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Thread: Street Avenger 570 Throttle Issue

  1. #1

    Default Street Avenger 570 Throttle Issue

    I have a Street Avenger 570 carburetor on a fairly stock 302. The issue I'm having is that I get the best acceleration at around 2/3 throttle. If if go to wide open throttle, the car slows down. I was wondering what this might indicate, and what I should look into? The carburetor was put on out of the box and turned by a professional 12 years ago. Very little has been done to it since. Sorry, I'm very much a novice with carburetors. I did a lot of reading, and I'm not finding anything that describes this problem.

  2. #2
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    Sounds like you should have the carb pulled down, acid soaked, and reassembled. Probably has some blockages within the primary and/or secondary main jet fuel circuits. Gary
    Regards, Gary

  3. #3

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    Do you think rebuilding the fuel bowls and metering block would likely be good enough? This will be my first time doing this sort of work on a Holley carburetor, and the full job intimidates me. Also, I think it has a 6.5 power valve in it. The vacuum is always around 16. Would it be worth it to go to a 7.5 power valve?

  4. #4
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    I'd start with the primary side.
    Remove the bowl and metering block.
    You may see obvious issues upon removal.
    If you do see corrosion, etc., from water, remove the secondary bowl as well.
    I don't see any benefit changing to a 7.5 or even 8.5 PV, since you issue is 2/3 onwards.
    With engine OFF, open the throttle, and operate the vacuum secondary throttle by hand, you should feel nice smooth operation and hear the air from the vacuum chamber within the venturi area. Gary
    Regards, Gary

  5. #5

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    OK. I have a rebuild kit on order.

  6. #6

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    I went ahead and took off the primary fuel bowl and metering block, and they seemed fairly clean inside. I soaked them in carburetor cleaner, and replaced the gaskets along with the accelerator pump diaphragm and fuel inlet filter. The secondaries appear to be operating properly as far as I can tell. I put it all back together and the car drives the same as before.

  7. #7
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    I'd say you need to perform a fuel flow test into a container.
    You could have a bad pump, pickup screen or partly blocked fuel filter. Gary

  8. #8

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    I replaced the inline fuel filter. The old one had some chunks of rust like material in it, so I could imagine the pick screen could be partly blocked. Would an inline fuel pressure gauge be adequate in helping with a diagnosis?

  9. #9
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    Your fuel tank is rusted. The pickup screen will be blocked. The fuel filter has done its job, and was the last restriction to fuel flow, hence the power loss.
    I'd say pull your fuel tank out, send it out for a clean-out and inspection. Replace pickup screen, flush out lines, pump etc. A carburetor is not always the first reason for low power. Gary
    Last edited by Gaz64; 08-07-2020 at 05:43 PM.

  10. #10

    Default

    In the late '90s, when I was reviving the car and getting it up & running, the gas tank was taken out and treated and sealed. I guess it's about time for the seal fail.

    I'm going to go with a new gas tank with all the necessary parts. I see an option for a larger 19 gallon tank. This is going to be more of a project than I expected. Adding a pressure regulator as well shouldn't hurt the situation.

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