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Duantless Running Lean

Discussion in 'Early CJ5 and CJ6 Tech' started by Brislin06, May 14, 2022.

  1. May 14, 2022
    Brislin06

    Brislin06 Member

    Pennsylvania
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    Hello everyone, I have a 69 cj5 with a 225 v6 the only upgrade is an HEI. My question is I pulled a few spark plugs and they are completely white it has a Rochester 2g (the correct one when I run the numbers) I also have ac delco plugs gapped at 45. My first thought was the pull the carb and check the float but otherwise it runs absolutely great. If the float level is okay would my next step
    Be to go up a jet size or 2? Anyone had a similar problem? Thanks I’m advance
     
  2. May 14, 2022
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
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    Lockman likes this.
  3. May 14, 2022
    Brislin06

    Brislin06 Member

    Pennsylvania
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    I apologize I have to change the post I meant to say lean
     
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  4. May 14, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    I kind of thought the same thing initially, but then the OP also mentioned going up a jet size, which would be the correct increase in fuel for the lean condition.
     
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  5. May 14, 2022
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Ah yes. Makes sense now. Yes you may want to go up a jet size or two.
     
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  6. May 14, 2022
    Brislin06

    Brislin06 Member

    Pennsylvania
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    Okay thanks, is that a common problem with todays gas?
     
  7. May 14, 2022
    Lockman

    Lockman OK.....Now I Get It . 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Silver Hill,...
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    No ..... The opposite . The ethanol lowers the octane , burning cooler, richer & less efficient, IMHO. What's your temp gauge running at & what heat range are your AC plugs ?
    Up a Jet size will work , but it could be as simple as the wrong plugs ?
     
  8. May 14, 2022
    Brislin06

    Brislin06 Member

    Pennsylvania
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    I have a 160 thermo depends on what kind of driving but somewhere around that 170 180
    If I’m putting around fire roads on the interstate which is rare 160 it will get hot if I idle for a long time no overheating. I run an AC delco R43s plug in it.
     
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  9. May 14, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    those are heat range 3...the coding is
    R - resistor plug
    4 - 14mm thread
    3 - heat range

    FWIW its worth, I found the R43 to be too cold...IIRC correctly, the factory spec may have been R44, but not sure if you can get those anymore, and the computers now cross-list R43 in place of R44. I ended up with R45 and that works well for me (high elevation with tendency to run fuel rich)....but in your case, you are either running too lean or are too high of a heat range. Given the R43 plug, its seems to be indicating a bit too fuel lean. Do you know what size jets your are running in the R2g? 51s would be OEM for most normal elevations (0-2500'). If you are running 51 jets and R43 plugs, and are still running lean, then maybe something in the carb isn't supplying enough fuel - maybe the PV is sticking. Normally, if the PV or a-pump is not functioning, you'll get some sort of stumble or 'hiccup' when under full throtte as its needing more fuel. Also, make sure when you read plugs, the engine was running at full rpm (not idle) and then is shut off quick - don't let it idle.

    Also - just for clarity, please don't confuse heat range of the plug and thermostat temp
     
    Last edited: May 14, 2022
  10. May 14, 2022
    Brislin06

    Brislin06 Member

    Pennsylvania
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    I will take the carb off tomorrow, I’m pretty sure they are 51s. I have a brand new set of 53 laying around think that would a mistake skipping 52s right to 53 or not much of a difference
     
  11. May 14, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    JMO, but before going to larger jets, I'd look for a root cause first as my first thoughts are that its not simply a jetting issue....most of these jeep run rich, especially with modern fuels, and most of us have had to lean our engines out. Doesn't mean jetting isn't the cause, but I'd exhaust a few other inquiries first...ethanol varnish restricting fuel flow in the various passeways, maybe raising the float a bit, checking the PV, checking for vacuum leaks at the base of the carb or intake manifold gasket etc.
    If you choose to go the route of jetting....jets are cheap, and shipping is more than the set of jets, so just order both and pay the same shipping once.
     
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  12. May 14, 2022
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    Not necessary to remove the complete carb to swap jets. Just take the top off and lay aside.
    Do you know what jets are inside currently ?
     
  13. May 14, 2022
    jeepdaddy2000

    jeepdaddy2000 Active Member

    Eagle Point oregon
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    Signs of lean burn:
    Backfiring through the carburetor
    bucking under acceleration or cruise.

    If you suspect your lean, try closing the choke a tad and see if there is any improvement.
     
  14. May 15, 2022
    Brislin06

    Brislin06 Member

    Pennsylvania
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    So I took fino cj’s advice I sprayed around the intake and carb base with carb choke cleaner to look for vacuum leaks. I didn’t find anything around there, but It did bog down when i sprayed the on passenger side of the carb the hole right in the center is where it’s leaking from it’s a small leak when I put my finger Over it I could not feel anything. Anyone else somehow cap this hole off. I know that it’s that the shaft that the butterfly’s are attached to.
     

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  15. May 15, 2022
    homersdog

    homersdog Tulsa, Ok 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    I have had this same leak before. I made a disk by cutting off the flange of an appropriate sized pop rivet, then stuck that over the hole with some RTV. It held up for many years.

    Just went and looked, it's still there but I have since switched the RTV to JB weld

    [​IMG]
     
    Last edited: May 15, 2022
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  16. May 15, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    How loose or sloppy is the butterfly shaft in that hole? It's been awhile since I messed with my 2g, but I was working on my qjet more recently and it's not uncommon to need to rebush the pivot hole for the butterfly rod....maybe pull the carb and inspect the butterfly and base plate? might be interesting to run a vac gauge to manifold and read vacuum at idle with the bushing hole as is versus with it plugged (finger with a rubber glove over the hole). Keep working the problem a little bit at a time....but with that said, I'm wondering if you are only running lean at idle due to this little leak, and it doesn't take long for it to change the plug color. It may not be pulling enough fuel through the idle circuit. Be sure to confirm the idle screws are working, as well as the throttle plate goes all the way closed at idle.
     
  17. May 15, 2022
    Brislin06

    Brislin06 Member

    Pennsylvania
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    Fino cj you have a good point it could be leaning itself back out at idle. I took a carriage bolt cut it of and filed the square part ontop so it fit snug and put some jb weld on it. When it sets up I’ll test it out.
     
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