What is a Casting Number and How to Find it on a Vehicle

Categories: Cylinder Head Tips

Casting numbers are incredibly important for a car owner to understand when buying and installing new parts in their engine. These raised numbers, often visible on the vehicle’s engine block, provide the series number, displacement range, and date and location of its manufacture.

This code allows the owner of the vehicle to purchase parts that are compatible with the year and make of their engine. It’s important to do the research into your car and know where to find these numbers to save trouble in the future, especially if you are planning to replace parts or do some repairs yourself.


Where to Find Casting Numbers

The casting number on your vehicle may be difficult to find, as its location can vary between vehicles. The numbers may also have grime on them, making them blend in with the rest of the block. Some of the most common locations for the numbers to be found are on the sides of the block under the exhaust manifolds, the front of the engine after removing the intake manifold, and the top of the bellhousing flange.

These can be found on the block, cylinder head, transmission case, differential housing, and other cast iron parts. Depending on the make and model of your vehicle they can be located in different areas.


How to Read Different Casting Numbers

When looking at the number after finding it on your part, you may be confused at just what you are looking at. Once you understand the key to reading it, it is easy to understand and extremely helpful. For example, If you find a number that is C 20 4 that is a casting date and can be read as follows.

Corresponds to the month by using the alphabet, so A is January, B is February, C is March, and so on. The 20 refers to the day it was made, so March 20th is what we have so far. The last number, the 4, refers to the decade and can correspond to a number of dates, such as 1934, 1944, 1954, and onward.


As an example, a Ford’s casting number for a specific part may appear as the above. Using a decoder, it’s possible to accurately determine its meaning.

  • First letter – Decade of the manufacturer (D = 70s)
  • Second number – Year of the decade (9 = 1979)
  • Third letter – Model of vehicle (E = Ford Truck)
  • Fourth letter – Engineering office responsible for the design (Z = Ford Division service parts)
  • Digits 5-9 – Part description
  • Digits 10-12 – Design change

Therefore, the casting number listed above marks a service starter inhibitor switch in its first version, created in 1979 for a Ford truck.


Call the Cylinder Head Experts

Casting numbers can be very intimidating if you do not have prior experience with working with them. Clearwater Cylinder Heads is happy to assist you with your cylinder head casting number identification and set you up with one of our amazing replacements. Feel free to contact us or call toll-free at (800) 572-1963.