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Can I do this to my Manifold??

Discussion in 'The Garage' started by PhoenixZorn, Apr 3, 2005.

  1. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    I've got a Holley Street Dominator Dual Plane Manifold laying around here, and I was wondering if I can use a cutter to remove the divider between the 2 planes and improve performance of it (as if it were a single plane..)

    If I would completely ruin any chance of using it, please say so... I doubt I will be doing this any time soon, just saw mention of it somewhere else, and decided to ask.
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Yes, you could do that but that will raise the operating RPM of the engine to the sacrafice of the low end RPM usage.
     
  3. 4xcrazy

    4xcrazy 3/4 ton status

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    As far as i knew, the only advantage of a "single plane" manifold, is in the upper rpm range, i personally think you'd be better off keeping it as a dual plane, these are supposed to be good for our types of motors, 1500 rpm to whatever, ,,,,something like that.




    yeah,,,what he said,,,,
     
  4. sled_dog

    sled_dog 1 ton status

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    The Edelbrock Performer RPM has a notch out of the center divider. Its probably 1" deep and 3" long. Lets the motor breath from both sides of the carb at high RPM. I'd recommend doing that to any dual plane manifold. There is more of a difference between single plane and dual plane manifolds than the plenum. Singles usually have straighter runners, so unless he recasts his intake it won't be like jumping from a dual to single plane.

    GM even did it themselves! The cast iron QJet manifold that came off my Police 350 had a hole bored through the side and through the center divider for this purpose. The hole was plugged with a fitting on the outside but left open between the divider to let the motor breath.
     
  5. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    That's what I was thinking... and my origianl post should have said "if it will eliminate the use of this manifold on a truck"....

    I do however have a 327 block that I'm rebuilding... If I put some nice stuff on it, I could still keep the manifold... I was planning to sell it for what I bought the carb/manifold combo for on e-bay, but then the mech told me how when he picked up the old intake off my 327 that it just kinda broke in half in his hands... May end up being a keeper piece... I'm gonna rebuild the Q-Jet too... though it already has a "remanufactured by Holley" sticker on it... I don't know when that was done.
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    You may have seen mention of this regarding the 6.2 diesel intake manifold. The rules don't really apply the same way to a diesel, it will only draw in as much air as it can use and often the intake can restrict that. Fact is the 6.2 will run with no intake manifold just fine...but it's pretty hard to filter the air that way :)

    I wouldn't hesitate to port match your intake though...often the cast quality leaves something to be desired. On my 6.2 intake I matched the gasket up to the intake and scribed the inside of the gasket holes. In some areas there was 1/4" of excess material, and in some areas the gasket and the port lined up. When i was done all the ports matched the dimension of the gasket holes.

    For reference I dropped the gaskets onto the heads and checked to see how bad that casting was. I was pretty happy with that part because there was very little varience between the gasket and the head ports.

    Rene
     
  7. sled_dog

    sled_dog 1 ton status

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    stock head castings always leave something to be desired, port matching isn't a big power gainer(few horse at the MOST) but I always recommend it.

    I don't see anything wrong with cutting a little out of the divider. Whole thing, no I wouldn't do that. My Burb has a throttle body spacer the same style as Turbo City(one most people seem to like) that lets the motor breath from both thottle bores.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The head side was really good actually...I was surprised. The intake I probably enlarged by 25%. How much I actually gained is debatable but I feel it has a little more snap now. At any rate is was nearly free to do...other than my time.

    Rene
     
  9. captaininsano

    captaininsano 1/2 ton status

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    Have an Edelbrock Torquer on my 455 jet boat, going from the dual plane to single was AWESOME. However the RPM did jump, and lost a little off the line, but not much. The top rpm went up too from 4800 to 5200. 5200 rpm from an Olds455 is sweet, ok a little off subject. Might want to make sure your cam will take advantage of the open plenum too...
     

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