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TECH: Chevy Engine Numbers

Discussion in 'The Hokey Ass Message Board' started by squirrel, May 23, 2007.

  1. squirrel
    Joined: Sep 23, 2004
    Posts: 37,092


    I seem to answer a lot of questions about Chevy engine numbers, so I thought I'd share some of my "secrets" here in a tech post. Chevy was pretty good about putting a lot of information on their engines, and the numbering systems have stayed mostly the same for a long time. The mid 50s and earlier engines are stamped differently than the newer ones, but the casting date numbers work the same back into the early 1930s. Each engine will have 3 or 4 number sequences that when combined, will identify what the engine is from.

    We will start with the block casting number, which is from 6 to 9 digits long. On the straight 6 engines, it is on the back on the passenger side of the block, hidden or almost hidden by the starter motor, or along the middle bottom of the block, possibly hidden by an engine mount. On the V8 engines, it is on the top of the block, at the back, above the bellhousing area. Casting numbers for Chevy V8 engines can be found at:

    Casting numbers for Chevy 1937-1962 (stovebolt) inline six blocks can be found at:

    and for those and newer straight 6s try:

    At the same area where you find the block casting number, you will also find the casting date code. The date codes are sometimes ambiguious, because they don't have the whole year, only the last digit (with a few exceptions). The casting date code is a letter followed by 2, 3 or 4 numbers. The letter is the month, A = Jan, B = Feb, C = March, etc up to L = December. The second or second and third number is the day of the month. The last number (sometimes last two) is the year. Some examples:

    C 1 2


    C 1 62

    if it's march 1st, 1962

    or B 16 2 (for Feb 16, 1962)

    The casting date is usually a day or two or three before the engine assembly date, but sometimes it's weeks or even a month or more earlier.

    The third set of numbers is the engine number stamped into the block. It will be on a machined pad at the base of the distributor on straight sixes, or on the deck surface just in front of the passenger side head on V8s. Some newer V8s have it on a little machined pad just above the timing cover. The stamped code on 30s-mid 50s engines includes some variation of the car model code, and a sequential engine number, but no date information. An example is:


    J = 1951

    Mid 50s engine have a sequential engine number, engine plant, the last two ditits of the year, and the letter suffix code. An example is:

    123456 F56B

    F = Flint engine plant
    56 = 1956
    B = truck 265 with hydramatic

    The stamped code on 1957 and newer engines tells you the engine assembly plant, the month and day of assembly, and the type of engine and what it was used in. The code looks like this:


    The first letter tells you what plant the engine is from, either V or F (Flint, MI), it could be T (Tonawonda, NY).

    0306 is march 6th, the assembly date. Notice that the year is not given here. Before about 1960, the date does not have the leading zero, so in this example you would see F306AF.

    AF is the suffix code. It can be one or two letters on 1969 and older engines, and three letters on 1970 and newer. The first letter of the 3 letter code on early to mid 70s engines will often be C for Chevrolet car engines, and T for chevrolet truck engines. There are literally hundreds of suffix codes, and I will not attempt to list them all here. I do have some books that list many of the codes from the 50s to the 70s, in addition to the ones pictured here, if you need help finding one please send me a PM. There are also some wierd codes for replacement engines and crate engines, sometimes they include an R at the end of the suffix, or the suffix is CE for "counter engine" (or whatever else it might mean?). Trivia: the LS-7 crate 454 that Chevy sold in the 70s and 80s has the suffix code XCH.

    The last number sequence is the partial VIN, which was used beginning sometime in the 1960s. This will usually be found stamped next to the engine code. It will have 9 characters, the first three are the interesting ones, the last 6 will match the last 6 digits of the VIN that the engine was originally installed in. If you are looking at a car that claims to be "number matching", what that means is that the 6 numbers on the block match the 6 numbers on the car's VIN plate. If they don't, then it's not a number matching car! (and even if it has the correct number, it's possible it was restamped). We HAMBers usually don't give a shit about matching numbers, but at least now you know. Here's how the partial VIN breaks down:


    first number is the carline, which is 1 for Chevrolet, 2 for Pontiac, C for Chevy truck, T for GMC truck.

    Second number or letter is the year, it will be the last digit of the year on 1960s and 70s cars, and a letter starting in 1980. A = 1980, B = 1981, C = 1982, etc.

    Third letter or number is the vehicle assembly plant, in this case K for Kansas City.

    Attached Files:

  2. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 18,297

    Jalopy Joker

    Thanks-hard info to find.
  3. Deuce Roadster
    Joined: Sep 8, 2002
    Posts: 9,520

    Deuce Roadster
    Member Emeritus


    Good information for sure ... maybe this photo will help newbies find the locations that Squirrel listed ... :D
    jeffd1988 likes this.
  4. houtex63
    Joined: Jun 9, 2006
    Posts: 471

    from houston

    nice, thanks for the info
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  5. Flathead Youngin'
    Joined: Jan 10, 2005
    Posts: 3,530

    Flathead Youngin'

    man, good stuff! thanks
  6. AHotRod
    Joined: Jul 27, 2001
    Posts: 9,651


    Your a RULER !
  7. fiat128
    Joined: Jun 26, 2006
    Posts: 1,429

    from El Paso TX

    Cool tech, that's good info to have since there are so many Chevy blocks that are sitting around out of whatever they originally came in.
  8. Lucky Strike
    Joined: Aug 14, 2004
    Posts: 1,666

    Lucky Strike

    Very good info. Thank you.

    I just want to add that if the number stampped on your block begins with "CE" then it is a counter exchange engine. The 327 I'm working on now has that and it is my understanding that a counter exchange motor is one that was replaced under warranty.

    Essentially this limits the amout of information you can learn about the motor. All I know is that it is a replacment 327, and I found it in a 1967 3/4 ton chevy truck, but it has flat top pistons. I believe some trucks had dished pistons.
  9. dan34
    Joined: Sep 18, 2006
    Posts: 57

    from Norway

    Very helpful! I've been meaning to check what my engine came out of
  10. babyboomer
    Joined: Apr 3, 2008
    Posts: 6


    hey squirrel-thanks for the great info on deciphering engine numbers.I'm see where my inline 6 engine number F0803TPR breaks down to flint Aug. 03 truck but I can't find what pr stand for.Also casting number is 3994257 can't find that anywhere on the web either?Any help would be really appreciated.
    Joined: Nov 27, 2007
    Posts: 542
    from New Jersey

    Good info

    I have two 1990 chevy 350's that dont have serial numbers.

    They were built by Mercury Marine.

    Im curious do the GM crate engines have serial numbers?

  12. My 454 has an oddball number that doesn,t show up anywhere...I guess that,s because it was originally a 330 horse Crusader marine engine out of a boat! The casting number does show up as a truck block.
  13. j-jock
    Joined: May 12, 2007
    Posts: 704


    I also have a 1968 427 block with a serial number that I have never been able to place.
    The number starts with CCxxxxxx.. , which doesn't match any car that I am aware of. I was wondering if it was a replacement block ( I have never seen any with serial numbers stamped on them ), or a Mercury Marine motor. All the moving parts, manifold, and heads are 435 horse. The crank is also a puzzle, it is a cross drilled, grooved crank, and I thought Chevy had stopped grooving the cranks.
    Any help would be appreciated. I was going to put some flat top pistons in it, but have built up a 454 for my truck instead.
  14. 52 csb
    Joined: Mar 14, 2008
    Posts: 430

    52 csb

    Joined: Jan 28, 2008
    Posts: 426


    I just got 1955 chevy with the engine serial number KO613TJZ. What is it!
  16. squirrel
    Joined: Sep 23, 2004
    Posts: 37,092


    1973 chevy pickup 4bbl 350.
  17. oilslinger53
    Joined: Apr 17, 2007
    Posts: 2,410

    from covina CA

    Thanks for posting this squirrel, very helpful, as always.
    Joined: Jan 28, 2008
    Posts: 426


    Thanks for the input.
  19. ####----A Yardstick !!
  20. Ranunculous
    Joined: Nov 30, 2007
    Posts: 2,444


    Damn! My motor isn't a super deluxe hi-po 350;it's a 305 smogger?!
    Thanks for the great info!
  21. mgag303
    Joined: Aug 29, 2009
    Posts: 1

    from New York

    Hi Everyone, As you can tell I'm new to this forum.
    I came across it when researching some engine numbers for a 1962 Corvette. The car was purchased from a friend 5 years ago, and he has had it since 1972, so the last 37 years have been accounted for. Nothing was done to the car in the 37 was stored and occasionally driven (no enginge swap etc..)

    Here is my dilema: I've researched the engine numbers and cant figure out if its from this car. The rear block casting is 3782870 which show a 62-67 327. that make sense.

    Then there is the stamping on the front plate: # 102596 FO2030EC ***plus** a third set of numbers in the top left above 102596 "B 1304 62"

    The # 102596 matches the V.I.N.# but the "EC" suffix doesn't. Can anyone tell me why? And........what are the third set of numbers from? Could this be a dealer replacement?

    I have pictures if needed.

  22. squirrel
    Joined: Sep 23, 2004
    Posts: 37,092


    looks like a used 327 engine from a mid 60s Chevelle was swapped into the car, and someone thought it would be nice to stamp part of the VIN on to the engine?

    Might look for the casting date code on the back of the block, see what year it is.
    Joined: Jun 3, 2005
    Posts: 7,025


    This is possibly correct. I've also seen cases where there are indeed duplicate codes used. Usually they're completely different engines and even different years, hard to make a mistake or even a judgement call in that case. There's other possibilties as well. There could have been a hold up in production and something was pulled. The engine could have been a replacement and like stated above, VIN stamped by the dealer network. Some places actually gave a shit or had to define warranty issues. While most all of this can be taken as 100% spot on great info always remember that when it comes to the OEMs spitting cars out like a sausage press, nothing is sacred or carved in stone.

    Thanks for the post man. This is helpful to all Bowtie fans.
  24. Have a 69 3/4 PU BBC YQ suffix, 60 El Camino SBC MB, 60 Impala SBC CMJ Cant find enough info on these 3. HELP?? Thanx, Dave
  25. 21tat
    Joined: Jun 8, 2006
    Posts: 830


    That's a good one. Thanks.
  26. squirrel
    Joined: Sep 23, 2004
    Posts: 37,092


    original engine in that truck, it would be in front of a TH400, 4bbl, 9:1 compression

    could be a 67 camaro 327 2bbl manual trans with AIR (smog pump)

    74-76 350 car 145-160 hp
  27. Thanx much sir!!! HAMB comes thru again!! Dave
  28. dan1s
    Joined: Sep 16, 2009
    Posts: 3

    from New York

    Hi, I just picked up this small block to rebuild but I can't find the suffix code anywhere. I have checked all the web sites on the internet and all of the books that I have. The casting numbers on the block are 3970010. The numbers on the heads are 39271 85. But on the front pad I have V0402CLY. "What is CLY"


  29. Dave K
    Joined: Jan 31, 2006
    Posts: 344

    Dave K

    The motor number info it great. Thanks for posting it
  30. 65c10250
    Joined: Feb 26, 2012
    Posts: 2

    from Oklahoma

    Hi I'm having trouble and was wondering if u can help me?i have a 250, and trying to find out the year, casting is 473483, under it is k43 and behind distributer f1109faw if u can help my email Kevin

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