How to find a casting number
Engine casting numbers are identifying marks manufacturers create on the block or head of an engine. These numbers are in the die cast mold and are part of each engine the mold produces. Using the casting number ensures selection of the correct parts.
BLOCK CASTING NUMBERS
Block casting numbers are not always easy to find. Sometimes grease or grime could be covering them and you might have to clean a part of the block before you can be able to see them. These numbers are also hard to read when the engine is still in the vehicule/boat. You could try using a mirror if the casting number is located in an area that is hard to see or reach.
Block casting numbers do not have any letters in them with the exception of FORD engines (ex. E4AE) and the metric model of the GM 4.3L (262 cid) which ends by 090M.
WHERE TO LOOK TO FIND THE CASTING NUMBER
For CHEVY engines, the block casting number is usually located on a ledge found at the rear of the block and has 6 to 8 digits. This ledge is located near the bellhousing. Sometimes the last three digits of the block casting number are cast into the block on the side. The most important numbers in a casting number are the last 3 digits.
For FORD engines, the block casting number is usually underneath the engine which makes it impossible to read when the engine is still in the vehicule/boat.
HEAD CASTING NUMBERS
The head casting number is located on the top of the cylinder head. The valve covers must be removed to find the number. Keep in mind that if you remove the valve covers, new gaskets may be needed.