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1979 MGB hesitation

Last post 06-17-2010, 4:35 AM by Bob Kennedy. 5 replies.
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  •  06-09-2010, 1:59 PM 23866

    1979 MGB hesitation

    I have a 1979 MGB with the original 4 cylinder engine. I bought the car restored 4 years ago. The prior owner indicated that the engine had been rebuilt the year prior (5 years ago). It had the Fireball (or whatever it was called) electric ignition modification on the original distributer. The car began hitching and hesitating and running rough and I found that the plastic sensor in the distributor came loose. I repaired it a couple of times. But the problem kept occurring. So I replaced it with a new distributor (with built in electronics, no points) and removed the Fireball. It runs better (more power on startup) but still hitched and sputtered a bit. I also replaced the ignition coil at that time. I adjusted the carburetor timeing and replaced plugs and wires. The thing still hestitates a bit on exceleration, worse after warming up. Also, after warmed up, when idling at a stoplight the engine will shake periodically while the motor seems to hitch a bit (sort of like a cough or sputter). It does this intermittently, not on a regularly timed schedule. On startup I get some black spray initially out the exhaust. Also, it is somewhat slow to start, even if it has been running awhile. I am racking my brain trying to decide what to look at next. Anyone have any idea where I should go next on this car?
  •  06-12-2010, 9:58 AM 23889 in reply to 23866

    Re: 1979 MGB hesitation

    Going through the same thing on my 77 MGB with electronic ignition and just rebuilt the  Weber carburetor so OK there.

    Need to check vacuum hoses, but with electronic fuel pump have been reading that the fuel psi might be too much for carburetor float so will try a regulator next.

  •  06-12-2010, 12:59 PM 23893 in reply to 23889

    Re: 1979 MGB hesitation

    Scratch the fuel regulator, put one on and after adjusting 1 through 6 psi, left me on the road, good thing I took a piece of copper tubing with me so as to remove the regulator and hook the fuel line back up or wouldn't have make it home.

      Britt engineering is a true challenge, there is always something to mess with.

    Scott

  •  06-12-2010, 2:26 PM 23894 in reply to 23893

    Re: 1979 MGB hesitation

      Finialy fixed the problem, it was in the timing, moved to 32 degrees of TDC (turned my electronic ignition distributor clockwise a few degrees until found proper timing by trial and error and then used a timing light to check). Should have gone to University motors to begin with on the net. Check this site out: http://www.universitymotorsltd.com/qa.php. He has a great video on how to statically check your timing and set it if you have a points distributor.

     Like John says: most carburetor problems are caused by bad timing.

    Let me how you come out.

  •  06-15-2010, 6:13 PM 23917 in reply to 23894

    Re: 1979 MGB hesitation

    I will try that and let you know how it works. Thanks for the input!
  •  06-17-2010, 4:35 AM 23930 in reply to 23894

    Re: 1979 MGB hesitation

    I just saw your post and was intrigued by the large advance your engine likes to see. I have a similar requirement. What RPM was your advance measurement made? Any chance your engine was rebuilt with nonstandard camshaft?
    BobK