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Considering Distributor “ Upgrade “

Discussion in 'Early CJ5 and CJ6 Tech' started by Hondadoug, Sep 25, 2024.

  1. Sep 25, 2024
    Hondadoug

    Hondadoug New Member

    Pittsburgh pa
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    Can someone please enlighten me as to whether installing a vacuum advance distributor is a useful modification?
    My jeep is a 1966 cj5, f-134, with 35,000 original miles.
    I’m in the middle of bringing it back to the living, and I will probably mostly use it as a shop truck around town. As such, it will see mostly light highway duty and no really high speeds.
    What do you guys think? Doug
     
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  2. Sep 26, 2024
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

    I live South of...
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    Welcome from Michigan. I have a new F134 and a re-built F134 both have factory distributor's I see no reason to change them. I found a new short block from 1953 Military for my Jeep, it starts right up, and runs fine that way, just saying. The motor I took out is on a run in stand in my shop complete with Radiator and Harly muffler on it and it runs great with the stock distributor.
     
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  3. Sep 26, 2024
    jeepstar

    jeepstar Well-Known Member 2025 Sponsor 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sheboygan
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    no highway speeds by design, not choice :D

    i would go pertronix, if you arent happy with stock.
     
  4. Sep 26, 2024
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    Pertronix if they make for your model of distributor.
    Eliminates crappy condensor problems.
    I wouldn't worry about lack of vacuum advance.
     
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  5. Sep 26, 2024
    jeepstar

    jeepstar Well-Known Member 2025 Sponsor 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sheboygan
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    They do. Non issue. If your distributor works though I'd consider keeping it
     
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  6. Sep 26, 2024
    amboynut

    amboynut Member

    Chelatchie, WA
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    Vacuum advance requires ported vacuum source, not manifold vacuum. Do F134 carbs have a ported vacuum port?
     
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  7. Sep 26, 2024
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Welp, vacuum advance F134 distributors were used on just about all the Fheads other than those found in the CJ's.

    But back to the original question. I extremely doubt you would see any return on the investment in a vacuum advance distributor for your use. The improvement in economy is minimal. But there is definitely an improvement with an electronic distributor. As noted, no condenser but you get a hotter spark in the deal too and dispense with setting/replacing the points.
     
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  8. Sep 26, 2024
    Jw60

    Jw60 New Member 2025 Sponsor 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Just don't buy the omix electronic distributor. No replacement pickup coils or ignition modules are available. Just get a pertronix and keep the points in the toolbox.
     
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  9. Sep 26, 2024
    duffer

    duffer Rodent Power

    Bozeman, MT
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    As far as I'm concerned, that statement applies to EVERYTHING omix markets. Universally crap.
     
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  10. Sep 26, 2024
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    We could have a really fun drunken argument about that :D
     
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  11. Sep 26, 2024
    CHUGALUG

    CHUGALUG Member

    Silverton, OR
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    Lets ,look at this logically. Almost every US made auto from The late 1930's to the 1980's used a Vacuum advance type distributor. So one would logically conclude there was some reason for this timing altering device. Wouldn't a person?

    Better drivability better mileage, are the two things that come to mind.

    As to the idea an electronic distributor producing a hotter spark!!! NO the coil will only produce the amount of voltage required to jump the gap. The only way to have a "Hotter" spark is to have a bigger gap or multiple gaps (like with a booster gap plug) The distributor is nothing but a distribution switch. And a trigger to tell the coil when to collapse the field and produce the voltage to jump the gap.

    A distributor with a Petronix trigger unit in it will make the coil produce no more voltage then an old fashion set of points. It will how even be a more accurate trigger. Same with any electronic distributor.
     
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  12. Sep 26, 2024
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

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    You, Sir, are a Party Pooper :(
     
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  13. Sep 27, 2024
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
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    The Omix distributor might be the one part they sell that actually works. I have installed about a dozen of them now. Did have one that was a dud out of the box but overall they really work well. Huge improvement especially on cold startup. Beats the hell out of the points and condensers that are available today.
     
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  14. Sep 27, 2024
    Jw60

    Jw60 New Member 2025 Sponsor 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Mine were both duds out of the box and within a very short amount of time. one got a Toyota pick-up coil and 4 pin hei module to fire a small cap hei coil.
     
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  15. Sep 27, 2024
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    So, you are saying that Jeep engineers had no idea what they were doing? Or unaware of what "every US" automaker was doing?

    Or is it possible that Jeep engineers recognized that their vehicles had a unique set of needs and design parameters, quite unlike the mass of highway-only vehicles? And thus made "logical" decisions that ultimately led Jeeps to have outlived and outsold nearly every other US auto company?
     
    Last edited: Sep 27, 2024
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  16. Sep 27, 2024
    Jw60

    Jw60 New Member 2025 Sponsor 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Do any carborated tractors run vacuum advance?

    Our Chrysler slant 6 powered haybine was plugged on the manifold.
     
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  17. Sep 27, 2024
    amboynut

    amboynut Member

    Chelatchie, WA
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    The purpose of a vacuum advance is to momentarily retard timing to reduce detonation (pinging) when the throttle is suddenly opened under acceleration.
    Governor controlled constant speed engines, such as tractors, generally don't experience sudden throttle position changes under load, hence no need for a vacuum advance.
     
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  18. Sep 27, 2024
    Fireball

    Fireball Well-Known Member 2025 Sponsor 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    You can't say that and dismiss the other possibility: They knew it was better, but the bean counters didn't want to spend the money on it.

    Because it does that, it allows the engine to run with more advance in low load (non-ping prone) situations to increase efficiency. With mechanical only advance, you have to max out at 30ish degrees (depending on engine) to prevent detonation in all circumstances, with vacuum advance, it can be up near 40 degrees under low load and back off to 30 under high load to prevent detonation. I'm sure you know that, I'm just adding clarity for others.

    Ported vacuum isn't a requirement. There are many cars that came from the factory with vacuum advance hooked directly to manifold vacuum. Ported vacuum advance became popular to meet emissions requirements by retarding spark at idle to increase exhaust temperature. https://www.motortrend.com/how-to/1...now-about-vacuum-advance-and-ignition-timing/
     
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  19. Sep 27, 2024
    Jw60

    Jw60 New Member 2025 Sponsor 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    :shrug:
    The jeep engineers definitely had a few oversights... like the recirculating heater with no actual inlet on the cabin side to actually recirculate from.

    In my opinion they simply treated the 4cyl jeep as a workhorse / powerplant.. with the pto options, plows etc. It's like wal-mart giving you a 2amp hour battery instead of 5amp hour on the name brand goods. Or my dang camper stove that needs a lighter when everything else is dsi.

    It's also another thing to crap out or gumup.bon the 134. The way they did it was a joke almost as good as a model t.
     
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  20. Sep 27, 2024
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    Hmmm. That's what a stock CJ5 was back then, a workhorse that could also be driven as a personal vehicle if need be. As a 16 year old in '67 I loved my stock '59 CJ5 as did my friends, and I drove it to school everyday. :shrug:
     
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