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BBC conversion

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by RustBuket, Aug 1, 2003.

  1. RustBuket

    RustBuket 1/2 ton status

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    Well, I'm going to be buying a K5 as soon as I can come up with another $400 so I was just dreaming: what is involved in swapping in a BBC. Is it bolt in or do you need mounts? What about tranny: do the bellhousing bolts line up like a SBC? Just curious.
     
  2. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

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    Everything should line up. I have heard something about valve cover and Brake booster clearance issues but that is all I have heard.
     
  3. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Yea, the brake booster interferes with TALL vavle covers, and the passenger side of the firewall (IIRC) also interferes with TALL valve covers. Just stick with the boring stamped steel covers and its pretty darn close to bolt up!

    Feel free to drop me a line if you need help. I've done this swap once... and I'd be happy to help if I could.

    -Dan
     
  4. big pappa b

    big pappa b 3/4 ton status

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    I just di this conversion from a 6 cyl to 454 (thanks Dan) and had no problems at all. The tall valve covers will definitely NOT work because of the brake booster.
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Does a 3" body give you enough clearance for tall valve covers?
     
  6. big pappa b

    big pappa b 3/4 ton status

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    I think that would give you enough room for the brake booster but not sure on the firewall issue. I can look later on when I get home and make a guess but I still think it will be in the way.

    Bryan
     
  7. shaggyk5

    shaggyk5 1/2 ton status

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    just finished this swap up myself. heres the problems i ran into:

    NO problems were had with tall VC's, i have AC too. it is a close fit on both sides, but its in there with no contact on an 86 with no body lift. the valve covers are steel chromies from moroso.

    Motor mounts: i had to use small block mounts in small block clamshells. i first tried it with bb mounts in the bb clamshells, nothing lined up. then i tried the sb mounts in bb clams and it was closer, but to get all the holes alighned i needed all sb stuff.

    Crossmember: this was a big problem. when i got the motor mount situation worked out, i found that the bb fuel pump was resting ON the engine x-member, prreventing me from hooking any fuel lines up. i tried just notching it out a bit, but it was still so tight that i just ended up ripping the whole stock crossmember out and building a tubular one similar to the one on the ORD jimmy. solved all the clearance problems and will also help in the future with crossover steering clearance.

    Flywheel. I didnt bother to check that i had a dual pattern flexplate on the motor ( i didnt) so when i tried to hook up the torque converter, i found out i had to pull the damn thing back apart and get a new flywheel. I was very upset at this point. Moral: DOUBLE CHECK before you button everything up!

    good luck.
     
  8. RustBuket

    RustBuket 1/2 ton status

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    Dumb question but what is a dual pattern flexplate!? /forums/images/graemlins/1zhelp.gif

    Anyways, thanks for all the tips guys!
     
  9. RustBuket

    RustBuket 1/2 ton status

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  10. zakk

    zakk 1/2 ton status

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    i forsee a search in your future. the BBC swap has been covered extensively.
     
  11. Sparky87k5

    Sparky87k5 1/2 ton status

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    My BBC swap was a complete bolt in. I'm using the intank electric fuel pump with a Mallory 3 port fuel pressure regulator for the carb'd engine. I used all small block mounts with crossmemeber in stock location. Valve covers are GM alluminum late models. Tall valve covers would have worked but I couldn't have removed them wothout removing the brake booster. My stock ones can be removed rather easily.
     
  12. shaggyk5

    shaggyk5 1/2 ton status

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    [ QUOTE ]
    Dumb question but what is a dual pattern flexplate!? /forums/images/graemlins/1zhelp.gif



    [/ QUOTE ]

    There are basically two different torque converter bolt patterns, big vs. small, most flexplates have both patterns, but my big block came with only the bigger pattern (for the th400) and i needed the smaller (for the 700r). /forums/images/graemlins/smirk.gif
     
  13. Aquaman

    Aquaman 1/2 ton status

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    Somebody asnwer the bellhousing question, because I can't remember.

    I am thinking that Chevy uses the same trans bolt patterns on BBC and SBC. I wouldn't swear to it though.
     
  14. k20

    k20 3/4 ton status

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    yeh the trans bolt pattern is the same
     
  15. TorkDSR

    TorkDSR 1/2 ton status

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    spanky, i was reading your post thinking "damn, this kid ran into all the same problems as spanky" /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     

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