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Help! i think my flathead needs a rebuild

Discussion in 'The Hokey Ass Message Board' started by merc-o-madness, Oct 14, 2008.

  1. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    ok i have a 1950 ford with an 8ba bone stock. for a week its been running lousy, i gave it a full tune up, had the carb rebuilt, checked the timing, but nothing. Then i checked to see if all cylinders were firing and i found out that cylinder number 6- driver 2nd one from the front of engine was not doing anything. Its has new a new plug, i checked the gap, i checked if i had spark to the plug all was good.

    SO then i check the compression, had it up to operating temp, and had all the plugs out...
    here are the readings i got...
    #1 120-------with oil in cylinder 145
    #2 120
    #3 120
    #4 120
    #5 110-112ish
    #6 110-------with oil in cylinder-145--this was the problem cylinder.
    #7 110
    #8 107-110ish

    I looked to see if i can see a stuck valve but it looked liked it was moving freely but it looked good and i tapped it with a hammer just for the hell of it.

    Any ideas? thanks

    heres a pic of my car so this post isnt that boring lookin
    [​IMG]
     
  2. 31ACoupe
    Joined: Nov 14, 2005
    Posts: 1,416

    31ACoupe
    Member

    Your compression looks good (for me anyway) and I would guess that a rebuild isn't the issue, more like carburetion or timing. Was it running good before? When it started running lousy what did you do? You can run a vacuum check on it, make sure the wires are sound and firing, gauge the points again, check fuel pump, all the first step things like that. It is probably something simple. A lot of the newer imported carb kits have bad power valves, you can order good ones made in the USA from several Hambers I think. If not I have a couple sources. Carbs are kind of tricky and need to be set up right too, might be air/fuel mixture.
     
  3. dalesnyder
    Joined: Feb 6, 2008
    Posts: 397

    dalesnyder
    Member

    Even though the plug sparks good out of the hole , It's no guarantee that it will fire under compression, try swapping the plug wire and plug with another cyl.
     
  4. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    well i didnt do anything to make it run bad it just happened. thats when i did one thing at a time when i tuned it up, nothing made a change. Im doubting the carb because i sent it to local guy who really knows his stuff. i didnt check the fuel pump only cause i put a new diaphram in it not too long ago. I checked the timing a couple times and tried messing with it but nothing. but i will double check everything. also will check to see if the wire sparks a differnt cylinder. other then spark i dont know what that stuff would do to make 1 cylinder not fire?
    Im also wondering if it could be a head gasket. cause one half of the motor is 120 which the book said its supposed to be. and the other half of the motor is all screwy.
     
    Last edited: Oct 14, 2008
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  5. Are you getting spark on that cylinder? can you pull the wire and hold it against the head real close to check for spark? Are the plug wires from the distributor all going to the correct cylinders? I swapped 2 wires once and it ran like shit until I figured it out. Crap gas?
     
  6. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    i can hear the spark, maybe i should double check the wires. only thing is that it ran like this b4 i changed the wires
     
  7. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    JohnEvans
    Member
    from Phoenix AZ

    With the compression numbers you are getting it ain't internal. Crossed wires ,a bad wire or a bad plug even it it is NEW !!
     
  8. Your compression numbers are within 10% so the internals are probably fine. My money is on a bad wire or maybe a cracked tower in the cap.

    Bob
     
  9. 31ACoupe
    Joined: Nov 14, 2005
    Posts: 1,416

    31ACoupe
    Member

    You can check the timing gear too, might be worn out, especially if it is fibre. I like the alum ones anyway, I like that metallic sound.
     
  10. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    JohnEvans
    Member
    from Phoenix AZ

     
  11. 302GMC
    Joined: Dec 15, 2005
    Posts: 6,199

    302GMC
    Member
    from Idaho

    Time to start looking for a vacuum leak.
     
  12. Salty
    Joined: Jul 24, 2006
    Posts: 2,259

    Salty
    Member
    from Florida

    Doubt the carb and the diapham....humans are not perfect and new parts go bad fast...eliminate the easiest problem first then work backwards...I recommend pulling the car in a dark garage and turning off the light (preferably at night) to search for the leaky ignition...you already checked the compression which I would call good...
     
  13. SlowandLow63
    Joined: Sep 18, 2004
    Posts: 5,953

    SlowandLow63
    Member
    from Central NJ

    Other than the obvious, spark, carb etc. I would look at the valves. Try a leak down test to check for a stuck, cracked, etc. problem valve. The compression numbers dont eoutta whack at all. The lowest number should be within 10% of the highest. Thats the rule of thumb I was taught and go by.
     
  14. merf
    Joined: Jul 24, 2008
    Posts: 105

    merf
    Member
    from new joisey

    I still think you need a valve job,oh yeah nice hat.
     
  15. Kustom7777
    Joined: Mar 3, 2001
    Posts: 5,176

    Kustom7777
    Member
    from Austin, TX

    compression sounds fine,,,,maybe an ignition type problem,,
    wires, coil, cap, rotor, points/condensor,,,etc,,,,,,,,,,,,
    another possibility would be a vacuum leak
     
  16. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    yeah i just checked again for spark, its got it. i tried multilple wires and plugs, the cap looks fine. the car stalls out immediatly if i cover the carb. i also checked the dwell.

    as for compression i noticed i got 2 readings, the one i showed you and another time i did it, i warmed up the car to operating temp, this time i checked one cylinder at a time with all spark plugs in except for the one i was checking. i got 80 psi at the cylinder that gave me trouble. i will post the exact numbers of all cylinders when i find the paper i wrote it on.

    as for the next step might be will prolly be spraying some startin fluid around carb and some areas to see if i got vacuum leak, takin the head off checking the valves. and replacing gasket if valves are ok. im really doubting this is just gunna be a simple fix though

    i
     
    Last edited: Oct 15, 2008
  17. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    JohnEvans
    Member
    from Phoenix AZ

    You do NOT get a true reading when you only pull one plug. The correct way is warm up the engine for 5 minutes or so ,pull ALL plugs and block the throttle wide open. You would not get the readings you posted with a valve problem !!!! You may have a intake gasket leak at the one cylinder that is giving you probs. That would be as far internal as it could be. I repeat with those readings rings and valves are working properly. Look at the inside of the cap very carefully ,replace with another if you can . Also put a NEW plug in that hole ,you cannot always tell a bad one by looking at it.
     
  18. If you partially cover the carb and it stalls, you probably do not have a vacuum leak. The idle should pick up if you have one. Is the plug in question firing at all, is it gas or oil fouled?

    Bob
     
  19. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    alright i spent the day triple checking everything, i dont think its the ignition system. also i did another compression check and i forgot to hold the throttle open last time, and i did it right this time and my compression is definatly good, only a couple were a little outta wack but not the one that im having problems with.
    also i think i described how it was running wrong b4. it really doesnt run lousy, it starts right up doesnt stall or bog. it just has a miss and shakes alot.

    now as for what i think it possibly is cause im running out of ideas of what it can be...it has compression, it has spark! so it should fire if there is gas right? now im thinking is it possible that the intake valve is stuck closed??? when i look through the spark plug hole on cylinder 6 what valve am i looking at???

    also i'd like to thank you guys for your time reading this and helping me out. i hate posting for help here on the hamb, i think its a waste for other people, but im just really stuck. so i really appreciate the help
     
  20. jamesgs4
    Joined: Aug 22, 2007
    Posts: 253

    jamesgs4
    Member
    from denver

    Man that is harsh! Suicide is NOT the answer!:eek: :D
     
  21. mudflap261
    Joined: Oct 24, 2005
    Posts: 588

    mudflap261
    Member
    from tulsa

    do a cylinder leak test that will tell you if the internals are good for sure , thenyou can onto other areas
     
  22. SlowandLow63
    Joined: Sep 18, 2004
    Posts: 5,953

    SlowandLow63
    Member
    from Central NJ

    If the intake valve was stuck closed, you wouldnt have any compression on that cylinder. You wouldnt have anything the cylinder to compress.
     
  23. AlbuqF-1
    Joined: Mar 2, 2006
    Posts: 910

    AlbuqF-1
    Member
    from NM

    I'm wondering why you think it's #6? Did you pull plug wires one at a time?

    The only thing that can drop one cylinder on an engine with good internals is ignition. Are you still running 6v, or is it converted to 12v? 6v condensers are prone to going bad.
     
  24. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    12 volt, i put a ballast resistor on. i pulled one at a time, every other cylinder made a change when i pulled it off except that one.
     
  25. Baumi
    Joined: Jan 28, 2003
    Posts: 2,490

    Baumi
    ALLIANCE MEMBER

    As you described that your engine bogs, shakes and misses humidity came to my mind... I had a problem like that on my 61 Chevy, the coil got wet when I had washed the car.
     
  26. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member


    it doesnt bog. i dont see the coil being the problem if it has spark though. i dunno
     
  27. jagfxr1949
    Joined: Jun 27, 2008
    Posts: 277

    jagfxr1949
    Member

    Since the compression numbers are reasonably good, it is mechaicaly able to run well on all eight. It has fuel. Time to take a real critical look at the distributor and cap. Look for a small carbon track to ground on the cap. It will look like a pencil line, inside or out side. They can come from scratches when putting the cap on and scraping on the rotor. Also see if the rotor cam has a flat lobe. Check for loose bushings in the distributor allowing the shaft to move around. It is possible the points are not opening enough on only one hole so that you do not have enough spark to fire the plug under load. Check the point gap on ALL lobes to make sure it is even or very close to even. Check the advance plate to make sure it is not moving around too much. The problem is no doubt electrical and that can be a bugger to find. My .02 worth.
     
  28. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    thanks sounds like it can possibly be the culprit
     
  29. 1lowtrk
    Joined: Nov 9, 2002
    Posts: 259

    1lowtrk
    Member

    I am havin the same problem! 53 merc w a rodchester 2jet.Ran like crap when i got it.Deffinate miss on #6shaking when you acelerate worse under load. So i replaced points,cap,rotor,coil,resistor and vacume advance.Plugs and wires looked new so i swaped them fom side to side to check.Motor ran the same. Checked comp. good compression on all cyls.I have noticed it runs better when it warms up but still a deffinate miss.I also hear a bit of lifter noise but im new to flatheads so this may be normal. The idle is hunting a little like a vacume leak but i found nothing external.Is it possible or common to have a vucume leak under the intake? Im assuming since the vacume advance was blown it backfired pretty good and wonder about the intake gasket. Im sorry about highjackin your thread but it looks like we share the same problem
     
  30. merc-o-madness
    Joined: Aug 23, 2004
    Posts: 1,544

    merc-o-madness
    Member

    wow sounds like the same problem, that another thing i checked, the vacuum advance, while i was checking the timing i tested to see if it advanced when i acclerated.

    this is really driving me nuts, tomorow imma check the cam in the distributor to see if all the hips are the same.
     

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