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Thread: Challenges with 4 Barrel 80457

  1. #1

    Default Challenges with 4 Barrel 80457

    Hi there. I've got a 4 barrel 80457 with vacuum secondaries. It's mated to a pretty stock Ford 302 via a Edelbrock manifold. I have a number of challenges and I wonder if anyone here can help.
    1. The electric choke seems to do nothing. The choke is always open and never closes, but so far it starts cold just fine.
    2. The vacuum secondaries never seem to open. I rev the engine up high and they seem to stay closed. I'm guessing this is a damaged diaphragm, but I'm actually struggling to work out which diaphragm part number fits this.
    3. Even at tick-over the secondary nozzles seem to drip fuel into the barrels.
    4. Despite all this it seems to run OK, but when it's warm the tick-over in drive sometimes drops very low, and it starts to run lumpy. I can't see any vacuum leaks anywhere but I can check again.
    5. At the corner where the fuel pipe enters the carb beneath the accelerator pump there seems to be a slow leak of fuel onto the top of the manifold. It used to have an adjustable flow limiter thing on it, but I swapped it out for a fuel filter instead. Not sure if this actually did anything intelligent.
    6. Fuel consumption has just gone up a lot just recently.
    7. When it gets a bit hot it can take a lot of cranking to get it to fire again. I have just bought a half inch heat isolator which I hope will solve this. I also have bought a rebuild kit and another electric choke.

    Anyone got any thoughts about any of this? Thanks, Jamie.

  2. #2

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    The electric choke seems to do nothing. The choke is always open and never closes, but so far it starts cold just fine.
    Need to make sure you have switched +12V going to choke. It should activate based +12V and on temperature (COLD). Make sure all of the linkage is fee and hooked up properly to the Electric Choke on the side of the carb. Watch first three videos at this link to become familiar with choke operation and settings
    https://www.youtube.com/results?sear...oke+adjustment

    The vacuum secondaries never seem to open. I rev the engine up high and they seem to stay closed. I'm guessing this is a damaged diaphragm, but I'm actually struggling to work out which diaphragm part number fits this.
    You can't free rev the engine and expect the secondaries to open up. You would have to hold the throttle at 3/4-WOT while in Neutral for the linkage to be activated to allow the secondaries to open, and then you have to wait for the engine to BUILD VACUUM to open the secondaries. By the time this happens you'll easily have red lined your engine and possibly damaged it. If you bought this carb new Holley has warnings about doing this. There are springs you can change to adjust the opening rate of the secondaries. Be careful of running to little of spring and allowing the secondaries to open "TOO soon". It will bog the engine down.

    Even at tick-over the secondary nozzles seem to drip fuel into the barrels.
    I don't know what you mean by "TICK-OVER". But vacuum is what causes the boosters to flow fuel, so if there's minimal air amount flowing over the booster it could cause them to drip.

    When it gets a bit hot it can take a lot of cranking to get it to fire again. I have just bought a half inch heat isolator which I hope will solve this. I also have bought a rebuild kit and another electric choke.
    It could be getting hot causing fuel to flow when you turn the car off, hence the hard hot start. Make sure you float level is not too high and if you can try lowering your fuel level in your bowls just a bit. The isolator will help with the heat issues.

  3. #3

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    Hey, that's a huge help, thanks. Tick-over is a British way of saying idle. Sorry, I forget some terms don't translate despite living in San Francisco for much of the 90s. I'll check out the videos and look at what's happening with the choke. Much appreciated. Jamie.

  4. #4

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    Ahh OK...that's better. So if you have the ability to adjust the rear butterflies, they might be open enough so allow air to pull through the secondaries. That will cause the booster to drip fuel. Also, double check float level here. If too high it will drip/flow out of booster as well.

    When you adjust the carb, make sure you make idle adjustment and any changes on a WARM engine. I forgot to add, also check your fuel line and make sure it's no where nears your exhaust as much as possible. It can cause the kind of hard hot start issues you're having.
    Last edited by 69cam; 12-13-2017 at 01:08 PM.

  5. #5

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    Again thanks, that all helps too. J.

  6. #6
    Join Date
    Nov 2014
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    Ont. Canada
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    Default

    Plugged air bleeds can cause the boosters to drip fuel. The air bleed is a siphon break at idle.

  7. #7

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    OK cool, I'll blast them through with air or solvent to make sure they're not plugged up. Thanks, J.

  8. #8

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    OK, first bit of progress. Both float needle heights were way too high, and the bowls had become pressurized I think. So fuel was seeping out the gaps and the vacuum nozzles were dripping. So I've fixed that though seeing where the fuel level in the bowl is, is really hard. I'm not sure if the air bleeds in the primary nozzles are blocked, because when I try and quirt WD40 through them, it doesn't seem to appear at the nozzles. Not sure how to clean these without damaging the bores. Maybe fishing line instead of wire. Any suggestions? Thanks, Jamie.

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