1. Visual Inspection (with caveats):
* Engine Bay Casting Numbers: Look for casting numbers on the engine block itself. These numbers are usually located on the side of the block, near the bellhousing or on the top of the block. These numbers can be cross-referenced with Ford engine identification guides to determine the engine's make, model, and year. However, these can be removed or ground off if someone is trying to conceal a swap.
* Engine Dress-up Parts: While not definitive, the appearance of things like the air cleaner, valve covers, distributor, intake manifold, and carburetor can offer clues. If these parts don't match the Mustang's supposed year and model, it's a strong indication of a swap. However, these parts are easily changed.
* Engine Mounts: The engine mounts themselves might be custom-fabricated or adapted if the engine isn't the original fit. This suggests a swap.
* Wiring and Plumbing: Look at the wiring harness and fuel lines. If they appear modified or excessively routed, it could suggest a non-original engine installation.
2. Documentation:
* Original Documents: If the Mustang came with original paperwork (build sheet, maintenance records), that's the best source of information. It will specify the original engine.
* Previous Owner Information: Talking to the previous owner(s) (if possible) can reveal the history of the engine.
3. Detailed Examination:
* VIN Decoder: While the VIN won't tell you the engine, it will tell you the original model specifications, including the engine code for a factory-equipped Mustang. You can decode the VIN through various online resources or the Ford registry.
* Firewall markings: There may be engine codes or markings stamped on the firewall or other body panels near the engine bay that indicate what the original engine was. These are easily missed.
* Transmission Identification: Identify the transmission. If the transmission is not consistent with what would have been factory-installed with the Mustang's original engine, that's a strong clue of a swap.
* Measurements and Physical Characteristics: Compare the engine's dimensions and features to those of known original engines for the Mustang model.
4. Professional Help:
* Mustang Specialist: A mechanic specializing in classic Mustangs may be able to identify the engine based on their experience.
* Engine Identification Services: Several services specialize in decoding engine numbers and identifying engine types.
Important Note: A truly convincing engine swap might be extremely difficult to detect without extensive investigation. A skilled mechanic might have fabricated all necessary components to make it seem original. The lack of evidence of a swap does not guarantee it's original. Use a combination of the methods above for the most accurate result.
