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  1. #1
    Member
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    Corvette(s)
    1969 Fathom Green 427 4 speed coupe

    Default How to tell a car was originally a big block car

    I've been looking for a big block vette for a while and have had people claim they have non numbers matching ones.
    One of my fears is that someone will try to sell me a small block vette that they have placed a big block in it. It's been my experience, when people put a big block in car that came with a small block, unless it done correctly, you tend to have a lot of problems.

    On a 68-72, if the seller of a vette does not have original paperwork.
    What are the most obvious items should an original corvette big block car have? (not including the engine of course)

    I believe I have heard that it needs to have a rear sway bar?
    I assume its either there or its not, assuming no one has placed one on the car afterwards)

    Larger radiator? Dont want an overheating problem.

    Larger diamaeter half shafts?( I read that the big block ones are 3 inch diamater?)

    Big block hood. (easy to replace but would need a paint job)

    Is the fuel line different?

    Thanks for any help,
    jim

  2. #2
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    Member 6880 Mike's Avatar
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    1968 convertible; 1980 L-82

    Default

    Among other things...
    Quote Originally Posted by entropy454 View Post
    ...I believe I have heard that it needs to have a rear sway bar?...
    Correct and the easiest thing to look for. Front sway is also a larger diameter than the small block cars. Front springs will have a higher rate; check for existing tags. Shocks, but it's likely the originals were replaced over time.

    ...Larger radiator?...
    Most big blocks had the 4 row Harrision copper/brass but there were expections. Fan shroud could be big block specific.

    ...Larger diamaeter half shafts?...
    Correct with larger yokes.

    ...Big block hood...
    Yep.

    ...Is the fuel line different?...
    Return\vent line might be absent. Red line on speedo could be higher. Fan and fan clutch could be different. Coolant overflow tank may or may not have been used depending on the application.

    As you are aware, any and all of the usual items identifying a big block car could have been added by a previous owner. The best way to ensure you're spending big block bucks for a genuine big block is documenation with the car.

    Good luck.


  3. #3
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    Member Vettehead Mikey's Avatar
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    Corvette(s)
    1973 Coupe

    Default

    Half shaft diameter was the same on both SB and BB cars. BB shafts were shot peened, SB were not. Only difference is that BB yokes had caps to retain the u-joints, SB had straps. Broadcast code on the bottom of the diff would be a clue.

    Might help if you tell us what year car you're looking at.

  4. #4
    Member 73shark's Avatar
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    Corvette(s)
    1973 Orange Metallic L-82 Coupe

    Default

    My L-82 has a 4-core radiator. LT-1s had the BBC hood also.

    The 73s and 74s had the extra valence extension to help force more air thru the radiator.

    Doesn't the VIN ID the engine? The 5th digit on mine does.

    You'll have to scroll down to your year. http://service.gm.com/dealerworld/vincards/ Unfortunately it doesn't go past '72.
    Save the wave

  5. #5
    Kelly454
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    If you could tell me what year, I could really nail it down for you.

  6. #6
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    Corvette(s)
    1969 Fathom Green 427 4 speed coupe

    Default

    Well im looking at a couple a 70 and a 72 currently. Are there a lot of differences between the 68-72 big block cars ?

  7. #7
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    Corvette(s)
    1968 Corvette Convertible

    Default

    Anyone know what the three digits right next to Chevrolet in Trim Tag signify for a 1968 Corvette Convertible?
    Chevrolet : Corvette:eBay Motors (item 150370177717 end time Sep-09-09 07:44:31 PDT)

    I posted pics of trim tag number/letters in question are E06??

    Thanks,

    Scott

  8. #8
    Member
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    Corvette(s)
    1969 Fathom Green 427 4 speed coupe

    Default

    How hard is it to add a rear sway bar on a small block car that didn't come with it from the factory? Is it a bolt on or is there any drilling/fabricating?

  9. #9
    Member navy2kcoupe's Avatar
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    Corvette(s)
    2000 Navy Blue Coupe A4 Z51

    Default

    E06 "should be" the 6th day on the 5th (E) month of production. I don't know when the production run started for the 68's, but I'm sure that someone here will chime in. Suppose that the production run for the 68's started in September of 67. That would make the "E06" indicate a production date of January 06, 1968.
    Andy
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  10. #10
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    Corvette(s)
    1976 medium blue

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    Quote Originally Posted by entropy454 View Post
    How hard is it to add a rear sway bar on a small block car that didn't come with it from the factory? Is it a bolt on or is there any drilling/fabricating?
    It is bolt on, most suppliers carry them, you might to increase the size of the front sway bar if adding a rear one.

  11. #11
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    Corvette(s)
    1968 Corvette Convertible

    Default

    Thanks Andy! Thought it may gain insight into my vette being original BB. But no such luck. I do know it has the BB options listed here in this thread. As much as I hate to do it...have to sell my baby!

  12. #12
    Administrator Evolution1980's Avatar
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    Default

    The CAC already has all the VIN and trim tag info that you may be looking for!

    1970 VIN info

    1972 VIN info

    In general, go up to the top most menu here, click on Tech -> Model Center
    Then click on the year you want to know about.

    It doesn't cost anything to EXPLORE the site!

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  13. #13
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    Member 6880 Mike's Avatar
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    Quote Originally Posted by navy2kcoupe View Post
    E06 "should be" the 6th day on the 5th (E) month of production.,,
    Correct.

    ... I don't know when the production run started for the 68's...
    August, 1967. E06 would be Wednesday, December 6, 1967.


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