Mild 302 bad miss above 4500rpm
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Mild 302 bad miss above 4500rpm

  1. #1
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    Default Mild 302 bad miss above 4500rpm

    I have a mild 302 in my 65 Falcon that I pulled out of a 90 GT Mustang. It has a little port work to the stock heads, 1.7 roller rockers, edelbrock performer and a Holley Ultra HP 650DP (I have a Paxton SN-93 which I plan on adding). The ignition is a stock dist. out of an 85 Mustang, Ford Duraspark, MSD Blaster coil and new Ford 9mm wires. The exhaust consist Hedman shorty headers and 2.5 pipes. It has a 5-speed transmission and 373 gears.

    The first problem is it idles incredibly rich. The carb has four corner idle and I have all the idle screws turned out 1 turn, anything less than that and the idle starts to increase.

    The second problem is it completely falls on it's face above 4500rpm. It will pull very hard and then at 4500rpm it feels like the valves are floating. That happens in 1st, 2nd and 3rd (that's as fast as I've gone).

    Could my problems be related to the power valves? Maybe I don't have enough vacuum to keep them closed.

    What plugs should I run? What should I set the gap at?

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  3. #2
    Or Seth, either one Budweiser's Avatar
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    Have you set the float level?

    Double checked the float level?

    What's your fuel pressure look like at idle and at RPM?

  4. #3
    Senior Member Hass828's Avatar
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    Quote Originally Posted by husqy510 View Post
    I have a mild 302 in my 65 Falcon that I pulled out of a 90 GT Mustang. It has a little port work to the stock heads, 1.7 roller rockers, edelbrock performer and a Holley Ultra HP 650DP (I have a Paxton SN-93 which I plan on adding). The ignition is a stock dist. out of an 85 Mustang, Ford Duraspark, MSD Blaster coil and new Ford 9mm wires. The exhaust consist Hedman shorty headers and 2.5 pipes. It has a 5-speed transmission and 373 gears.

    The first problem is it idles incredibly rich. The carb has four corner idle and I have all the idle screws turned out 1 turn, anything less than that and the idle starts to increase.
    The second problem is it completely falls on it's face above 4500rpm. It will pull very hard and then at 4500rpm it feels like the valves are floating. That happens in 1st, 2nd and 3rd (that's as fast as I've gone).

    Could my problems be related to the power valves? Maybe I don't have enough vacuum to keep them closed.

    What plugs should I run? What should I set the gap at?
    So back the idle back down with the idle rpm screw after you lean it up some with the 4 corner idle-a/f mixture screws. You are actualy supposed to use a vac. guage and keep adjusting while targeting the highest vaccum reading
    "if we keep doing it the same way we always do..we will always get the same results"
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  6. #4
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    Float level is fine.

    Fuel pressure regulator is set at 7 lbs

    I'm going to put a vacuum gauge on it tomorrow and see what I get.

  7. #5
    Senior Member stoker2001's Avatar
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    Default check for weak or broken valve springs

    mine did that cause of broken inner springs
    you can just push on top of rocker (with valve open)with a wooden handle hammer to compare pressures..works for me
    Whacker Smacker M/E #561 IHBA "first looser"champ 2006&2007&Sportsman Driver of the Year

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