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Thread: Need help... "New M715"

  1. #1
    Join Date
    Aug 2016
    Location
    Seattle, Washington
    Posts
    1

    Default Need help... "New M715"

    Ok, so it's new to me.

    Heavily modded exterior, stock engine and tranny with just under 26k original miles.

    I getting a loss of power and backfiring whenever I need power to climb even a slight hill at any speed, any gear. No issues with idling or downhill.

    It has the stock Holley 1920 carb on it. I took it off and cleaned it but found it to be surprisingly clean already. I've read that the 1920 floats become unusable over the years and that I have pretty much zero chance of finding a replacement but that the Holley 1945 is a suitable sub.

    Help?

    -Oz

  2. #2

    Default

    Did you check the timing? Not sure off hand what it should be but im sure some one can chime in...

  3. #3

    Default

    Quote Originally Posted by Romadoz View Post
    Ok, so it's new to me.

    Heavily modded exterior, stock engine and tranny with just under 26k original miles.

    I getting a loss of power and backfiring whenever I need power to climb even a slight hill at any speed, any gear. No issues with idling or downhill.

    It has the stock Holley 1920 carb on it. I took it off and cleaned it but found it to be surprisingly clean already. I've read that the 1920 floats become unusable over the years and that I have pretty much zero chance of finding a replacement but that the Holley 1945 is a suitable sub.

    Help?

    -Oz
    Could what you're thinking of be a model 1940? I'm just curious in case the float in my 1920 is bad.

    I wonder if your running issue might have to do with a defective vacuum advance unit.

  4. #4
    Join Date
    Jan 2011
    Location
    Fernandina Beach, FL
    Posts
    3,689

    Default

    Quote Originally Posted by Nailhead View Post
    Could what you're thinking of be a model 1940? I'm just curious in case the float in my 1920 is bad.

    I wonder if your running issue might have to do with a defective vacuum advance unit.
    I don't think a stock ignitor has vacuum advance. However, it does have mechanical advance weights (doesn't it?).

  5. #5

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    Quote Originally Posted by Don Cavey View Post
    I don't think a stock ignitor has vacuum advance. However, it does have mechanical advance weights (doesn't it?).
    Correct. No vacuum advance. Just mechanical. The vacuum line going to the stock igniter is for venting the ozone.
    SFC, HQ,129th Sig Co, PAARNG, Vietnam Era

  6. #6
    Join Date
    Sep 2008
    Location
    Stevens Pointski, Wisconsin
    Posts
    1,350

    Default

    Check plug gaps and cleanliness, check points and condensor, check coil, and check timing. Check valve clearance, too.

    Fuel, check pump and fuel tank filter sock. (might not allow full fuel at higher RPM's)

    Scott
    '67 M715 '67 M725 '69 M726 (x2)

    "it's cheap and you get all you can shove in your pie-hole" --Kozmo 12-10-13

  7. #7
    Join Date
    Jan 2011
    Location
    Fernandina Beach, FL
    Posts
    3,689

    Default

    Quote Originally Posted by fishtail View Post
    Check plug gaps and cleanliness, check points and condensor, check coil, and check timing. Check valve clearance, too.

    Fuel, check pump and fuel tank filter sock. (might not allow full fuel at higher RPM's)

    Scott
    Absolutely, all of the above. When those things are correct, these trucks run well. They are not exotic.

  8. #8

    Default

    Quote Originally Posted by Don Cavey View Post
    I don't think a stock ignitor has vacuum advance. However, it does have mechanical advance weights (doesn't it?).
    Oh yeah, that's right-- mine came with a civilian distributor.

    There is, however, a vacuum hardline to the distributor that makes me think the military distributor must have had a vacuum advance. That hardline looks stock, and was plugged on mine because the vacuum advance unit had been removed and replaced with a blue zip tie.

    EDIT: Didn't see the venting reference above. Interesting.

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