Doc's dual plane mod and port matching stky

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

  1. doc

    doc Well-Known Member

    First, you gotta get your hands on a good intake manifold,,, this one is like me,,, old and weathered...:laugh:

    and on this one I am going to portmatch it to the heads and grind off all the knuckle skinning casting flash on the outside.... you start by placing an old intake manifold gasket on the manifold with the ridges facing up toward the manifold,,, because the gasket is directional and has to be in the right location. :Smarty:

    I anchor the gasket in place with bolts in each end and then mark the inside edges with a marker...

    This is how it looks when the gasket is removed....

    then with a die grinder or drill motor and a carbide burr or stones proceed to grind over to the line in the runners...

    Now on to the Doc dual plane mod,,,first I put the manifold in the sand blasting box and cleaned it up,,,then I take a straight edge and mark the cuts with a marker...

    and then I make the first basic cuts with a die grinder and a 1/4'' abraisive cut off wheel... when you get down as deep into the manifold as possible, then switch over to a sawsall and a short blade with 14 teeth per inch because the coarser teeth cut faster in cast iron... and as you are cutting , lube the blade with tap majic or atf to keep it cool and speed cutting...:Smarty:

    after the partitions are removed then go to a 6 in. carbide burr to smooth up the sides, down into the manifold,,, this takes the most time,,, lube the burr with atf often to keep it cool and speed cutting,,, I cut my pressure back to about 40 psi... and put a fan on my compressor to keep it cool....

    after the sides are smoothed up, completely clean the manifold inside and out to get all the crud out of it and then paint it....
    Behold, the Doc dual plane.....

    Now if John , or one of you guys will stickey this thing ,,,, I will greatly appreciate it.....:Brow: :laugh:

    Attached Files:

    flh73 and 300sbb_overkill like this.
  2. gsgtx

    gsgtx Silver Level contributor

    my girlfriend walked by when i was looking at the thread, wants to know who the handsome gentleman in the photo is.
  3. 66gsconv

    66gsconv nailhead apprentice

    LOL, I gotta tell ya Doc it looks good:gp:
  4. doc

    doc Well-Known Member

    Yeah, Bob , it is amazing what you can do by whining and get other people to help....:laugh:
    300sbb_overkill likes this.

    JESUPERCAT No Slow Boat

    Doc you have been stuck:laugh: .
  6. doc

    doc Well-Known Member

    Wonderfull, John,,, thanks a bunch , pard.....:Brow:
    300sbb_overkill likes this.
  7. Bigpig455

    Bigpig455 Fastest of the slow....

    The whole process is well worth the time, I can attest. Took two tenths of my ET with no other changes. With the increased airflow, going richer with .086 jets and .048 rods were worth a tenth each too (at least in cooler weather)..not bad for a day's work.
  8. DaWildcat

    DaWildcat Platinum Level Contributor

    Excellent "How To".

    My wife made a similar comment to the one above about the nice fellow in the first pic. The pictures are worth a thousand words each.

    Doc, what happens if the center divider is lowered for higher hp builds too? Anyone tried it?

  9. v8regalowner

    v8regalowner Silver level contributor

    thanks doc, doesnt look that hard at all now. the pictures help a ton. im glad i picked up a cheap but very very clean extra intake to try first just in case a screw it up.

    JESUPERCAT No Slow Boat

    Doc's dual quad dual plane mod :Do No: so can it be done with benefits?
    No one would know and you could still have dual quads.
  11. rwg65

    rwg65 Well-Known Member

    I'm with John, Doc. Same benefits with a 2x4 manifold. Don't have an extra to try. Might be interesting.
  12. doc

    doc Well-Known Member

    Actually as much as I would like to promote the mod for dual quad set ups, I think that the improvement would probably be less percentage wise.... but,,,, that said, if you are racing and looking for the last bit of power that a engine has... Well, eelco did it on their dual quad manifold,,, so it must be worth while....but I think that the percentage of gain may be less than for a single carb set up.... :Do No: :Do No: the velocity thru the manifold would be less than a single carb manifold.....
    300sbb_overkill likes this.
  13. RJBT

    RJBT Well-Known Member

    Nice to see your face doc !!!

    2 questions:
    • For the manifold porting... do you have to do the same thing on the head side (ie: lay gasket , mark it, grind it) ?
    • The DDP (Doc Dual Plane) procedure .. is that good for a stock 1960 401 AFB carb set up if I dont change anything else ? Will it bring me anything or is it really only for souped up setups (ie: changing jets and rods) as people seem to discuss on this board ?
  14. doc

    doc Well-Known Member

    RJ,,,, It would be best if you did the heads too... but you dont have to.... the gasket seals the joint between the two.... I have the engine apart and will do that , but just havent yet....the procedure is the same for both sides, be sure to place the intake gasket ridges facing up toward the intake manifold....

    Yes you will definitly pick up a considerable amount of power, even if you change nothing else.... that is exactly what I did on my very first one... I wanted to see if the mod itsself made a I absolutely did not change anything else.... and the car, my 64 riv, ran much stronger....same afb,same air cleaner, same engine tune up....:Brow:

    My face... that guy that looks back at me in the mirror is way too old....:Brow: :laugh: :laugh: But you guys tell the ladies that their compliments made my day.....heck my week,,, my month....

    Dev,,, I never have done that,,, I think one or two have,,, but I havent heard back from them,,,, Tom T was talking about ''rounding'' the area where the air turns to go into the runners ,up at the roof of the manifold and I did do that on this one but havent used it to see if there was any difference....couldnt hurt to do what Tom was talking about.... but I would think that taking part or all of the center divider out would raise the rpm range....
    300sbb_overkill likes this.
  15. 68riviera430

    68riviera430 BRRRRAAAAP!

    Is this only for Nailheads or good for the other BBB's?
    Last edited: Mar 25, 2011
  16. doc

    doc Well-Known Member

    Adrian, I dont see why it would not work on a BBB,,, just be carefull of where you are cutting... I have not done one for a BBB,,,, and I dont think that the metal that the manifold is made of will make any difference....
    300sbb_overkill likes this.
  17. 68riviera430

    68riviera430 BRRRRAAAAP!

    Sweet, great sticky Doc, I cant wait to see the difference it makes on my Electra
  18. Silver Bullet

    Silver Bullet Well-Known Member


    I thought you favored the spreadbore intakes?
  19. doc

    doc Well-Known Member

    Actually no,,, Doug, I favor the sq. bore type because my favorite carb is the old holley 3 barrels that were made in 1968 and 69 for nascar.... and that dictates a sq. bore configuration... which I modify to the DDP....and then I have to use a adapter to make the holley fit any way, so I make it like the base plate of the carb so the 3 brl. will work right , and it doubles as a heat shield too....but dont tell Tom,,, he gets all worked up over that.....:laugh: :laugh:
    300sbb_overkill likes this.
  20. TAANK

    TAANK Well-Known Member

    I prefer the Holley carb as well just a 4150 is the only difference. Now drill and tap nitrous bosses in each individual runner and we're in business.

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