Idle Problem

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    Author Topic: Idle Problem  (Read 1968 times)

    Offline cudabob496

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    Idle Problem
    « on: August 03, 2016 - 03:02:44 PM »
    Cuda doesn't seem to idle well anymore.  Lotta shaking around, and stalling.
    Once get going, everything is fine. Thought all the shaking was due to loose
    motor mount, but they look good. Only diff thing I did about a month ago was
    spray carb cleaner all over top of carb. Maybe I got some dirt in an air bleed hole?
    Wonder if I got to take the carb apart? If I rock car, can see fuel in bowl sightglasses,
    though primary seems a little low.
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000


    Offline brasil

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    Re: Idle Problem
    « Reply #1 on: August 03, 2016 - 04:18:38 PM »
    is your timing all right ?  Vacuum leak ?

    This would be my first "constructions "....  Did it happen suddenly ?

    Had a similar issue...with my Holley carb....  a small amount of laquer from the Airfilter case was falling into the carb...and so the secondarys didn´t close 100 %  so the carb leaned out extremly...  AFR 22+ !!  So I removed the carb...saw the tiny little piece of nothing at the trottle blades..removed it... DONE !!

    Greetings Juergen
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    Offline cudabob496

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    Re: Idle Problem
    « Reply #2 on: August 03, 2016 - 04:22:19 PM »
    thanks, idle is not high so I don't think vacuum leak
    AFR is in normal range
    engine timing feels ok, but haven't checked it yet.
    condition has come on slowly, but getting worse.
    Gotta feeling somethin inside carb, and will need to
    take it out and examine closely.
    I hit top of carb with carb cleaner. Hadnt done that in 6 years,
    so maybe I washed some dirt into the carb?
    Probably should have vacuumed the carb first!
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline brasil

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    Re: Idle Problem
    « Reply #3 on: August 03, 2016 - 04:35:04 PM »
    hmmm....   could be possible that you washed some dirt into the carb...but I don´t think so.
    I would check the timing....

    Greetings Juergen
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    Offline cudabob496

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    Re: Idle Problem
    « Reply #4 on: August 03, 2016 - 09:24:27 PM »
    the carb is on the table
    let the dissection begin!
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline cudabob496

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    Re: Idle Problem
    « Reply #5 on: August 04, 2016 - 12:43:31 AM »
    so far, have found a rubber cap that is cracked.
    The cap is on what looks like a vacuum port off the main
    metering block. I drew a vacuum on the cap with my brake
    bleeder vacuum hand gun. The cap leaks. Could that be giving
    me the bad idle?? I suppose so. Must be the port to hook up the
    vacuum advance.
    « Last Edit: August 04, 2016 - 01:02:37 AM by cudabob496 »
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline brasil

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    Re: Idle Problem
    « Reply #6 on: August 04, 2016 - 04:40:29 AM »
    the cap could be the reason for the bad idle... IF  your trottle blades are too wide open....  if the TB are set correctly...the Ported Manifold port should not affect the idle...so much.  BUT  check the cap that sits under the float bowl... in front of the carb... there should be two ports  ( my Street Avenger has them )  one smal port  MANIFOLD VACUUM    and the bigger one  for the PCV ..  ( by the way a faulty PCV can also destroy the idle ! )

    Greeetings JUergen
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    Offline cudabob496

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    Re: Idle Problem
    « Reply #7 on: August 04, 2016 - 01:26:11 PM »
    Replaced cap, and will try to start it back up today.
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline cudabob496

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    Re: Idle Problem
    « Reply #8 on: August 04, 2016 - 08:48:33 PM »
    Drilling holes in throttle plates


    https://www.youtube.com/watch?v=JDPwY0LbRVY
    « Last Edit: August 04, 2016 - 08:58:32 PM by cudabob496 »
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline CUDA JAS

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    Re: Idle Problem
    « Reply #9 on: August 04, 2016 - 09:27:38 PM »
    Quote from: cudabob496 on August 04, 2016 - 08:48:33 PM
    Drilling holes in throttle plates


    https://www.youtube.com/watch?v=JDPwY0LbRVY

    My opinion is that drilling holes in the throttle plates is a band aid and can mask the underlying issues.

    Jason
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    74 'cuda 360/727



    Gearhead: car nut, automotive enthusiast, one who loves hot rods, muscle cars, hot trucks, burnin' rubber and neck snapping performance. 

    Just call me a gearhead!

    Offline cudabob496

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    Re: Idle Problem
    « Reply #10 on: August 04, 2016 - 11:15:19 PM »
    Quote from: CUDA JAS on August 04, 2016 - 09:27:38 PM
    My opinion is that drilling holes in the throttle plates is a band aid and can mask the underlying issues.

    Jason

    No, it can be necessary.
    Newer carbs have a new adjustment that replaces drilling holes, to
    solve the problem.

    I did it on my 850 two years ago, and it made a big improvement
    « Last Edit: August 04, 2016 - 11:18:52 PM by cudabob496 »
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline Chryco Psycho

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    • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
    Re: Idle Problem
    « Reply #11 on: August 04, 2016 - 11:55:07 PM »
     :iagree:
     It  is not a band aid fix  you need to get more air past the T plates without uncovering the idle transfer slots
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    Challenger - You`ll wish You Hadn`t

    Offline cudabob496

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    Re: Idle Problem
    « Reply #12 on: August 05, 2016 - 03:42:09 AM »
    I think on the new carbs its called the idle-air bypass valve.

    more usefull when you have a more radical cam.

    I've got my carb back on the Cuda. Now that I've seen the above video, wish
    I had inspected how much of the transfer slots were exposed, with my present
    idle setting, before reinstalling carb..
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline CUDA JAS

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    Re: Idle Problem
    « Reply #13 on: August 05, 2016 - 03:21:01 PM »
    I have had success opening up the secondary plates a little bit as opposed to drilling holes in the primaries.  There is a screw on the under side of the carb to adjust them.

    Accomplishes the same thing, lets a little more air in and allows you to back off the primaries to cover most of the transfer slots.

     :bigsmile:

    Jason
    Logged
    74 'cuda 360/727



    Gearhead: car nut, automotive enthusiast, one who loves hot rods, muscle cars, hot trucks, burnin' rubber and neck snapping performance. 

    Just call me a gearhead!

    Offline cudabob496

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    Re: Idle Problem
    « Reply #14 on: August 05, 2016 - 03:46:08 PM »
    Quote from: CUDA JAS on August 05, 2016 - 03:21:01 PM
    I have had success opening up the secondary plates a little bit as opposed to drilling holes in the primaries.  There is a screw on the under side of the carb to adjust them.

    Accomplishes the same thing, lets a little more air in and allows you to back off the primaries to cover most of the transfer slots.

     :bigsmile:

    Jason

    yep, something to try first
    Logged
    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000
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