Results 1 to 6 of 6

Thread: mga start and backfire

Discussions of MG Sports Cars

  1. #1
    Freshman Member
    Join Date
    Jul 2006
    Location
    new york, usa
    Posts
    8
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    mga start and backfire

    have a 1958 mga and starting has become a problem. Takes a long time to get running and before the engine kicks in it backfires in the tail pipe section. Does this mean my fuel mixture is too lean or too rich? If so what's the best and easiest way to adjust?

    Thanks

  2. #2
    Freshman Member AndyH's Avatar
    Join Date
    Sep 2007
    Location
    San Francisco, California, USA
    Posts
    24
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: mga start and backfire

    Backfiring is often caused by a lean mixture. After it's warmed up, try driving with the choke out. Does it still backfire? If not, your mixture's too lean.

  3. #3
    Great Pumpkin jlaird's Avatar
    Join Date
    Nov 2005
    Location
    Niceville FL
    Posts
    19,536
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: mga start and backfire

    Hmm, now I would have thought the other way around. Backfire caused by too much fuel in the pipe.
    Jack Laird
    Retired USAF

    Miss Agatha. On the road again and smiling at her new Calif. home.
    Fourteen shows, Eleven firsts and counting we hope.

  4. #4
    Yoda Steve_S's Avatar
    Join Date
    Jun 2004
    Location
    Southern California
    Posts
    8,335
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: mga start and backfire

    Check the mixture and timing.

  5. #5
    Freshman Member AndyH's Avatar
    Join Date
    Sep 2007
    Location
    San Francisco, California, USA
    Posts
    24
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Re: mga start and backfire

    Actually it can be either rich or lean. With a lean burn, the mixture doesn't get fully combusted in the cyclinder and unburnt fuel enters the exhaust where it ignites. With a rich mixture, the fuel runs out of oxygen and gets passed out. I believe the lean fuel issue is more common on older, carbureted cars. The choke test will tell them apart, if it gets worse you have a rich mixture. Yes and the timing could be off too.

  6. #6
    Yoda dklawson's Avatar
    Join Date
    Mar 2005
    Location
    Durham, North Carolina, USA
    Posts
    6,197
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    49
    Thanked in
    46 Posts

    Re: mga start and backfire

    It's also common for lean conditions to cause the backfire to be out the carb(s) instead of the tailpipe.

    Always check electrical things first before adjusting the carb(s). Start with a general inspection of the ignition components... plugs, plug wires, dizzy cap and rotor, coil connection.... Once you've replaced any suspect parts dress and reset the points (preferably setting dwell, not gap), then set the ignition timing. With the engine cool, set the valves clearance. If these mechanical and electric settings don't address your problem, then it will be time to consider adjusting the carbs.
    Doug L.
    '64 Morris Mini Cooper-S 1275
    '67 Triumph GT6 Mk1

Bookmarks

Posting Permissions

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