Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 

Thread: Stopped at light- foot on brake - Rough Idle?
          
   
   

Reply To Thread
Results 1 to 13 of 13
  1. #1
    kosmo101 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2006
    Location
    NY
    Posts
    21

    Stopped at light- foot on brake - Rough Idle?

     



    Have a 50 mercury with a 350 small block... manual steering/brakes. Seems when I come to a light press the pedal somewhat firm...rpms drop to idle..car starts rough idling. Pop to neutral...rpms go up a bit and all is fine. pop in drive and with foot off brake all is ok. Only seems when I am close to or holding my foot on the brake at a light in drive.

    Is this a vacuum issue since I am using the pedal to stop the car? Any help is appreciated.

    thanks kevin

  2. #2
    chevy 37's Avatar
    chevy 37 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2004
    Location
    Auburn
    Car Year, Make, Model: 1937 chevy truck& 33 fordtruck
    Posts
    3,017

    What are your specs on the engine? cam,heads, carb, etc.
    Keep smiling, it only hurts when you think it does!

  3. #3
    kosmo101 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2006
    Location
    NY
    Posts
    21

    Actually just got the car a few days ago and trying to take it all in. All manual (brakes & steering) as I am getting a workout stopping and turning the car

    I dont know the specifics off the top of my head. I do know it has mild cam in it... I just want to have educated guess or verbage before I bring it down to my mechanic.

    thanks

  4. #4
    NTFDAY's Avatar
    NTFDAY is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2003
    Location
    Springfield
    Car Year, Make, Model: '66 Mustang, 76 Corvette
    Posts
    5,370

    Are you running a PCV and if so where is hooked up?
    Last edited by NTFDAY; 08-31-2006 at 06:01 AM.
    Ken Thomas
    NoT FaDe AwaY and the music didn't die
    The simplest road is usually the last one sought
    Wild Willie & AA/FA's The greatest show in drag racing

  5. #5
    76GMC1500 is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2003
    Posts
    1,176

    The vacuum advance may be on the wrong port. It should be on a port that sees little or no manifold vacuum at idle and full manifold vacuum at part throttle.

    Otherwise, what are you idling at in gear at a light? There should be about a 200 rpm difference in idle speeds between in gear and neutral. Your idle speed may be low enough in neutral that when in gear, the motor struggles.

  6. #6
    kosmo101 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2006
    Location
    NY
    Posts
    21

    In drive idle is around 650 rpm... neutral kicks up to around 750-800 off the top of my head...

    not sure about pcv. working alot of hours so will try to get to it tomorrow.

    thanks kevin

  7. #7
    kosmo101 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2006
    Location
    NY
    Posts
    21

    problem is that when at the light...foot on brake... feels like it will stall. harder i push on pedal...rougher it gets. like is the pedal effort taking all the vacuum ?

  8. #8
    kosmo101 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2006
    Location
    NY
    Posts
    21

    dumb question but how to tell power brakes or not?

  9. #9
    tyler's Avatar
    tyler is offline CHR Member Visit my Photo Gallery
    Join Date
    Dec 2004
    Location
    gainesville
    Car Year, Make, Model: 1973 porsche 914 283 v8 '65 Galaxie 406
    Posts
    335

    this happened to me with my galaxie, i adjusted the idle air mixture and it helped, my motor wasnt getting enough fuel at idle sounds weird but it worked now the thing idles at 700 in park and 500 in gear
    Honda Motor= 1.6L
    Soda Bottle= 2L




  10. #10
    kosmo101 is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2006
    Location
    NY
    Posts
    21

    there is no brake booster... and tyler.. what kind of carb did you have.. mine has an old quadrajet.. dont know much about them.. could this be the source of my issue or may it be a vacuum issue?

    thanks

  11. #11
    Nova Dose's Avatar
    Nova Dose is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2006
    Location
    Sugar Hill
    Car Year, Make, Model: 75 Chevy nova
    Posts
    22

    Hmmm, since it could be a vacuum issue, your timing may be off a few degrees also.

  12. #12
    1JohnnyO is offline CHR Member Visit my Photo Gallery
    Join Date
    Dec 2004
    Location
    Hagaman
    Car Year, Make, Model: 71 Chevelle SS, 67 Camaro
    Posts
    404

    I was gonna mention that also....make sure that your 'tuneup' items are all correct before you go changing anything. Good plugs, wires, dist. and internals, ignition timing (important!), etc. When this is all set, and you still have a problem, then you can start to isolate it.
    When your dreams turn to dust, Vacuum!

  13. #13
    R Pope is offline CHR Member Visit my Photo Gallery
    Join Date
    Jun 2005
    Location
    Eston
    Posts
    2,270

    I'd bet that car has a booster somewhere, maybe a remote one under the floor? The symptoms you describe can only be a leaking vacuum booster.

Reply To Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink