Advice needed!!! Smoke on one side of exhaust

Discussion in 'Small Block Mopar Engine' started by 65valiantwin, Aug 10, 2018 at 8:53 AM.

  1. 65valiantwin

    65valiantwin Active Member

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    Hey guys, built a new engine about 2 years ago as follows:

    360 stroked to 408
    Comp ks671-20 cam. Duration 284/291, Lift .484/.484 , LSA 108
    LD340 intake with divider ground most of way down
    new edelbrock performer 600 carb (I know it's too small, new one on way)

    Anyways, here's my issue. It's run maybe a total of 25 minutes since rebuild, but recently when we've been setting timing, etc. we're getting rich exhaust (unburnt fuel, NOT oil) out of only one side (Passenger) after it warms up, completely normal exhaust out of the other side. Not running H pipe, exhaust straight back from headers. The engine is running/sounding great otherwise. I cannot figure out for the life of me what the problem could be, i'll be pulling plugs/compression testing tonight but was wondering if anyone had any ideas?

    Thanks in advance
     
  2. 318willrun

    318willrun Stomper 4x4... we kept energizer in business

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    dead plug wire on one side? I seen this once on a new set of wires.....
     
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    • rumblefish360

      rumblefish360 so close yet so far away

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      Double check valve seals on that side of the engine.
       
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      • diymirage

        diymirage HP@idle > hondaHP@redline FABO Gold Member

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        Got a timing light?
        You can check the wires on the suspect bank by putting the light on there (your not checking time, just spark)

        Next, pull the valve cover and see what the rockers are doing?
         
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        • RustyRatRod

          RustyRatRod Just another dumbass. FABO Gold Member Technical Editor

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          How do you know what it is or what it's not? Have you had it analyzed? Never simply assume. It can fool you. I go along with what rumblefish said. I would be checking the valve seals on that side. It's easy and costs nothing to check.
           
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          • '63GT

            '63GT Well-Known Member

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            Can't discount the valve seal warnings....
            Have you checked your wires? You may have pulled a connector loose from the wire when you removed them for the rebuild. Ohm test them. Or just do a 'balance test' to isolate the offending cyl/wire/other. It will narrow it down for you, at least.
             
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            • inertia

              inertia Well-Known Member

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              What happened with the old engine.? ?
              Did it have a bad cylinder that side or did anything happen to fill one exhaust pipe with oil or coolant ? ?
               
            • 65valiantwin

              65valiantwin Active Member

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              Hey Inertia, thanks for your reply, it was a "new" build, just got the core block from someone and built from there, wasn't my engine previously. There isn't anything in the pipes.
               
            • nm9stheham

              nm9stheham Well-Known Member

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              Certainly sounds like a weak firing cylinder; a dribble out of one side of the carb ought to show up on both banks with that intake type. Just some more things to check:
              - Check each spark plug wire for resistance end-to-end and see if one is much higher in resistance than the rest.
              - Look at the valve lift on all cylinders as suggested. (Not always easy with hydraulics if they leak down any.)

              What plugs do you have? Resistor or non-resistor?
               
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