Is my car running what it should? Engine build thoughts?

Discussion in 'High Performance Modifications' started by Jhboy10, Sep 14, 2020.

  1. Scaleytail

    Scaleytail Veteran Member

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    What’s next??
     
  2. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    Next step is adjusting the timing curve, which is how the spark advance acts at higher RPM. This is done with a series of springs and weights inside the distributor. Setting the spark plug gap is also done.

    From there (or best at the same time) hooking the car up to a wide band O2 sensor and adjusting the off idle mixture on the carb. This involves swapping jets metering rods and power valves (depending on the carb).

    There are ways to do this without a chassis dyno, but they aren’t as accurate or as definitive.

    on an EFI car this is all done from a laptop, but our old analog cars need a little more tinkering
     
    Last edited: Sep 15, 2020
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  3. Jhboy10

    Jhboy10 New Member

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    Thank you, I was gonna ask what steps to take as it is unlikely the car will see a dyno. An aluminum intake has been on my mind for a while now, been trying to pick the best one that'll fit under a stock hood.
     
  4. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    Not everyone has access to a Dyno - there's other tools to use.
    First of all, the Performer RPM intake manifold should clear your hood no problem assuming you are running a drop base air cleaner. It's going to save you weight, and help bleed of heat from the intake charge, which is always good. I'd install a valley pan at the same time to help keep out oil off the underside of the intake manifold.

    For tuning the carb, a lot can be learned by reading the spark plugs. I would recommend pulling one of the plugs, and posting a picture up here in a separate thread titled something like "help me read these plugs". I'm partially colorblind, so personally useless for this, but there are a few guys on here that are masters.

    What are you running for a distributor?
    This is an excellent article on how to go about setting your ignition advance:
    https://www.hotrod.com/articles/set-ignition-curves-create-optimal-performance/
    Believe me, when I say, the ignition curve is half the battle. One of the biggest advantages modern cars have in the power and fuel economy dept is the ability to adjust the timing, quickly and in real-time.

    A good general baseline for timing:
    Initial 4-deg BTDC,
    32 deg total timing, all in at 2500RPM
    Every car is different, but this is a solid baseline for a streetcar.
     
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  5. Jhboy10

    Jhboy10 New Member

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    I'm running Hei with a Summit upgrade kit on it. I have played with the timing curve some right now it's set about 14 at idle and 38 or so by 3000.
     
  6. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    IMHO, Way too much timing. Pull that back to 8 BTDC and I bet the whole car runs better.
     
  7. Z28zz383

    Z28zz383 Veteran Member

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    I am def no expert next to the guys giving lots of good info on here. But, I would add that SOMETIMES a little tire spin will get the car into the power band quicker. If you can experiment with some harder compound tires or smaller dia. tires there might be an improvement. Drags are very soft and sticky. Tall, sticky tires are hard to get moving w/o a lot of tq. JM2cts
     
  8. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    I ran the RPM Air Gap for several years, stock hood, Eddy drop base cleaner. It was tight, but it fit, even with a N2O plate. No need for galley pan with air gap. I did put a Dremel to a couple of hood scoop bolts. Agree with the rest on getting your timing curve set, there's a whole lot to be gained there.

    If you can swing it, and want to go this way, the Eddy ProFlo 4 will make that a whole new engine. No more fiddling with a carburetor or distributor, all done with a touch of the screen.
     
  9. 1980RS

    1980RS Veteran Member

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    I looked at my Performer Air Gap sitting on the shelf, it's lower than the Rpm Air Gap so that one might work out for you.
     
  10. Jhboy10

    Jhboy10 New Member

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    My plugs look like they're possibly lean, if I stepped up the jet size then made a pass to see if it helped should I change both sides or just secondaries?
     

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