Decoding a Corvette’s V8 Casting Numbers and Engine Stamps


Back in September I wrote about how documentation was the must-have option when buying a classic Corvette. That article focused on mostly the paper trail: dealer invoices, build sheets and tank stickers. Today the focus is on the engine and the clues available for verifying authenticity. While the term “Matching Numbers” in its simplist form is various serial numbers and codes located on key parts and their relationship to a particular year of Corvette, it’s the engine block that is the most important part of the matching numbers equation. Unfortunately, as Corvette values rise, so do your chances of buying a Corvette with altered numbers being passed off as an original. As my favorite mantra goes when purchasing a Corvette, knowledge is power, and the more you can learn about documenting a Corvette prior to purchase, the less likely you will get burned with buying a Corvette of questionable lineage.

A series of codes and stamps are located on the engine block that will allow you to identify it as being manufactured specifically for a Corvette. There are dates of manufacture and the engine’s original application if you just know where to look. As the year’s progressed and engine options increased, the numbering and casting system obviously changed and became more specific. For the examples provided, I will be referring to the 327 ci 300 hp small block V8 in my 1966 Corvette.

Chevrolet Smallblock V8 Casting number and engine stamping locations 1966 Corvette 327 ci V8 Engine Casting Number 1966 Corvette 327 ci V8 Engine Stamp

Casting Numbers
The casting number is a sequence consisting of raised numbers that was cast into the engine block when it was made. What’s a bit tricky here is that casting numbers on Corvette blocks can also be found on other engine blocks made by GM. Casting Numbers are important to the engine documentation process because certain numbers were used for Corvettes and some were not. Also, the numbers are specific to the size of engine in the Corvette. 283’s, 327’s and 427’s all had their own casting numbers specific to individual years, so for the process of documenting a Corvette engine, the casting number will be used to confirm that that block was used in a Corvette and that it was available during the same year the Corvette was manufactured, and finally, it was unique to a specific engine size. The casting number on Chevy V8’s is located on the drivers side of the engine where the block is connected to the bellhousing. It can be a bit hard to see with the ignition shielding in place but the numbers are fairly large. The casting number on my 1966 is 3858174 which is identified as a 327 ci V8 block. That block casting number was also used in 1964-67 passenger cars including the Chevelle and Camaro as well as Chevrolet trucks.

Casting Dates
The cast date symbolizes the date of manufacture of the block. Dates are coded beginning with a letter representing the month. Letters began with “A” for January through “L” for December. The next section of digits represents the day of the month and is either 1 or 2 digits in length. The final single digit represents the year. Corvette casting dates only show the single digit for the year. If the block contains two digits for the year, then it was a block manufactured at the Tonawanda engine plant and therefore is not a Corvette block (Corvette engines were almost exclusively built in Flint, Michigan). Cast dates on small block V8’s can be found on the passenger side of flange where the block is connected to the bellhousing. I found this number difficult to locate. On 1965-67 big blocks, the cast date is located on the passenger side of the block where the starter is attached. The cast date on the block in my 1966 is “E 5 6”, which decoded stands for May 5, 1966. If you are trying to document an engine, the casting number would confirm the size of the engine and its intended recipient, and the date code would confirm that the block was used in Corvettes.

Engine Stamping
Engine stampings evolved in the early years of the Chevrolet V8 engine. In 1955-56, it was simply a continuous serial number, but one that didn’t match the serial number of the Corvette. It was then followed with F for Flint, where the Corvette engine was manufactured and then the year (F55 or F56). The final two letters indicated the original application of the engine. Application Codes usually indicated engine size, type of fuel delivery (Injection or carburetion) and transmission. As engine options grew, so did the number of application suffix codes. In 1957, the serial number was dropped and instead the stamp contained the letter F for Flint, a three to four number sequence for month and day of assembly and then the two letter engine suffix code. Beginning in 1960 the stamp included the serial number of the car it was installed in. The 327 engine in my Corvette contains the following number sequences: 6122891 F0518HE. Decoded, the first sequence is 6 for the year (66) and then the VIN sequence of 122891. The second stamp decodes F for the Flint Plant, May 18 is the engine assembly date and the HE suffix code stands for a 327 ci 300 hp with a manual transmission.

So there you have the basics of decoding engine numbers for the purpose of documentation. Please note that there are some exceptions to the information contained above. In 1965 it is said that there was a shortage of 327 blocks from the Flint plant, so Chevrolet used some engine blocks from Tonawanda. Those engines would have a T instead of F on the stamp, as well as the full year in the cast date. There are several publications that contain a breakdown of engine codes and sequences. The NCRS also provides a publication that details how engines were stamped and therefore, may help you identify restamped engines.

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  1. It’s also important to keep the build date of the chassis in mind too. In my years helping dad restore mid years it’s easy to get caught looking for long lost parts and put a part on the car that is close but not "correct." For example, having a January motor in a June car is probably not accurate.

    Also, as a hypothetical example: you might have a ’65 built in June and need an engine part to match this car. Having a piece from July would not work even though it looks accurate. I’ve often wondered how many months one could go backwards when hunting down parts but I generally feel no more than 30 days and maybe a little less or more depending on the part.

  2. CJ:

    Thanks for the comments. I have read in various books that it is acceptable for an engine block to be cast as much as 6 months in advance of the assembly. I think like you that anything over one to two months is cause for a red flag with further investigation necessary.


  3. Keith-

    Agreed. I think it’s safe to discuss a casting date that far back isn’t unheard of for such a large piece. Particularly as you get later in the build year.

  4. Hi, I have a small block motor that a friend says is a Corvette motor because it has the spark plug wire holders on the side. The casting number is 3731548 and the number on the front is F1214LA. Can you verify that this is a Corvette motor? Thank you. Brian Stewart

  5. Brian:

    I looked up the casting number and 3731548 is a 283 ci engine block used in Corvette and passenger trucks in 1957. The F would be for Flint and 1214 is December 14th. The only thing not checking out is the suffix code of LA. Can you see the engine cast date?


  6. Keith,
    I have a 30 Ford with a 327 engine. The block numbers are the same as you listed for yours (3858174). I would like to know what the standard HP is on this engine without any add ons.


  7. Is there are series of letters/numbers stamped on the engine pad? That’s what will tell us what the original application of the engine was in terms of HP, Transmission and AC.

  8. Have what I think is a 1963 Corvette Engine, #(3782870) suffix (F103S) the could be and (I)


  9. looking at a 69 corvette stingray block # back is 3858180 and on the front machined pad is TO52IEA looking for help on this engine

  10. I recently picked up a 1956 Chevy 210 4dr sedan,, Norfolk,Va area,, in storage since 1970,, it has what I think is a Corvette 1964,, 327,, 365 Hp, AC motor with a matching Muncie 4spd,, deck # 1 65265,,,, F06I9RR,, can’t get to casting no’s yet,, engine seems original,, med GM high rise aluminum intake,, with 2 1/2 rams horn manifolds,, can you confirm what I think this is,, and is there a market for a 46 year old vette motor & trans?????????/,, also 780 Holley on top of all this

  11. I’ve got a 4″ bore engine that the front stamping is T0822HV, that translates from what I could find on the net to a 327/350 corvette engine from the Tonawanda plant.

    The casting number is 3932398, and I cannot find any information on this casting number. Any help with this engine casting number is appreciated!

  12. I have a 66 427 425 HP. T stamp pad on the engine block starts with TO does thst mean the engine is no a corvette engine since it was not built in Flint?. It is the original engine.

  13. Keith, what is the build date of you 66? Is there a publication for build dates. I am thinking about selling my 66 and I know i will be asked about numbers. My block was decked when it was rebuilt and now I am working on the numbers. My casting date on the block is B246 with a casting 3858174 and the serial is 118290. How do you come up with a car build date. Someone said it was 4/10/66 but I do not know how he arrived at the date. thanks you. George

  14. i am looking to buy a used corvette motor 3856180 T04185 CAN you tell me what year any an other info

  15. Can you tell me what I have. I was told this small block came from a 79 corvette block cast # 10416379 ser# V0807ZAH with this # under it 196451436 Thanks for your help BUTCH from seattle

  16. I have come across a corvette with an engine that has the folling numbers 3834810 5T also there is in smaller size the numbers F4 64. Can you please tell me what kind of engine I am dealing with in this car.



  17. On July 10th I sent you a email regarding an engine in a 62 vette and for some reason my computer was blocking numerous incoming emails can you resent your rsponse.

  18. I have a 62 Corvette – the number on the block is 2103604 Fiii7RF – Its supposed to be the original 327/340 hp -thanks Dennis

  19. I need to know ASAP about the number on the engine in a 62 corvete which is supposed to have the original motor. In addition to the serial number of the car stamped on the pad in front of the motor, there is another number, which is FO22TRC. I think the “F” is Flint. The O22 is Jan 2nd. The RC is 250HP. But I do not know what the “T” is for . Could someone email me and let me know. Thanks

  20. I have what is said to be a corvette engine. The stamped number on the front pad is V0821ZBB. I know the first letter is for the Flint plant, and the next four are the month and day it was built, but I do not know what the suffix letters stand for. Can some one help me out? Thanks

  21. i have an engine with cast numbers 3858174 and stamping of FI20IHCH having a hard time finding exactly what i have. I think it is a 64-67 327 300 horse but not sure.

  22. I have a 55 belair with has what i was told was a 283-250hp early vette motor I’m not planning on using this motor but would like to know what it is, I will probably try and sell it .the numbers on the front of the motor are k06c9cgc

  23. Good Day; Have an older vette 327, (63-65)? #’s on front pad are 781114887; & Vi 005HF. Any way to de code, would like to know origninal VIN of car engine came from. Thanks ; Paul

  24. Hi, I have recently bought several corvettes and I was wondering if I can find out what the engine size was for the car originaly on the vin code? Being that there are thousands of 427 blocks out there? excuse me a few hundred, the chance that I may find my engine blocks at tracy corvette or one of the other big block hordeds is pretty good I would think? I would like to make the process easier by knowing what the original engine size was..Thanks

  25. I have a small block 327, told it is a corvette engine. Can you please decode for me. I got two numbers off the front pad on the passenger side. One is(F118096) and the other is(FI005SB). Please help THANX

  26. I have a 65 L76 with TI. The casting number is correct as 3782870. The casting date is G164. Motor was built 11 07 and car 12 4. Your article says that Tonawana engines use a 2 digit year code. So how do I know this is a July 16, 64 Flint casting and not a July 1, 64 Tonawana casting? Is this just a fluke? Engine stamp pad looks original and not tampered with.
    Thank you

  27. I have a 65 L76 with TI. The casting number is correct as 3782870. The casting date is G164. Motor was built 11 07 and car 12 4. Your article says that Tonawana engines use a 2 digit year code. So how do I know this is a July 16, 64 Flint casting and not a July 1, 64 Tonawana casting? Is this just a fluke? Engine stamp pad looks original and not tampered with.
    Thank you

  28. I have a 66 with stamp pad number as follows: 6119143 and a suffix code of F04050HT. It appears the engine was manufactured in Flint on April 5th. That being said the vin sequence numbers are 114816 which would indicate a Jan or Feb assembly. Can you tell me how a engine 2 to 3 months later was put in the vehicle? Is it possible a blown engine and a dealer replacement? I was told by a old time mech that it was a matching numbers car. The casting number is 385874 which indicates the correct block. Can you help me out on this one? Thanks…

  29. Cannot find anything on my engine, can you tell me what I have and where can I cross reference in the future?

    My block is stamped VMO33270.

    Thank you.

  30. I have a 327 engine block #3858174 build date k 8 5 nov. 8 1965 suffix code is f10142AP And I have spent countless hours trying to find out what this motor is out of and horse power rating I haven’t had any luck could you please help please !!!!!!!!!!!!!!!!!!!!!! Thank you so much !

  31. I recently inherited an assemble bird t bucket from my dad built in 69′. Casting numbers on the block are GM 3849852 F0340D. I’m trying to figure what car it came from but can’t find anything on the suffix letter. It also has the original power pack heads. Any takes on this?

  32. Hi can someone help me verification my engine GM 1M0617 4P04 someone changed the engine and I don’t know what kind is it.

  33. F0620U, anybody? I’ve searched and searched and can’t find the OU suffix! 3782870 is the casting number, please help me.

  34. I have a block I bought the motoer of someone number on the side of the block says 3834810 so that wld be a 283 but was told it came out of a 68 vette and it was a 327 anyway this possible?

  35. have a 69 built on 12-19-69. one of the last 700. has a 3970010 cast 350. is it a casualty of the strike. quite a bit of 70 parts in it.

  36. So block #3737739 is Corvette? The C288 would be February 28th, 1958? Is there a way to find out if the block was an original fuel injected block by the casting number’s? Thank You!

  37. I have a 1956 Corvette 265 engine completely intact down to the original carb, disti and plug wires and of course those finned valve covers. Its for sale if you know of anyone restoring a car needing an authentic unit. I can get the numbers however it was authenticated by a mid fifties collector through the casting numbers…. all match intake, heads, block.

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