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Thread: Sick of my mechanic, DYI HyperSpark?

  1. #21

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    If you're not using it, I'd like to buy it from you. Andrew

  2. #22
    Join Date
    May 2014
    Location
    Bostwick, GA
    Posts
    339

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    Quote Originally Posted by jpalmer1717 View Post
    There are FIVE lines and a ground wire coming from the top back side of the gas tank. I don't know if any of these are a vent. But I will try the loosening of the cap idea.
    Track them down, and let us know.

  3. #23

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    Took a 20 mile ride last night with the gas cap loose. It ran so bad I thought for sure it was going to quit on me. Just a lack of HP. A dog. And with a slight engine vibration. As soon as I hit 60 MPH the horsepower kicked back in and the engine smoothed right out. In & out. In & out. Sometimes I'd lose more power than other times. I live in the mountains and climbing narrow roads with steep hills with little power is stressful enough, let alone owning my first classic car that no one can fix. I ordered the HyperSpark out of desperation at this point. I'd also like to try an upgraded fuel pump if HyperSpark doesn't work. This really sucks.
    Last edited by jpalmer1717; 04-19-2021 at 09:51 AM.

  4. #24

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    It sounds like you might have some wiring issues or RFI interference. Andrew

  5. #25

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    I ordered new plug wires to go along with the new plugs recently installed. Any specific other wiring I could check?

  6. #26
    Join Date
    Oct 2020
    Location
    Ontario, Canada
    Posts
    74

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    Quote Originally Posted by jpalmer1717 View Post
    I ordered new plug wires to go along with the new plugs recently installed. Any specific other wiring I could check?
    "Chuck L" pointed out that some of your Sniper wires are coiled and tie-wrapped together right beside the HEI distributor. The plug wires appear to be in contact with that loop. You need to route all Sniper wiring away from the HEI !!!

    Ford 302 installations really suffer from having the distributor close to the front mounted Sniper ECU. ECU resets prevent proper operation.

    Are your new plugs resistor type? Early HEI specified very large plug gaps for the lean fuel mixtures in the 1970's. The gaps were later reduced to 0.045-inch. Excessive gap would challenge your wires' insulation. The richer Sniper mixture is likely OK with 0.035-inch plug gap.

    Any Radio Frequency Interference (RFI) is a problem for the Sniper ECU. Read this LINK

    "AndyF" pointed out that your engine temp seems low. If you run a 160-degree thermostat you will likely have self-tuning problems, 180-degree minimum.
    Last edited by Candu SNO; 04-19-2021 at 11:35 AM.

  7. #27

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    Just want to add a quick note. I went for a short spin today so I could record a new datalog (forgot to stop the recording before shutting down so it didn't save...grrr). But throughout this drive I was getting some sort of backfiring/popping that sounded like it was coming from the engine. The problem is definitely getting worse quick. It ran rough the entire drive and was lacking about 150 horsepower.

  8. #28
    Join Date
    May 2014
    Location
    Bostwick, GA
    Posts
    339

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    Post #22, where do all those lines go?

  9. #29
    Join Date
    Oct 2020
    Location
    Ontario, Canada
    Posts
    74

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    Here's a sketch from this Chevelles Forum posting regarding 1972 GM A-Body fuel tank venting:
    Click image for larger version. 

Name:	72 GM fuel tank venting.jpg 
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    The box behind the back seat is vented via the Charcoal Cannister. There's also a vapor return line from the fuel pump. The Charcoal Cannister is frequently removed as emissions "junk". Since we don't know how this sytem has been modified for the electric fuel pump, some mysteries remain.
    Last edited by Candu SNO; 04-19-2021 at 02:34 PM.

  10. #30

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    Quote Originally Posted by jpalmer1717 View Post
    I ordered new plug wires to go along with the new plugs recently installed. Any specific other wiring I could check?
    I suggest you read this:
    https://forums.holley.com/showthread...ey-EFI-systems. Andrew

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