marks on the first counterweight.
- Cast vs. Forged:
- Visual: Cast cranks may have a raised casting mark, while forged cranks typically have a "wedged forging pad".
- Sound: Tap the crank with a hammer. Forged cranks will "ring like a bell," while cast cranks will produce a dull "thud".
- File test: A file will scratch the surface of a steel crank, while it will likely skid off a hard, cast iron crank.
- Physical dimensions:
- Stroke: Measure the stroke length, the distance the piston travels, which can help identify the engine size.
- Throw width: For specific engines like Ford flatheads, measure the width of the thick throws. A 5.5-inch measurement indicates a Ford crank, while a 6-inch measurement can indicate a Mercury crank, as shown in this YouTube video.
- Manufacturer-specific details:
- Callies: Search for a serial number, as Callies has maintained electronic records since 2000.
- Chevrolet: Look for a casting number on the counterweight or between the journals, but be aware that the casting number doesn't always tell you if it's high-performance forged steel or standard cast iron, as shown in this article from holisticpage.com.
- Pontiac: Check for specific marks like "N" for nodular cast iron, and codes like "CFD" for Central Foundry Division.
- MGB: Early 5-main MGB cranks have pear-shaped counterweights, while the later 77< cast cranks have bigger, bell-shaped counterweights, as discussed in this forum post on The MG Experience.
