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

    i dont cut the center divider at all... because the more you cut out the more it kills the torque at the lower end....but I am not saying dont do it... just be ready for the changes that it makes....
     
  2. KDML

    KDML Well-Known Member

    Thanks Doc

    I figured that was going to be the answer. I am not interested in removing as much material as Gessler, as I don't want give up a lot of low end torque. I was just thinking a slight drop in the divider, to pick up a little mid-range. Just seeing if anyone has gone this route and what their experiences have been.
     
  3. doc

    doc Well-Known Member

    Doug,, I think that 1 or 2 have done it.... but I have not heard any feedback on the results were.... all I know is that I have real good results with mine and I dont like to fix it if it aint broke....:laugh:
    My ddp mods have all been on nailhead intakes and I have to have an adapter to put holley carbs on them anyway so I make the adapter work for the 3rd barrel in back.... the blade swings down enough that I have to have some clearance there but I make just enough for that and no more... does not affect it at all that I can tell....but by the time that happens the rpm's are up and I cant tell any difference....:Brow:

    ---------- Post added at 04:51 AM ---------- Previous post was at 04:29 AM ----------

    Neil,,, sorry, guy ,,, I did not mean to ignore your question....
    Yes, I was using the heat shield and gasket with the carter carb.... I changed absolutely nothing in the original experiment... the only change was the ddp mod... every thing else stayed the same....
    In fact,,, with my holley carbs, I still use the heat shield, but I make it up myself out of 5/16 hot rolled plate that serves as both heat shield and adapter for my holley carbs... still got the exhaust heat in the manifold... cant do without that... gotta have it to make the cat pee gas flash into a burnable vapor....I make the heat shield/adapter opening just like the intake manifold except for when I put one on a 3 barrel set up and then I have to make a clearance notch in the back so the rear plate can swing open... but that is just enough to clear and no more....
     
  4. gsgtx

    gsgtx Silver Level contributor

    000_0006.jpg
    you wont hurt low end on a nailhead with the cam your running. sorry about the other photos cound not get them off
     

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  5. KDML

    KDML Well-Known Member

    Thanks Doc

    My current plan is to use the 750 Demon carb the prior owner provided (because it is brand new in the box). I have not checked, but I expect I will need to use an adaptor as well. The prior owner had 2 adaptors in the box, one with 4 holes and one with an open center.

    Joe, assuming that is your manifold - how much did you drop the divider - it's tough to tell from that picture

    Thanks again
     
  6. CameoInvicta

    CameoInvicta Well-Known Member

    You will need an adapter to run the Demon. I'd either use the open one you have, or do the "doc dual plane" mod on the 4 hole. Running the open one would effectively accomplish the same thing as dropping the center divider.
     
  7. KDML

    KDML Well-Known Member

    Thanks Andy

    After I entered my last post, I thought to myself whether the open center adaptor, effectively does the same thing as dropping the divider. At this point, I am not going to drop the divider as I really haven't settled on the carb. The demon seems like the right choice, because it is new and free. Unfortunately, it does not fit well with my plan to keep the engine looking stock and hiding all the performance parts on the inside. If I do switch to a carb which bolts right up to the manifold, I will most likely drop the divider. I have a long way to go before I need to finalize this decision
     
  8. gsgtx

    gsgtx Silver Level contributor

    thats the one am using now,about 3/4 of a inch cut. i just tried the 4 hole spacer the other day did not like it.
     
  9. KDML

    KDML Well-Known Member

    Thanks Joe

    What didn't you like about the spacer?
     
  10. gsgtx

    gsgtx Silver Level contributor

    when i took the 4 hole off and put the open one on it help mid and upper rpm with no loss of bottom end.
     
  11. Lucy Fair

    Lucy Fair Nailheadlova

    I just installed DDModded Q-jet intake on my Riv. It's like night and day at mid and high revs. Angine changed sound :eek2:, now you can really hear those 8 cylinders.
     

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    Last edited: Oct 1, 2012
  12. snake

    snake Well-Known Member

    Lucy Fair, doing the same set up on my 425, that linkage looks like the stock set up,did you bend it to fit. My carb is a q-jet 1972 BBB 800 cfm. And I ported the intake q-jet in the same manner, what type of cam are you running.

    ---------- Post added at 06:35 AM ---------- Previous post was at 06:31 AM ----------

    Also did you have to shave any fins on that valley pan with the q- jet manifold, I have the mooneyes valley.
     
  13. Lucy Fair

    Lucy Fair Nailheadlova

    It's all stock, linkage, carb etc. So no mods were needed.
    As for the valley pan i am using this one:

    http://www.ebay.com/itm/HOT-ROD-BUI...Accessories&hash=item53ea3f3271&vxp=mtr#sp_cr

    and if you look closer you can see that i had to touch 2 fins a little bit. Curently i am running Shneider 262h cam.

    Peace Kacper. 01102012204.jpg
     
  14. snake

    snake Well-Known Member

    Ported the Q-Jet manifold then had it ceramichromed, going to use the #7042240 Q-Jet from 1972 big block buick also port matched & hogged out the exauhst manifolds then had them coated also. image.jpg image.jpg image.jpg
     
  15. doc

    doc Well-Known Member

    Wow,,,, lookin good,,,, i think that intake will flow more than a dual quad set up..... Is that powder coat stuff????
    wow.....:Brow::Brow:
     
  16. snake

    snake Well-Known Member

    Doc,
    I dont think its powder coating, its actually a engineered ceramic coating that is sprayed and baked on high heat,also reduces heat and looks like polished aluminum. The exhaust manifolds were coated with the same stuff and a thermal barrier was sprayed in the inside of the manifolds. Supposed to run cooler and the finish will stand up to alot of heat without discoloring. $80 for the intake and $180 for the exhaust manifolds. Plus it look real purdy! I noticed this company sprays alot of headers for various companys ie. eddlebrock, thats what I could see.:cool:
     
  17. william.ali.kay

    william.ali.kay Needs more cowbell!

    Damn that looks good.
    Please report back about performance and post more pictures after the install.:TU:
     
  18. custum65GS

    custum65GS Well-Known Member

    That does look sharp!!!
    There was a guy in my area advertising doing that ceramic coating for turbos and manifolds on class 8 trucks,,,he claimed 6% increase in mpg,,,but wanted $1600 to do it,,,,sounds like your guy is far more reasonable with his prices!!
     
  19. 66gsconv

    66gsconv nailhead apprentice

    Snake, That does look good. I predict :3gears: You are gonna have way more mid and top end.
     
  20. snake

    snake Well-Known Member

    Hope to have better mid and top, I'm building a cruiser 425 .30 overbore , Isky RV cam 270 int & ext dur 469 lift adv @50 214 with 114 lobe, also going with 3.23 rear posi ST400 with ST300 converter.maybe for fuel economy I might go with the 3.08 gears, will that make a diff.
     

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