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1955-1964 Corvette Exhaust Manifold ID

By: Alan L. Colvin 


All early Chevrolet Corvette factory exhaust manifolds are cast iron. Since the manifolds are cast, the actual casting number and date are raised above the actual surface of the part. Most casting numbers are visible when the manifold is installed on the engine. The casting number location and casting date location will vary from year to year and sometimes manifold to manifold. Some manifolds will not carry a casting date at all. Small block manifolds do not carry a year designation. 2" outlet small block manifolds will have a casting date, while most 2 1/2" outlet manifolds do not have a casting date. There were two types of manifolds being cast for Corvette, the first from the Flint, Michigan built engines, which were cast in Saginaw, Michigan. All small block Corvettes used these manifolds. The second type was cast at the Tonawanda Engine plant and all Corvette big block engines used these manifolds. The big block manifolds will be discussed and identified in the second installment of this article.


Casting date codes follow the same pattern as engine blocks, but some do not carry a year. The following is a breakdown of the casting date month codes:


Casting Date Month Code Identification


A - January G - July
B - February H - August
C - March I - September
D - April J - October
E - May K - November
F - June L - December


The number or numbers following the month code letter represent the day of the month that the manifold was cast. Sometimes, but not always present, the last number indicates the year.


NOTE: Always remember that when looking for specific dates to keep the following in mind. Try to verify the build date of your car. After the build date of your car has been verified, the actual dates you are looking for will be dated one to three months prior to the build date of the car. This time elapse allowed for the assembly of that engine, transport to the car assembly plant and installation of that engine in your car. Another thing to consider, if you have an original untouched car, is to match the casting dates of the original parts still remaining on your car. This procedure can prove to be dangerous unless you verify that these dates still coincide with the build date.


Exhaust Manifold Casting Numbers

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