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Vacuum Advance On An L Head?

Discussion in 'Flat Fender Tech' started by garage gnome, Apr 28, 2020.

  1. Apr 28, 2020
    garage gnome

    garage gnome ECJ5 welder

    Western MA
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    Would adding a vacuum advance to an L head help at all with performance? Especially with a better carb?
     
    jeep2003 likes this.
  2. Apr 28, 2020
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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    Did you ever try a progressive 2bbl carburetor?
     
  3. Apr 28, 2020
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    Fuel economy and emissions might improve. Peaks won't change
     
  4. Apr 28, 2020
    PeteL

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

    Hills of NH
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    I seriously doubt it. But you could try putting the intake valves in the head...
     
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  5. Apr 28, 2020
    garage gnome

    garage gnome ECJ5 welder

    Western MA
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    That I did. ;) Forest Service 3A Weber carbs are progressive 2bbls.
     
  6. Apr 28, 2020
    garage gnome

    garage gnome ECJ5 welder

    Western MA
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    I found a vacuum advance distributor for $75. Thought it might be worth a shot, but I'll save that money.
     
  7. Apr 28, 2020
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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    Weird I didn’t get notifications :susp:

    I have a vacuum advance distributor but I haven’t done anything with it yet.
     
  8. Apr 28, 2020
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
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    I didn't get notifications neither.

    The vac advance distributor I had from a truck f-134 didn't impress me. It just rotated the whole distributor in the hole and I didn't care for that idea. Now a waterproof 4cyl bowtie hei with vac advance would solve all that.
     
  9. Apr 29, 2020
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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    I have a sbc distributor I’d like to try that with
     
  10. Apr 29, 2020
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Given the dismal economy of the original L134's in CJ's, I seriously doubt you could see a statistical significant difference in mileage. I'm not sure why Willys used the vacuum advance in the wagons/pickups/FC's but I doubt there was much advantage there either. Emissions? If that was a requirement, we wouldn't be driving any of these.
     
  11. Apr 30, 2020
    CHUGALUG

    CHUGALUG Member

    Silverton, OR
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    May 11, 2019
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    Our 134L from a 58-59 DJ-3A has had a Vacuum advance distributor since the 60's its from a 61 FC-150 and YES it does improve the driveablity of the Jeep As I have no knowledge of what the mileage would be without the advance to compare I can't say what it changed. But logic says if damn near everything uses a Vacuum advance there must be a reason. I currently have two IAT-4405 Distributors one will be set up with a Petronix unit (I will have to figure that out as there is no direct fit kit) the other will be conventional with points. I am also running a Weber DGV-5A on an Aluminum intake with a Tri Y design Header. Engine has not been started yet.
     
  12. May 29, 2020
    jeepdaddy2000

    jeepdaddy2000 Active Member

    Eagle Point oregon
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    Engines will tolerate more advance under light loads, equating in added economy and performance. Since vacuum advances are load sensitive, they can provide added measured advance.
     
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