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  •  » Mustang Bucking

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    7/26/2014 10:29 AM  #1

    wsinsle
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    From: Belle Vernon, PA
    Registered: 4/01/2013
    Posts: 1,664

    Mustang Bucking

    Took dad around the block for his first ride in the Mustang. The motor was jerking, kinda of back firing when under load. When sitting in the driveway just reving the motor itseemed fine. It's a rebuilt 289 with mechanical advance, autolite 4100 carb. The carb has 48 jets in the front and 62 in the rear, haven't really done any fine tuning on the air fuel adj.  Any thoughts on the rough running under load?



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    7/26/2014 10:48 AM  #2

    Derek
    I FYI 24-7

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    From: Eatonton GA
    Registered: 4/01/2013
    Posts: 549

    Re: Mustang Bucking

    Well as you said, you need to tune it. Get out your vacumme gauge and timing light . Then start setting the timing, air/fuel, advance on the distributor, and idle.

    Last edited by Derek (7/26/2014 10:48 AM)

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    7/26/2014 11:55 AM  #3

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 11,746

    Re: Mustang Bucking

    Put some fresh gas in it, advance the timing a little and hang on!

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    7/26/2014 8:49 PM  #4

    6sally6
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    From: Surfside Beach,SC
    Registered: 4/02/2013
    Posts: 6,466

    Re: Mustang Bucking

    X-2!
    6s6

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    7/27/2014 4:59 AM  #5

    hmartin025
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    Registered: 4/01/2013
    Posts: 365

    Re: Mustang Bucking

    Imho, from your info, its a high voltage problem probably plugs or wires. Think of it this way, with no load on the engine runs fine but driving (load) have a miss, that indicates coil, plug wires, plugs, cap & rotor.
    One or more listed will probably be the culpret.
    Howard

     

    7/27/2014 8:58 AM  #6

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Mustang Bucking

    Looking at your pictures, your first drive must have been timed exactly like the first drive of my fastback way back in early 21st century.  My car did the exact same thing and the problem went away with some fresh gas.  It would idle fine and rev just fine with no load, but would not run well when trying to move the car down the road.
    Whenever I see first drive "issues" it can certainly be affected by the fact the car may have sat in the shop for two or more years and the gas volatility is compromised.  Not to say it can't be some other issue as the great suggestions from others have detailed, but if you do not have fresh gas in it, that is about the easiest thing to fix.

    Your pic brought back some old memories.  Only mine did not have doors.  No hood, no fenders, no doors, no windows, and a 5 gallon bucket for a driver seat!
    Yours looks completed by comparison!

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    7/27/2014 9:40 AM  #7

    wsinsle
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    From: Belle Vernon, PA
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    Re: Mustang Bucking

    Don't think it's the gas, but you never know with todays gas. I run it out a few weeks back so the gas is new, still good thought. I haven't worked on these old cars in 25 years, went up dads to get some tools, (timing light, tach, dwell, vacuum gauge) all I could find is tach/dwell meter. I'm going up my buddies Monday to get the rest of the things I need to check it all out. Thanks for all suggestions.

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    7/27/2014 9:49 AM  #8

    GPatrick
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    Re: Mustang Bucking

    Check the condenser, and a dirty fuel filter or failing fuel pump can also be at fault - it will run well in the driveway and not deliver enough gas under load.

     

    7/27/2014 10:25 AM  #9

    boomyal
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    From: Vancouver, Washington
    Registered: 4/01/2013
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    Re: Mustang Bucking

    .....and btw, although it is not the source of your problem, those 62 secondaries might be a bit rich.  The 'book' calls for 58's in that year.

     

    7/27/2014 10:25 AM  #10

    Bullet Bob
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    From: Montrose, Colorado
    Registered: 4/01/2013
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    Re: Mustang Bucking

    Good looking car, Walt.  Hope I get to park ours next to it at the bash.

    BB

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    7/27/2014 5:58 PM  #11

    BillyC
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    From: Chesapeake, Va.
    Registered: 4/02/2013
    Posts: 965

    Re: Mustang Bucking

    Mine was doing the same thing, 66 coupe, 289, Edelbrock Performer intake, 600 cfm carb. I set the timing with a light to specs and it bucked something terrible. Set the distributor with a vac gage to acheive highest possible vac, problem solved. Thing runs like a scalded dog.

    "anyone that stops learning is old, whether at twenty or eighty"Henry Ford
     

    7/28/2014 6:02 PM  #12

    wsinsle
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    From: Belle Vernon, PA
    Registered: 4/01/2013
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    Re: Mustang Bucking

         Billy I think thats what I'm going to try next, A few guys mentioned above to advance the timing. First I thought I might have a vacuumleak, I tried to run it with most of the vacuum line disconnected. Try pulling out on a steep hill while setting on pillows and blankets with the power brakes disconnected. Nothing to lean back on to apply pressure to the brakes. That was fun!
         BB that would be really cool but time is running out. But I always work better under pressure.
         Boom I hear what your saying, this carb came with '68'. I got the 62's from a friend. Another buddy said he has some jets but just got to find where he put them. I would really like to get it on the road and running before messing with them.

    Last edited by wsinsle (7/29/2014 4:07 AM)

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