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  •  » Car is bogging hard on acceleration

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    7/12/2022 4:51 PM  #1

    BTaylor
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    From: Carrabelle, FL
    Registered: 4/02/2013
    Posts: 127

    Car is bogging hard on acceleration

    I just put a new carb intake and distributor in my Cougar.
    347 stroker
    holley 4 barrel
    I just removed an EFI system from the car and put on the new parts. The car will start and idle fine and if I drive around and just barely accelerate it runs fine. If I push down any more it bogs hard and if I don't lift it will backfire. It will drop back and idle fine.
    I have double checked TDC and set timing. Checked and do not have any vacuum leaks,
    If anyone has any help for me I am all ears.
    Thanks in advance.
     

    68 Cougar XR7 347 stroker T5 3:80
     

    7/12/2022 5:29 PM  #2

    MS
    Forum Originator

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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,248

    Re: Car is bogging hard on acceleration

    Larger power valve and jets, typically.  What is the timing set on?

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

    7/12/2022 6:36 PM  #3

    BTaylor
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    From: Carrabelle, FL
    Registered: 4/02/2013
    Posts: 127

    Re: Car is bogging hard on acceleration

    Initial timing is 12 
    Holley 670 straight out of the box.

     

    68 Cougar XR7 347 stroker T5 3:80
       •Thread Starter
     

    7/12/2022 6:39 PM  #4

    Rufus68
    I FYI 24-7

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    From: Knoxville, TN
    Registered: 4/26/2017
    Posts: 889

    Re: Car is bogging hard on acceleration

    If you haven't already put an AFR gauge, do this first.  It will show you if it is lean bog or a rich bog.

    1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
     

    7/12/2022 6:45 PM  #5

    Rufus68
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    From: Knoxville, TN
    Registered: 4/26/2017
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    Re: Car is bogging hard on acceleration

    I recently put a new Summit Racing 580cfm carb on.  Out of the box, it came with a #62 primary jet.  This turned out to be very lean for my 302.  I'm currently at a #64 jet on the primary and I'm still deciding if I should go to a #65 or leave it.  There are several factors that affect AFR such as engine temperature, timing, idle screw setting, and float level.  The #64 might be perfect though I just haven't had the time to put the miles on it yet to be sure.

    Point is, without my AFR gauge knowing exactly what is going on would not really be possible.
     

    1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
     

    7/12/2022 6:48 PM  #6

    Texas!
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    Registered: 6/27/2014
    Posts: 231

    Re: Car is bogging hard on acceleration

    It sounds to me like it's going lean when you open it up. Larger squirter, different pump cam, power valve that opens sooner.

     

    7/12/2022 6:56 PM  #7

    Rufus68
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    From: Knoxville, TN
    Registered: 4/26/2017
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    Re: Car is bogging hard on acceleration

    That is exactly what having an AFR gauge might tell him.

    Also, having a vacuum gauge will let him know more precisely which carb circuit is actually being used.

    Last edited by Rufus68 (7/12/2022 6:58 PM)

    1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
     

    7/12/2022 7:43 PM  #8

    BTaylor
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    From: Carrabelle, FL
    Registered: 4/02/2013
    Posts: 127

    Re: Car is bogging hard on acceleration

    Anyone have a spare AFR gauge??
     

    68 Cougar XR7 347 stroker T5 3:80
       •Thread Starter
     

    7/12/2022 8:47 PM  #9

    Rufus68
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    From: Knoxville, TN
    Registered: 4/26/2017
    Posts: 889

    Re: Car is bogging hard on acceleration

    https://www.amazon.com/AEM-30-0300-Wideband-Sensor-Controller/dp/B0184TSI84

    1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
     

    7/12/2022 8:57 PM  #10

    Bentworker
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    Registered: 9/17/2017
    Posts: 472

    Re: Car is bogging hard on acceleration

    If your initial is 12 degrees what is your total timing?

    What distributor are you running?  Does it have vacuum advance?  How early are you all-in with your mechanical advance?  If you are running vacuum advance is it connected to ported or manifold vacuum?

    I’m with everyone regarding the AFR gauge.  It is a very useful tool.

     

    7/12/2022 9:24 PM  #11

    6sally6
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    From: Surfside Beach,SC
    Registered: 4/02/2013
    Posts: 6,852

    Re: Car is bogging hard on acceleration

    'Just' knowing the initial timing .........really doesn't give the full picture as to what's going on.
    Total timing 32-34-36 degrees AND what RPM total advance occurs.......then you have some facts to work with.
    Going from sluggish and slow acceleration........to crisp & powerful is what you get when tuning with TOTAL advance.
    I've talked about it a bunch.........and most guys that learn and tune with total advance are TOTALLY (pun intended!) blow away!
    (It's that bigga deal!)
    Most "carb issues" are timing issues.
    6sal6

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

     

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