idle problems

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    Author Topic: idle problems  (Read 1307 times)

    Offline Cudaah

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    idle problems
    « on: September 30, 2009 - 04:37:22 PM »
    I have a problem that I have been trying to figure out for years.  Basically if my car is left in park it will idle @1300 and when in gear goes down to around 900 r.p.m.  Pretty harsh when u shift in gear.  Any way I can get the transition from park to in gear a bit smoother?

    My combo consists of 360/380 h.p. crate.  Holley 750 DP with four corner idle. 3200 stall - MP electronic ignition.

    I have played with my carb opening the secondarys for a better idle and my timing is 16 idle and 36 total - seems to be in by 2200-2400 or so its pretty early.  I was told the MP electronic ignitions put out too much timing too soon.  Vacuum advance is not hooked up.  And no vacuum leaks I can find. 

    Anything I am missing?

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    Offline the_engineers

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    Re: idle problems
    « Reply #1 on: September 30, 2009 - 04:53:04 PM »
    Can you get your "park" idle lower, say around 1100?  You're right, definetely too much drop with a 3200 rpm converter.
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    Brooks

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    Offline Cudaah

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    Re: idle problems
    « Reply #2 on: September 30, 2009 - 05:44:07 PM »
    I sure can in park @1100 in gear will be about 750 and runs very rough.  SHould I try and tune the carb more at a lower r.p.m.?
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    Offline Cudaah

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    Re: idle problems
    « Reply #3 on: September 30, 2009 - 06:09:00 PM »
    I forgot to mention I do have a squarebore to spreadbore carb. adapter also.
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    Offline MEK-Dangerfield

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    Re: idle problems
    « Reply #4 on: September 30, 2009 - 06:39:22 PM »
    You should be able to get it to idle around 800 RPM or so in park. I assume you have a big cam, so it will idle a bit rough. As long as it doesn't stall when you shift into gear, I don't think you have a problem. Just the idle speed is set too high.

      Mike
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    Mike

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    Offline dodj

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    Re: idle problems
    « Reply #5 on: September 30, 2009 - 08:25:20 PM »
    Quote from: MEK-Dangerfield on September 30, 2009 - 06:39:22 PM
    You should be able to get it to idle around 800 RPM or so in park. I assume you have a big cam, so it will idle a bit rough. As long as it doesn't stall when you shift into gear, I don't think you have a problem. Just the idle speed is set too high.

      Mike
    :iagree: Gotta get that idle RPM down. Your secondaries should not come into play at idle.
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    Scott
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    Offline Cudaah

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    Re: idle problems
    « Reply #6 on: September 30, 2009 - 09:57:34 PM »
    I have the 4-corner idle screws so it opens the secondaries to get more air in the idle circuit. 

    I have been using 900 r.p.m. for tuning purposes.  I am thinking I should try and go to 750 and try and sec the air/fuel screws from there.

    Thanks for all your help
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    Offline Strawdawg

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    Re: idle problems
    « Reply #7 on: October 01, 2009 - 12:03:26 AM »
    Are you, by any chance, using vacuum advance with a manifold vacuum source?
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    Offline Bullitt-

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    Re: idle problems
    « Reply #8 on: October 01, 2009 - 09:36:26 AM »
    Something I heard about from a local club member, don't know if this could be your problem, but could not get his to idle.  Ended up the distributor's mechanical advance springs were to light, changing one to a heavier spring solved the issue.
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    Offline Cudaah

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    Re: idle problems
    « Reply #9 on: October 01, 2009 - 09:56:44 AM »
    I actaully have the vacuum advance disconnected. 

    I will check the mechanical advance also.

    I am also going to double check my idle vacuum and compare it to the 6.5 power valve thats in there.  I might need a smaller power valve.

    Thanks again everyone
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    Offline Strawdawg

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    Re: idle problems
    « Reply #10 on: October 01, 2009 - 10:17:37 AM »
    Quote from: Cudaah on October 01, 2009 - 09:56:44 AM
    I actaully have the vacuum advance disconnected. 

    I will check the mechanical advance also.

    I am also going to double check my idle vacuum and compare it to the 6.5 power valve thats in there.  I might need a smaller power valve.

    Thanks again everyone

    Sorry, you clearly stated that it was not connected in your first post.  I must have stopped too soon :)

    With regard to the power valve,  what is the vacuum in Park...as well as in Drive?  Also as mentioned, would not hurt to check the timing from 900 to 1300 rpm while in Park and see how much change there is.

    I assume you can put your foot on the brake and demonstrate the converter is as loose as the advertised stall.  I am sure after this period of time you know it is not tight at such low rpm. :)

    It seems something is changing whether fueling, or timing when you drop it into gear.
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    Offline Cudaah

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    Re: idle problems
    « Reply #11 on: October 03, 2009 - 04:15:21 PM »
    OK I checked everything over today.  But the car seems to idle much better today 1000 in park 800 in gear but seems like its loading up in gear.  Here are my findings

    Timing:
    20 @ 800 in gear
    20 @ 1000 in park
    34.5 @ 2000

    Vacuum:
    10.5 in park
    5-6 in gear

    So I am assuming I need to install a smaller power valve?  Also when I just stab the throttle the vacuum goes to 2 but immediately goes back to 10 in park.

    Any advise?  And thanks so much for all your help!
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    Offline Strawdawg

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    Re: idle problems
    « Reply #12 on: October 03, 2009 - 06:38:23 PM »
    I would try a 3.5 power valve...
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    Offline Chryco Psycho

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    Re: idle problems
    « Reply #13 on: October 05, 2009 - 01:34:11 AM »
     :iagree:
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    Offline moper

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    Re: idle problems
    « Reply #14 on: October 05, 2009 - 12:18:21 PM »
    Timing:
    20 @ 800 in gear
    20 @ 1000 in park
    34.5 @ 2000



    Drop your initial timing to 16°. Replace the springs with soemthing stiffer.. I've been using Mallory springs because there's a good assortmetn, or if you need a factory light spring (stiffer than the recurve kits' slight springs) send me your address and I'll mail you one. Then adjust teh centrifical to get 38° total. Re-set carb to get idle speed down to 800 in park, use a vacuum gage to set the mixture. It's a necessity with the 4 corner idling. I would suggest closing the secondary plate. I think that being open is part of your problem. Close the seconadry, open the primary with the idle speed screw to get 800 rpm and re-set the carb. Then see what it pulls for vacuum in gear and get the PV to be 2 numbers lower than that figure.
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