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Thread: Holley 750 DP Won't Idle

  1. #1
    1992ford302 Guest

    Question Holley 750 DP Won't Idle

    I have a 750 DP and cant get it to idle correctly at all i check fuel pressure its at 6-6.5 which is good i thought maybe a vacuum leak so I bought a new spacer and gaskets it helped a little bit, but didn't make it the best still wont idle good under 2000 RPM. Someone said something about resetting my primary flange so it can get better air flow because of my cam? Any info on how to do this? or another ideas? Please and thank you!!!!

  2. #2
    Join Date
    Dec 2009


    Quote Originally Posted by 1992ford302 View Post
    Someone said something about resetting my primary flange so it can get better air flow because of my cam? Any info on how to do this?
    You must be referring to the "idle transfer slot":
    Ensure you're not exposing too much of the idle transfer slot at idle (under primary throttle blades - must remove carburetor to measure with wire). Common problem. Check your carburetor manual for correct exposure but it's usually not more than .030". If so, you'll need to open the secondary blades a little bit, in order to close the primary blades (to maintain desired idle speed).
    Holley has a good video pertaining to this: (Click "How to Adjust The Secondary Speed Screw")
    Then view the "Idle Mixture Screws" video. View all their carb tuning videos.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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