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  • curb idle too fast

    Howdy All,

    Just got my 392 running. The guy I bought it from installed a Holley 4160 (600 cfm) carb.

    PROBLEM: The engine won't run slower than 1000 RPM.

    I rebuilt the carb (just in case - although it was only 2 yrs old)

    The main jets were 65's (stock was 69 - so some mod was made) and the power valve is a 65.

    I took the metering block from the old carb (It is a 4160, but the idle circuit is smaller, to match the lower CFM) and put in the 65 main jets and 65 power valve. My thinking was that the smaller idle circuit would slow the RPM's a bit, but this did not work.

    settings:

    curb idle screws, when turned in all the way, RPM increases and vacuume rises to about 15 "Hg. Reset to 1 1/2 turns. Vacuume now at about 12.

    Fast idle screw on carb set to lowest possible on electric choke.

    Secondaries are closed when throttle is at zero (adjusted per Holley specs, secondary screw clockwise until contact, then + 1/4 turn)

    Spark plugs: New platinum, gapped at .035" (lots of carbon buildup just from running it today)

    Pertronix ignitor and flamethrower coil. Ignitor gap set at .020"

    So, here are some other mods to the engine.... I took the main pully and water pump pulley's from the 304 I took out and put them on the 392. When the timing on the 392 is set to 0 degrees BTDC (using the 304 pulley) I am at about 975 RPM, and if I go to 5 degrees ATDC, the engine lopes around 750 RPM. Vaccuume drops to about 7"Hg.

    Is the pulley mark on the 304 at a different location then the 392????? If so - I have no problem except for that mark.... Hope someone can verify that one. I checked the 392 pulley on the 304, and the marks match (#8 cylindar at TDC, timing mark is at 0)

    Anyway - hope you can help,

    Bill
    Last edited by BillCummings; 11-11-2003, 01:21 AM.

  • #2
    Easy way to check the mark is to pull the plug from number 8 cylinder, disconnect coil wire and route safely. Put your finger over the hole while someone taps the key. When You here compression point a flashlight down the cylinder turn over till the piston hits top. Timing marks should be TDC.

    My vote is it's in the Holley. I have a great dislike for them. Edlebrock 1406 works great. Or I know a guy in CDA that may help you get it fuel injected?
    [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

    1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

    1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

    [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
    [B]May be all you need to know about EFI![/B]

    and I still help local JustIH members (for fun) free! :cool: [/CENTER]

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    • #3
      The fix is IN!

      It's fixed. Thanks to Aaron on the Binder Bullitin for the clue.

      Always check the linkage clearances... When the carb was mounted originally, it would not allow the secondaries to close all the way, and when I put in the heat shield/riser gaskets, the heat shield did the same thing (not enough clearance). When I took off the carb this morning, I noticed a small dent in the shield (it's made of 1/16" thick aluminum) sorta like it was hit with a BB.

      After checking the clearances off engine, BAM! Both choke & secondary linkages were not clearing the shield. Cutting out the choke linkage area fixed the whole problem. I put back the original metering block and she runs like a fine jeweled watch that likes to smoke a bit!!!! ;-)

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      • #4
        Glad all is well!
        You should have caught that Bill!
        You driving it to the meeting?
        [CENTER]1994 Buick RoadMaSSter Estate Wagon LT1/4L60E. White and Woodgrain Sleeper...PCM 16188051 With SS/V4P/Custom Tune! WOT 12.9 AFR!

        1990 Chevy Suburban Silverado 5.7L 2wd ECM 1227747 HiWay Lean Cruise 18.5 MPG and 12.5 to 1 AFR at WOT!

        1972 IH 1210 Isky Cammed Balenced 345 4 speed PCM 16197427 Project!

        [SIZE=3][B][URL="http://www.gearhead-efi.com/"]GearHead-EFI.com[/URL] EFI Conversions and Chip Tuners![/B][/SIZE]
        [B]May be all you need to know about EFI![/B]

        and I still help local JustIH members (for fun) free! :cool: [/CENTER]

        Comment


        • #5
          meeting...

          I wish. It's still in 'tub' mode. Putting on the fenders, front end and doors this week. Gotta fix the doors - still dented to heck from the rollover.

          Where and when is the next meeting? I've got orders to Phoenix. I leave in Jan, so this will probably be the last meeting I attend. But - count me in as a member, those newsletters are great!

          See ya,

          Bill

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