BBC Head Swap question
+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 14 of 20

Thread:
BBC Head Swap question

  1. #1
    B-Town Bomber CAMDIDDY's Avatar
    Join Date
    Dec 2008
    Location
    Brawley, CA
    Posts
    62

    Default BBC Head Swap question

    So I blew out one of the water ports on one of the heads on my boat. I don't know squat about the motor other than it's a 454. Found a motor/tranny combo local for cheap. Pulled the heads off and block, pistons cylinder walls look fine. So I'm thinking about just swapping the heads and manifold.
    My question is about water circulation. The old manifold (left) appears to have water ports to flow throug the center of the manifold under the carb. There is no exhaust ports on the old manifold. The new manifold had exhaust ports. Do I need water flowing through the manifold? Or not? Any other issues or questions please feel free to help out I'm a newb to this stuff. Thanks


  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member
    Join Date
    May 2014
    Posts
    266

    Default

    No you do not need water running under the carb nor do you need to run the exhaust under the carb they did that to keep the manifold from icing up on cold days in a car now I don't know about you but when we are on the boat it's always hot out you can buy gaskets for the intake that block of the exhaust at the heads from flowing threw the manifold

    also in your pic the old manifold is for a square bore carb and your replacement. Looks to be for a spread bore carb you should check to see if your carb will work if not you'll need an adapter plate

  4. #3
    Senior Member Mojave85's Avatar
    Join Date
    Feb 2008
    Location
    Boise, Idaho
    Posts
    628

    Default

    That Performer intake manifold is set up for either a square bore carb or spread bore carb and in my opinion is the better manifold of the two. Clean it up and run it.

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    B-Town Bomber CAMDIDDY's Avatar
    Join Date
    Dec 2008
    Location
    Brawley, CA
    Posts
    62

    Default

    great thank you both

  7. #5
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default

    If you are talking about the 2 lines on top of the manifold...on either side of the carb...no clue what those or....nor have I ever seen anything like that before.
    If you are talking about the ports on the UNDER side of the manifold ...that goes under that carb. That is a hot air cross over.....block that off...you dont want or need it in a boat.
    Another Hot Boat refugee

  8. #6
    Senior Member DuaneHTP's Avatar
    Join Date
    Dec 2007
    Location
    Shell Knob, MO
    Posts
    1,379

    Default

    That's an old trick to block off the exhaust ports of the heat riser for the carburetor and run water through it to cool down the incoming charge of fuel mixture. As hooky as it looks, believe it or not it works.

  9. #7
    Senior Member
    Join Date
    May 2014
    Posts
    266

    Default

    Also just looked at your pics agin I know the edelbrok came of a truck but your old main old has a vacuum port with two big lines coming off now I could see one going to a PVC but what's the other one for kinda odd for a boat is why I ask

  10. #8
    B-Town Bomber CAMDIDDY's Avatar
    Join Date
    Dec 2008
    Location
    Brawley, CA
    Posts
    62

    Default

    so just block of the heat port on the new manifold with a gasket? and i think the one vacuum line and the other is blocked off not sure why its there.

  11. #9
    Senior Member Mash on It's Avatar
    Join Date
    Mar 2008
    Location
    Willow Beach & BHC
    Posts
    170

    Default

    Is that offy a single plane? I cant tell from the pics. if it is, I'd use it.
    Dual plane manifolds are for motorhomes and tow trucks, I prefer a single plane on a jet boat.

    That water cooling is goofy but cool at the same time, form follows function.

    Dan'l
    "Never mind the mule, Just load the wagon"
    '76 Eliminator 21'

  12. #10
    Senior Member
    Join Date
    May 2014
    Posts
    266

    Default

    Duel planes work good on stock apps and as for the blocking off the heat tubes they sell intake manifold gaskets that don't have cut out for it that blocks the flow to the manifold

  13. #11
    B-Town Bomber CAMDIDDY's Avatar
    Join Date
    Dec 2008
    Location
    Brawley, CA
    Posts
    62

    Default

    I need to get back to the shop and take another look, but I think I remember something about the old offy not matching up with the new heads.. i may be mistaken. shouldnt all this stuff be interchangeable? or do certain bbc heads and manifolds pair up with each other?

  14. #12
    Some guy obnoxious001's Avatar
    Join Date
    Dec 2007
    Posts
    3,570

    Default

    Quote Originally Posted by CAMDIDDY View Post
    I need to get back to the shop and take another look, but I think I remember something about the old offy not matching up with the new heads.. i may be mistaken. shouldnt all this stuff be interchangeable? or do certain bbc heads and manifolds pair up with each other?
    There are rectangular port heads and intakes, and oval port. We can see the Edelbrock is oval port, it says right on it. The other variation is that there are larger and smaller ovals, so it's a good idea to measure and match. An intake gasket is a convenient way to compare and check alignment based off the bolt holes.

  15. #13
    B-Town Bomber CAMDIDDY's Avatar
    Join Date
    Dec 2008
    Location
    Brawley, CA
    Posts
    62

    Default

    Yes the offy and old heads were more rectangular and the new stuff is more square. That's why I'm not sure if I can match the offy with the new heads.
    What's the downside of the dual plane manifold?

  16. #14
    Senior Member
    Join Date
    Sep 2008
    Location
    Rancho Cucamonger, CA
    Posts
    140

    Default

    Quote Originally Posted by CAMDIDDY View Post
    ..What's the downside of the dual plane manifold?
    none as long as you jet your carb properly.

+ Reply to Thread
Page 1 of 2 1 2 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in


Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95