Results 1 to 8 of 8

Thread: Lean running high compression engine/carburettor

  1. #1
    Club Member Club Member
    Join Date
    Jul 2008
    Location
    Greenhithe
    Posts
    1,614
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default Lean running high compression engine/carburettor

    First of all the engine is a 14nv with 13 head and Weber 32/34 dmtl.

    So I’ve been at the last stages of getting the nova mot’d but having some problems with consistent running. Basically It idles fine and accelerates fine when standing. What I’ve noticed is after a run or 2 up and down the street I’ve found the carburettor surging/bogging down on every press of the pedal.
    After speaking to a mechanic I know he thought it could be a vacuum lock between the tank and pump but the vacuum release line is new, there’s no vacuum sucking when removing the fuel cap, and the pumps pumping fuel freely.
    After checking the plugs, they are clean with White tips which tells me it’s running lean. A few other signs of it being lean are running hot (gets to temp very quickly), and a smell from the exhaust which is not fuel.
    ive fitted a larger main jet on the primary side (from 117 to 130) this has given a smoother acceleration but hasn’t seemed to improve the leanness.
    Ive not changed anything else. The engine is high compression so sucks a fair bit of air in.
    What can I do to increase the amount of fuel to run richer? Larger main again?

    any help is grateful

  2. #2
    User
    Join Date
    Jan 2004
    Location
    Ash vale, Hampshire
    Posts
    1,471
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    Take it to a carb specialist and have it set up properly on a rolling road.

  3. #3
    Supernova Club Member millworm's Avatar
    Join Date
    Sep 2012
    Location
    Sutton, Surrey
    Posts
    3,752
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    +1 for rolling road, you'll be pissing in the wind without getting proper gear on it to see what shes doing

  4. #4
    Club Member Club Member
    Join Date
    Jul 2008
    Location
    Greenhithe
    Posts
    1,614
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    This has been an obvious preferred choice but I’d hoped to make it drive somewhat further than it currently does so It would require trailering. Have looked locally but not had much luck finding somewhere.

  5. #5
    Supernova Club Member millworm's Avatar
    Join Date
    Sep 2012
    Location
    Sutton, Surrey
    Posts
    3,752
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    Bit of a bop but spoken to atspeed racing?

  6. #6
    Club Member Club Member
    Join Date
    Jul 2008
    Location
    Greenhithe
    Posts
    1,614
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    I’ve contacted 2 rolling roads within a 30min drive of mine, one doesn’t work with carbs but Track n Road in Essex does. They have quoted around £120 to set up. The only thing I need to think about is transporting the car their and back.

  7. #7
    Club Member Club Member
    Join Date
    Jul 2008
    Location
    Greenhithe
    Posts
    1,614
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    This one didn’t come up in any searches so will contact them too.

    Quote Originally Posted by millworm View Post
    Bit of a bop but spoken to atspeed racing?

  8. #8
    Senior User mowgli's Avatar
    Join Date
    Apr 2002
    Location
    somewhere in the 80's, hinckley
    Posts
    35,194
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default

    What dizzy & cam carrier are you using?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •