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Discontinued Magnum R/T Head Wanted #P5007140 vs Replacement P5155469

Discussion in 'Performance' started by mr5racing, Aug 15, 2015.

  1. mr5racing

    mr5racing New Member

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    We are trying to run an asphalt modified against a field of chevy spec motors with Dart Iron Eagle 200's. We have a lightweight bottom end vs the heavy chevys. My question is our rules only allow the Magnum R/T 7140 head that I cannot find anywhere. Mopar Performance came out with its replacement the P5155469. The problem is we are allowed 180cc head no modifications and the new head is 172cc. the old head was flowed at Shady Dell at 245@ 28in of water. Has anyone flowed these newer performance heads 5469? if im going to petition the tech inspectors to allow me to run the newer head we may have to change pistons to get to the rule 10:1 or cut the heads and manifold to fit. I know im looking for a needle in a haystack looking for the old R/T heads but Im looking. Anyone have any Magnum R/T heads as cast condition for sale if I cant petition them to allow another head?
     
  2. MoparDanno

    Level III Supporter

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    I have 3 sets of ported RT heads, including a set done by Shady, but I don't currently have any as cast R/T heads around.

    Can you use W2's? Or are you setup specifically as a magnum top end? What block are you using?
     
  3. mr5racing

    mr5racing New Member

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    The only head approved at our track in the P5007140 untouched unless its seats. I found one 7140 with 2.02s and Shady was going to put seats in it for me and restore it to factory flow but the guy grounded the R/T logo and part no. off the head. I just couldn't take a chance on it. Ive been looking everywhere and also found another brand new but I don't have a pair yet. I also don't want to ask the inspectors to make an allowance for another head to be approved when there are no other Mopar motors in the field. We built an LA block 360 with ultralight bottom end, Hughes custom cam. Also limited to the M-1 dual plane Intake. Im not sure this engine will be competitive against Chevy Dart Iron Eagle 200s, and Edelbrock Performer Intake. we do have a stroke advantage and a slight C.U. advantage but are down 1 point of compression, less flow over .500 lift and intake may be less as well. I have to take a chance and see what the results are on the dyno
     
  4. MoparDanno

    Level III Supporter

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    My recommendation would be to go for the Edelbrock performer Air-gap if you can, but if you need to stay with the M1 dual plane, notch the divider between the plenums on a mill and make it look like it came that way. Technically its not legal, but since you are the only Mopar they wont know as long as you don't make it TOO obvious and do it cleanly. That will open up your upper mid and top end powerband quite a bit with that intake.
     
  5. MoparDanno

    Level III Supporter

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    Example of a notch in a LD340

    [​IMG]

    You can make it deeper and wider by a bit, and that will help the powerband quite a bit.

    Ive been in the same boat as you, only Mopar in a field of Chevs, with limits on heads ( we were using X heads at the time, the R/T heads are WAY superior ) and we were easily out pulling the Chevs out of the corners. It really pissed off some of the higher dollar guys too, as they all knew it was our own build on the motor. Not some high dollar Gaerte or something.
     
  6. MoparDanno

    Level III Supporter

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    Oh, and do whatever you can to get that piston at zero deck. Closing the quench up is key to making power on a combo like that. FWIW.
     
  7. hemirunner426

    Level 2 Supporter

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    Year one lists them,not sure if they actually have them .I am doing some checking with automotive rebuilders here in Ontario.,will let you know if I come across any.
     
  8. mr5racing

    mr5racing New Member

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    Yeah I spoke to yearone they don't have them even though they are listed. MP just doesn't make them anymore so unless one is sitting under a bench somewhere chances are they are MIA. thanks though.
     

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