1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Car is breaking up

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Old Jun 6, 2006 | 10:36 PM
  #1  
12a4bbl's Avatar
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From: South, GA
Car is breaking up

Ok well i got a fuel pump (holley blue) and i have it regulated at 6.5 psi right now. My setup is, 12a w/ upgraded apex seals, holley 650cfm 4barrel carb., racing beat intake and header, and bridgeported motor. The car feels alot smoother normal driving now with the fuel pump but when i punch it, it breaks up. I do not have a tach at the moment but my best guess would be its breaking up at about 5/6k rpms when it wants to make power since its bp'd. What do you guys think is the problem with it just breaking up.
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Old Jun 6, 2006 | 10:44 PM
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Does it continue to break up as the revs rise, or only in a narrow rpm range, then smooth out?
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Old Jun 6, 2006 | 10:46 PM
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fuel pressure seems high to me, try 4.5 lb, have you done the fuel filter recently, is the Holley getting air across it to cool the pump, these do not cool from the fuel.
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Old Jun 6, 2006 | 10:51 PM
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it basically feels like it hits a wall when it gets to feeling like it is about at 5k rpms
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Old Jun 6, 2006 | 10:53 PM
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it just gets up and then kind of i guess chokes or something i dont know.... its like rrrrrrrrrrrrrrrrrrrrrrrrrbrbrbrbrbbrbrbrbrbrb
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Old Jun 7, 2006 | 01:02 AM
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plug gap

Sounds like a weak spark. You could try cosing up the plug gap or new plugs.
One of the upgraded ignition strategies may take care of it.
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Old Jun 7, 2006 | 01:14 AM
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Fuel pressure is good, but is it consistant into the upper rpms? Could be fuel flow, could be the secondaries, could be ignition

If it's misfiring, ignition, which you need to upgrade for the higher rpms on the bp anyway.

If it's just bogging and falling flat on it's face, fuel flow and carb tuning.

Get a TACH!!
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Old Jun 7, 2006 | 01:37 AM
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What regulator are you using to dial the fuel pressure to 6.5? If its a dial style, it will not flow enough at high rpm.
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Old Jun 7, 2006 | 03:29 AM
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Sounds more like a case of throwing a carb on and expecting it to work.
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Old Jun 7, 2006 | 07:19 AM
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Could be bad timing. Mine made that noise and it was advanced too far.
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