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Tune up guru needed!

Discussion in 'Early CJ5 and CJ6 Tech' started by Thunderpig, Jul 1, 2008.

Page 1 of 2
  1. Jul 1, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
    Joined:
    Mar 28, 2006
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    259
    Hello all,

    Just finished up installing my (2nd) rebuilt F-134. Started it up set the timing at 5 degrees BTDC (it was dead on). I have a Weber 32/36 DGV carb which requires a fuel regulator. I just bought a new one and installed it . Set it to 2.5 and tried to start it. No go. bumped it up to 3 then 4 then 5 and finally it started up. It seems to backfire a little bit and so I screwed the carb adjustment to stop and then out 2 turns which I think is supposed to be the factory setting. Still the same. Runs but hard to keep running and it has a slight backfire to it every few seconds. Pulled a plug and it is black. Brand new plugs an hour ago. Points are Pertronix. Rechecked timing and dead on 5 degrees. Altitude is 5000 feet.

    My diagnosis is too much fuel, not enough air. But why I have no clue! Ideas?:?
     
    Thunderpig, Jul 1, 2008
    #1
  2. Jul 1, 2008
    Homebrew2

    Homebrew2 Member

    Dunlap, CA
    Joined:
    Aug 17, 2007
    Messages:
    511
    I'm sure sorry to hear of your continued trouble.

    Hopefully someone who is a guru, not a hack like me, will reply.

    Just my thoughts ...
    1, a Weber does not require a regulator. Mine works fine w/o one.
    2, I could care less about "idle". Mine idles rough, but at ~650 ... great compression braking, which is all I care about at idle.
    3, At anything above idle, it screams. After a nice run around the mountain neighborhood (20 miles, many times), the plugs are clean.
    4, I have not yet driven mine @ 5k' consistantly, only 2-3k', consistantly.
    5, From my research, Weber 32/36's are prone to small particulate clogging of the air bleeds. Which would contribute to richness. I dunno though.
    6, my 32/36 IDLE mix screw was set to 1.25 turns from the factory. Again, I don't care much about idle but, have adjusted idle speed as necessary to keep the fire lit.
    7, @ 5k' elevation, it may like 7° initial advance better than 5°.

    :beer:
     
    Homebrew2, Jul 1, 2008
    #2
  3. Jul 1, 2008
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
    Joined:
    Mar 4, 2003
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    5,474
    Zim - did you rebuild the carb lately? It might be worth a quick dissasemble, clean and float check. It's been a long time since I futzed with the old 4 cyls (as in when we were sophmores when I put my V6 in - god were getting old) but I don't remember having a regulator as well. I also remember having to lean it out quite a bit and jetting smaller for the alt. I also believe the idle circuit is different from the running, so don't be afraid to run her for a bit on the road and see how it idles once its warm.
     
    Warloch, Jul 1, 2008
    #3
  4. Jul 1, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
    Joined:
    Mar 28, 2006
    Messages:
    259
    Where did I just see that the weber needed a 2.7psi fuel flow regulator? Just yesterday on this forum somewhere, now I can't find it. That's the reason I bought one. I thought it might solve me problem!

    I bolted this carb on right out of the box 8 years ago and it ran great up to 10K feet! I was in Baggs WY then alt 6200. No real adjustments. Had some mechanic "go through the carb" a few months ago he said it was fine, but then again he's the guy that built my last engine and screwed it up.

    What's interesting is that when I turn the mixture screw... nothing really changes either way!???

    I'll pull off the regulator cuz I can't hardly start it up now.
    I think I'll find a new mechanic, but around here no one works on carburetors anymore!

    Oh brand new fuel pump. without vaccum ports for wipers. shouldn't matter.
     
    Thunderpig, Jul 1, 2008
    #4
  5. Jul 1, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
    Joined:
    Mar 28, 2006
    Messages:
    259
    Question:

    Mixture screw tightening = less air, more fuel? or the other way around?
     
    Thunderpig, Jul 1, 2008
    #5
  6. Jul 2, 2008
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
    Messages:
    4,275
    The Solex carbs are very finicky as to the fuel pressure, not nearly so much for the Weber.

    IMHO, reading the plugs after idling is a waste of effort, it only shows what the idle mixture is and you can set that by the ear/nose method or with a vacuum gauge. If you want to really see how your carb is jetted, you need to do the WOT test.

    What's the WOT test?

    Start the Jeep and let it warm up to operating temp. Find a relatively straight stretch of highway and run the Jeep HARD (WOT) through the gears. Once you are at a good speed at WOT in high gear, shift to neutral and cut the engine. Coast over to the berm and pull a couple of plugs to see how they are burning. If they are still black and sooty then you need to cut back on the main jets, too white and crusty and you need to open up the main jets a size or two. The main jets are sized to provide the best A/F mixture under *most* conditions. If you can get it to burn the plugs nice and even at WOT then it should run nicely just about anywhere else other than idle. The idle equality is still at the mercy of the idle screws, and you need a vacuum gauge to set those properly.

    HTH. ;)

    <edit> The idle mixture screws control fuel, not air. Screw ing them out makes the idle richer and vice-versa.
     
    Last edited: Jul 2, 2008
    w3srl, Jul 2, 2008
    #6
  7. Jul 2, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
    Joined:
    Mar 28, 2006
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    259
    A little more info from what I discovered tonight. It runs really rough at low rpm, hard to start but once it's running I put my hand over the carb partially blocking air flow and it immediately responds, sounds crisp clear and speeds up rpms. Sounds great actually.

    So I'm getting too much air somehow? How shall I proceed? Could it be a vacuum leak? I don't think my hard line is leaking, I took pains to ensure it wouldn't suck air at each connection. Maybe around the carb base somewhere. I used all my carb cleaner cleaning it up is there anything else I can use to spray around the base?
     
    Thunderpig, Jul 2, 2008
    #7
  8. Jul 2, 2008
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    Either use a vac guage or start by turning the air fuel mixture screw out then slowly screw it in till you hear the eng stumble and back it out 1/4 turn.
     
    blevisay, Jul 2, 2008
    #8
  9. Jul 2, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
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    Mar 28, 2006
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    I'll try that!

    Thanks Bill
     
    Thunderpig, Jul 2, 2008
    #9
  10. Jul 2, 2008
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    If you have a vac guage just tune the mixture screw for bet vac.:)
     
    blevisay, Jul 2, 2008
    #10
  11. Jul 2, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
    Joined:
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    Don't have a vacuum gauge. Guess I'll invest in one. Still doesnt' run right. Unless I have the choke on almost full or my hand over the carb.
     
    Thunderpig, Jul 2, 2008
    #11
  12. Jul 2, 2008
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    You did say the plugs were black.........time for a new set. (trust me on this)
     
    blevisay, Jul 2, 2008
    #12
  13. Jul 2, 2008
    Homebrew2

    Homebrew2 Member

    Dunlap, CA
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    If you can get it lit, and keep it lit, drive it ! The question is: is it a lean idle condition or, a lean condition overall.
     
    Homebrew2, Jul 2, 2008
    #13
  14. Jul 2, 2008
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    Pulled a plug and it is black.
     
    blevisay, Jul 2, 2008
    #14
  15. Jul 2, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
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    Fired it up ran it about a mile... ran GREAT but with the choke on. Pulled a plug again and it is lightening up. The tip of the plug is tan now but the rest of the plug is still black but drier.

    Clear as mud ?
     
    Thunderpig, Jul 2, 2008
    #15
  16. Jul 2, 2008
    Homebrew2

    Homebrew2 Member

    Dunlap, CA
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    Aug 17, 2007
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    Brand new plugs 24 hours ago (first post, or so) ... I know, I don't get it either. Yesterday we had a rich condition, today we have a lean condition ... :(
     
    Homebrew2, Jul 2, 2008
    #16
  17. Jul 2, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
    Joined:
    Mar 28, 2006
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    I think it was rich yesterday because it was getting too much air and not getting good ignition. Today all I did was put my hand over the carb intake. Changes the mixture and the engine likes it.and it runs great, but I can't go around with choke on all the time.
     
    Thunderpig, Jul 2, 2008
    #17
  18. Jul 2, 2008
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    Plugs foul.
    Champion J8c are infamous for fouling under a rich condition. Once fouled using the choke will help it run better.

    BTDT

    :beer:
     
    blevisay, Jul 2, 2008
    #18
  19. Jul 2, 2008
    Thunderpig

    Thunderpig Member

    Parachute, Colorado
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    Ok it's only a few bucks. These are Autolite 306, well anyway. But what I'm confused about is ... whats the cause of the problem?
     
    Thunderpig, Jul 2, 2008
    #19
  20. Jul 2, 2008
    blevisay

    blevisay Oh Noooooooooooooooo! Staff Member

    Portland Tn.
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    Me thinks you had the carb too rich and fouled the plugs. (assuming the carb was looked at by said mechanic and found to be in working order)
     
    blevisay, Jul 2, 2008
    #20
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