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Should I get a big block engine?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazer79, Aug 24, 2000.

  1. Blazer79

    Blazer79 1/2 ton status

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    OK, I've been offered a running (but tired) 400 big block engine. The guy wants $400 for it. It's from one of those big 80s Chevrolet station wagons.

    My question is, can this block be bored to something larger, like a 454? Will I need any adapter to use my TH350 tranny?

    Thanks for your help.

    <font color=blue>//////
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  2. TheBlazerKid

    TheBlazerKid 1/2 ton status

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    YES you should get a bigblock.......but not THAT bigblock...if you want 454 get a 454, i dotn knwo exactly but you could bore a 400 probly to about 420. but like my signature says there is no replacement for cubic inches!

    Theres No Replacement for Cubic Inches!
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Actually the 400 is still a <font color=red>small block</font color=red>. The cylinder walls are siamesed (no coolant passage between cylinders) allowing for the larger bore. It also has a longer stroke than the 350.

    [​IMG]
     
  4. laketex

    laketex 3/4 ton status

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    400 is a smallblock as stated above. But the 396 is a big block. You sure that's not what you're looking at? The 400 smallblocks have serious heat issues and are prone to cracking heads. Yet Tex on ORC swears by his...ask any engine person his opinion and they're all different. Now the 400 Ford is a Midblock, they say...bigger than a smallblock and smaller than a bigblock. But you put a Ford engine into a Chev, we're all gonna hafta stand in line to slap ya around [​IMG]

    Bryan

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    Durant, Ok
    '79 Blazer in progress
     
  5. Bigmeats

    Bigmeats 1/2 ton status

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    ARGHHHH ARGHHHHH ARGHHHHH, MORE POWER, YA, YA, YAAAA,

    Carl....75 Blazer...Manhattan IL
     
  6. BlazerGuy

    BlazerGuy 3/4 ton status

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    Maybe it's a 402, which is a big block.

    [​IMG] Sept 1
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I seriously doubt they ever put a 396 in one of those 80's station wagons. However the 400 small block was used up to about 77 or so. I'm not exactly sure when they stopped using them. The 400 can also be built to be a very reliable bruiser (torque wise) and for the most part their bad rep is undeserved. The 400 also only came with 2 bolt mains.
    They were also externally balanced so if you got the 400 you would have to get the harmonic balancer and flywheel/flexplate that originally came with it.

    Personally I would probably just build a 383 out of a 4 bolt main 350. Or find the real deal (396,402,427,454,502)

    [​IMG]
     
  8. coopertwpk

    coopertwpk 1/2 ton status

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    79 was the last yr for the 400 sb, everything larger than a 350 during the 80's is a big block the 396 is called a 400 sold in work trucks as was the 402 .
     
  9. '73 K5

    '73 K5 1/2 ton status

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    Here is the easiest way in the world to tell a SBC from a BBC. Look at the headers or exhaust manifolds. Small blocks will have 2 pipes really close together in the middle and 2 on each side. The big block engines have the header pipes at equal distances from one another.

    '73 K5
    Chevy good...Ford bad
     
  10. ggallin13

    ggallin13 1/2 ton status

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  11. I thought they quite making the 396 in the early 70's and the 402 in the late 70's.The only big block I've sean in an 80's truck was a 454(from the factory).Chevy stoped putting
    big blocks in cars in the mid 70's.But hey I could be wrong.
    Good luck

    IF IT AINT BIG IT AINT BAD!!!!!!
     
  12. talldogg

    talldogg 1/2 ton status

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    First of all, the there's no such thing as a "big block" 400. The term "big block" refers to the PHYSICAL size of the block, not DISPLACEMENT. The smallest big block ever made was a 366 truck engine (I know, I own one), that doesn't sound big, but it's a BIG BLOCK. Chevy did make a 402 BIG BLOCK, but I've never heard of it being in an 80's station wagon. They did however use it in 70's passenger vehicles (including wagons).
    Second, Chevy DID make a 400 SMALL BLOCK (smaller block) and was also used in 70's vehicles not 80's.
    So a couple things, it sounds like you got the year wrong, and it's either a 400 SMALL BLOCK or a 402 BIG BLOCK (which by the was was also known as a 400, go figure).
    Regardless, either engine will bolt right up your TH350, but if it is a big block, I'd recommend going to a TH400 which will take the abuse. The price sounds right, either engine around hear would be a steal at $400. One of the easiest ways to tell what block it is, is by counting the number of bolts on the valve covers. If each cover has 4 bolts, it's a small block, if it has 7 it's a big block, good luck.
     
  13. 87Blzr

    87Blzr 1/2 ton status

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    The information is getting more and more correct. The 400 SB was used from 70-80. Certain castings from 70-72 were four bolt mains, but not all. The 396 BB turned into a 402 in 70 but GM kept the insignia as 396 anyway. Only the 454 survived through the mid seventies and they were only in trucks. I would almost guarantee it didn't have a big block unless it was transplanted which I doubt. The 400's life ended in 80 so unless its 80 or earlier it doesn't have the 400, again unless it was transplanted. Like mentioned they are externally balanced so make sure you get everything from the harmonic balancer to the flexplate or flywheel. To tell if its a 400 on the outside look at the circumference of the harmonic balancer. Because it is externally balanced it should not be smooth all the way around. There is a part of the circumference that is cut out or milled off of the edge a bit. Hard to explain but compared to a regular one it is easy to see. Check all the way around though. Whether its a BB or SB the price is right. BB are worth much more and the SB 400 is in demand. They are great engines despite the bad rap they get for the water passages and such. Most problems occur due to overheating or real high revving. They are great for trucks due to the low rpm nature of most four wheeling and they have great low end torque. I have had one for about ten years now and it was in unknown condition when I got it. In that time it has been in use for about six of those years in a 77 Blazer, 69 Camaro 4 speed, 68 Camaro 4 speed, 78 Z/28 5 speed and temporarily in a 53 Corvette. Beat on in all those cars except the Vette and no problems, still runs great as it sits on a stand waiting for the next tour of duty.

    87 K5 Siverado, 68 SS 396 Camaro
     
  14. talldogg

    talldogg 1/2 ton status

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    87Blzr is right, the most important thing is to try the get the engine COMPLETE because of the differences in how they are balanced. FYI the 454 is also externally balance so the same applies as to the SB 400. The 454 is still in use today in the Sierra and Savanna and goes by the name Vortec 7400 (7400=7.4 liters=454 CI). It isn't the same engine though, the OG was the Mark IV and I believe the current one is known as the Gen VI or Gen V.
    About boring it, boring a 402 will NOT yield 454 CI. Depending on the condition of the cylinder walls you might not be able to get that many CI's out of the block. You could swap the crank, but remember the 454 crank has it's own unique balancer, so get the appropriate one. Companies like Crower sell stroker cranks if you can't find a 454 one. Depending on the stroke of the crank, you'll get more cubes than a bore. Example a .30 bored over 350 yields 355 cubes, but a stroked 350 with a 400 crank yields 383 cubes.
     
  15. Blazer79

    Blazer79 1/2 ton status

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    I want to thank you all who replied so quickly. This is the live example of the quality of support offered by CK5. My brother (has an 86 Camaro) was amazed at such great replies. He rarely gets such good replies within one day at his camaroz28.com or thirdgen.org forums.

    I'll check out the engine again today. I'll take note on all the details you mentioned and post them tonight.

    Thanks again!

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  16. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Hey talldog, a stroked 350 with the 400 crank would be a 377 to get a 383 you have to bore 0.060 over as well as stroke it.
    [​IMG] Just splittin' hairs dude [​IMG]

    [​IMG]
     
  17. talldogg

    talldogg 1/2 ton status

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    Ooops! But you get the point, boring doesn't produce the same amount of cubes as stroking (the block!) j/k
     
  18. nyyef

    nyyef 1/2 ton status

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    i thought a 350 w/400 crank (using the 350 rods) and a 0.030 over bore was a 383. cant be bothered to pull out a calculator.

    Knife.
    knife.coloradok5.com
     
  19. talldogg

    talldogg 1/2 ton status

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    Rusty,
    I checked out this question over the weekend, and Nyyef is right. A .30 over 350 with the 400 crank yields 383 cubes, going .60 over yields 388 cubes. I found my info in the PAW catalog, and I doubt they get there facts wrong.
     
  20. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Oops[​IMG]
    Sorry dude sometimes I type faster than I think (at least 2 words a minute[​IMG])


    [​IMG]
     

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