Low compression, miss

Discussion in 'General IH Tech' started by paintguy, Aug 20, 2020.


  1. paintguy

    paintguy Farmall Cub

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    First off I'm new to ihc Engines but have played with other flavors. Acquired a 1973 scout with the 345 v8 auto. Purchased new battery, cleaned all connections (hate wireing Issues). Point were burnt up, replace points, condensor, rotor, cap. Installed new coil as their was not one, new plugs and wires. Engine would turn over but still sprayed cylinders with oil to lube. Compression check all cylinders have close to 110lb except #3 which has 90lb. Engine starts and idles but has a dead miss. Remove #3 wire no change. I'm guessing a burnt valve but not familiar at all with theses engines. When I pull the heads is their anything I need to look for or replace while I'm in it ? Thanks for the help just a newbie to these and don't want to miss something.
     
  2. jeff campbell

    jeff campbell Lives in an IH Dealership

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    Put a new plug in # 3. See if it changes or not. If not, then get at it.
     
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  3. 1975IH200

    1975IH200 Y-Block King

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    The IHC engine is the same as the others. Troubleshoot like you would any other gasoline-spark ignition engine.
    Correct as necessary.
    I don't understand your thought process of a "dead cylinder" equals a head removal without further investigation.
    But it is your engine, so do what you will.
    Over and Out.
     
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  4. Darrel

    Darrel Dreams of Cub Cadets

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    OP said new plugs and wires installed so if pulling a wire doesn't affect how it runs that's a pretty good clue. :) If you want to narrow it further before pulling the heads you can run a leak down test. 110 sounds tired - if it turns over fast, gauge is accurate, and the throttle was wide open.
     
  5. mallen

    mallen Y-Block King

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    Did you put some oil in the cylinder and see if the compression comes up? Had the vehicle sat for a while before you started it? If so it might improve with time. I like to put oil in all the cylinders, run it, and repeat every couple days. I cant say it works or not , but my thought is, a nice hard oily residue of of carbon buildup can only smooth over rusty surfaces and help seal things.
     
  6. Jeff Jamison

    Jeff Jamison Lives in an IH Dealership

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    Could be as simple as a bent push rod off of a lifter.Seen that happen on alot of IH engines that have sat for extended time.Pull valve cover and check.
     
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  7. paintguy

    paintguy Farmall Cub

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    Lots of help, Thanks I have oiled the cylinder a few times and yes it has sat for a few years. Did not really want to rebuild the complete engine , when I pull the valve cover off I will see how deep I can expect to go. Again thanks for all the suggestions.
     
  8. RinTX

    RinTX High Wheeler

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    First double check and make certain #3 is getting a nice spark. Then I’d look inside the valve cover. There was a thread just this week with a bent pushrod.
     
  9. wjajr

    wjajr Binder Driver

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    Put compressed air to #3, listen for air capping through carb and exhaust. If you hear air escaping from intake or exhaust side than you have a valve problem. Could be a stuck or burnt valve, push rod bent, off spec valve lash adjustment if this is a solid lifter engine. If you hear air escaping from crank case, than there could be a broken ring, if engine has sat for a length of time, corrosion on cylinder walls will prevent good sealing. If there is minim corrosion of cylinder walls, squirting in some transmission fluid letting it soak over night, and running engine for a few days may re-seat the rings.
     
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  10. paintguy

    paintguy Farmall Cub

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    Have to ask guys, this transmission looks like a mopar 727, anyone ever put a sb dodge engine in one of these? Can a dodge 727 trans be adapted to the transfer case ? I know its sacrilegious but have to ask?
     
  11. scoutboy74

    scoutboy74 Lives in an IH Dealership

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    There have been a number of Scouts converted to Mopar power. The aluminum TF case as you probably already know, is specific to engine make and family. The IH versions in 4x4 Scouts have an adapter housing on them with a reverse Texas pattern to interface with the passenger drop Dana 20 t-case. What you can do is gut the Mopar TF case that fits your Mopar engine and gut the IH TF case and assemble the output guts and adapter housing into the Mopar TF case. Now you have a unit that will agree with your engine and your T-case.
     
  12. paintguy

    paintguy Farmall Cub

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