Doc's dual plane mod and port matching stky

Discussion in ''Da Nailhead' started by doc, Mar 24, 2011.

  1. Curmudgeon

    Curmudgeon Well-Known Member


    Can the dual plane mod be performed on 4 barrel manifold for a 350?
     
    Last edited: Sep 10, 2013
  2. doc

    doc Well-Known Member

    I dont see why not.....
     
  3. Curmudgeon

    Curmudgeon Well-Known Member

    Thanks Doc for the quick response. I can't wait to give it a try!
     
  4. 66GS425

    66GS425 Well-Known Member

    Hi Doc

    Can I assume similar benefits if converting to an EFI setup on a '66 425 manifold?

    Paul
     
  5. doc

    doc Well-Known Member

    Paul,,,,,As far as the intake manifold ,,, yes,,,,the restriction would be,,, and that in itself opens up some more possibilities :Brow: What type of efi ???? the individual port type or the modified carb type....if the individual port type, you could explore using a carb base for the flapper valve.... like a holley 3 barrel base or a 4500 base....to really get more air in..... and that is what we are talking about here ,,, a engine is nothing more than a glorified air compressor.... get the air in, use it, get it out.... anything you do to help that concept will make more power.... dont forget to make the air cleaner and the exhaust side more efficent.....:Smarty:

    If you are using the modified carb type efi... then you are pretty well stuck with the restriction that is in the unit....
     
  6. flh73

    flh73 Well-Known Member

    We'll I think it turned out pretty good. Thanks DOC
     

    Attached Files:

  7. doc

    doc Well-Known Member

    Yep,,,, beautifull,,,, now hit that puppy with some simple green or sand blast it and paint it up and you are set..... :Brow:
     
  8. Bigpig455

    Bigpig455 Fastest of the slow....

    Pretty clean, and he was able to stay out of the heat riser wall (which is better than I ever did!). Nice job! From experience, I think you'll like the result.

    If it's a fair weather driver, consider tapping and plugging the exhaust heat at the carb flange riser holes. It'll save your carb and keep unnecessary heat outta your fuel.

    Consider going recalibrating the carb to compensate for addl. air. If you look at old posts, it'll show that I went up a jet size on the primaries, and down a rod size on the secondaries and had good results. I recall Doc thought at the time I'd just gotten lucky, and admittedly there was no science in it. I could have probably ben fine with strictly the rod change.

    And good monrning Doc. Hope all is well!
     
  9. doc

    doc Well-Known Member

    Awww, Rhett,,,, I looked all over my place for a money tree and did not find one...... other than that , everything is Jake....:bglasses:
     
  10. Bigpig455

    Bigpig455 Fastest of the slow....

    It's generally on the other side of the fence.....good to hear all's well.
     
  11. flh73

    flh73 Well-Known Member

    Doc,

    It looks worse then it is I sprayed with WD after pressure washing. It will get blasted and painted up nice. Thanks!

    Rhett,

    I read your post and will most likely up the jets. Once I figure out what CAM to run. I'm thinking TA25 but not sure want to go that big (no real stall with dynaflow) I m rebuilding the entire drive train "63" riv, 401 in process, Dynaflow done, rear axle next.

    Thank
    Gary
     
  12. Bigpig455

    Bigpig455 Fastest of the slow....

    Good luck and keep us posted!
     
  13. doc

    doc Well-Known Member

    Gary,,, it is far better to slightly undercam it than to overcam it..... remember you are working on a engine that at the very , very max turns 5800 rpm.... it is a torque engine.... and torque is what actually moves a car.... :grin: you can have all the rpm's you want , but if torque aint there , the thing will fall on its face....:rolleyes:
     
  14. flh73

    flh73 Well-Known Member

    Thanks for the advise Doc. I've tried to search on more suggestions but struggling. I can't find a conservative cam. TA also has 20 series but not crazy about 470 equal lift. I have a brand new stock NOS cam, these are around 431 lift with 114 separation. Should I just run a tried and true stocker?

    thanks again
    Gary
     
  15. wkillgs

    wkillgs Gold Level Contributor

    Schneider has 262-70H and 270-80H grinds that are a little bigger than stock, both with 112 degree lobe centers.
    Figure a stock cam has 208-209 degrees duration at 0.050" lift., so the 262-70H cam is close to original on the intake buts adds a little lift/duration to the exhaust side.
    http://schneidercams.com/buick_nailhead-hyd.aspx
     
  16. doc

    doc Well-Known Member

    The cam that Walt is suggesting, sounds really good.... of course my favorite is the old original 091 that aint available any more,,, unless you have one custom ground or get really, really lucky and find one like John did....but, I would take a second look at the Schneider cam.....
    When I say ''overcam'' ,,, I am talking about taking a all out dragster cam and putting it in a street driver that has 2:91 gears in it.... that sort of thing....:laugh::laugh:
     
  17. chefcg1

    chefcg1 New Member

    I'm getting ready to do the dual plane mod, but I have a few questions before I start. Should I port match the intake runners if I'm not going to port match the head's ( I don't want to pull the heads to do that)? Should I cut down the center section or leave intact? Thanks!
     
  18. doc

    doc Well-Known Member

    No doubt you are hesitant about doing the heads because you are worried about the chips falling down into the ports...
    simple solution to that problem.... just fill the intake ports with arisole shaving cream, use the stock intake gaskets for a template,, put the ridges up,,, mark the inside diameter,,, do the cutting and then suck the shaveing cream and chips out with a shop vac... works like a charm.... :laugh: and no,,no need to pull the heads.... do both the heads and the intake manifold ports,, you will be glad you did, later....:Brow:

    leave the center divider in... do not cut it down any.... I set mine up for a holley 3 barrel carb and had to raise the carb up 3/8ths of a inch to clear the back barrel plate... and so made the adapter/heatshield just like the bottom plate of the carb...

    make any spacer under the carb just like the bottom plate of the carb... and ,,, leave the crossover heat passages alone ,, in fact make sure they are open and working,, you need the heat to vaporize the cat pee gas into a burnable vapor....

    Make your air cleaner to handle the increased air intake....
     
  19. chefcg1

    chefcg1 New Member

    Thanks Doc! Love the shaving cream idea!
     
  20. chefcg1

    chefcg1 New Member

    You mentioned a carb spacer, I'm using an Edelbrock e-1400 600cfm carb so should I go with a square bore opening or a 4 hole opening?
     

Share This Page