Good all around timing & afr table?

Discussion in 'High Tech Retrofits' started by 73 Z, May 4, 2019.

  1. 73 Z

    73 Z Veteran Member Gold Member

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    I have a Sniper TBI & dist. on a sbc 383, 9.4 comp, 227@.050, 530 lift, .373 rear, m21/cr, for street use. Timing & AFR can be infinitely programmed per rpm, map/kpa
    On my 2nd tune still have loss of pull at any type of stomp throttle situation, like a low pump shot, but that has been increased. Its sounds & feels like its popping out exhaust when it happens. Not a backfire more of a base tone (quiet exhaust), but not as bad if I ease throttle.

    17 start/static, 38 cruise, 36 wot. AFR 13.3 cruise, 12.2 wot.
     
    Last edited: May 26, 2019
  2. 8pack

    8pack Veteran Member Lifetime Gold Member

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    I have a vey similar set up to you. I also had that same popping out the exhaust sound. I had some help in remapping my fuel and timing. PM me and I will email you my tune sometime this week. My Timing is controlled by the sniper.

    Mine runs pretty darn good right now. It is probably tuned more for dirveability than all out power but I am really happy for now.
     
  3. K1ng0011

    K1ng0011 Veteran Member

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    Sounds like you might need AE (acceleration enrichment). You can check your AFR as soon as you hit the pedal to accelerate if it's lean you may need more AE. As for timing on an old sbc you want around 36 degrees total timing with older cylinder heads. If you have the sniper controlling the timing I would verify it actually is controlling it.
     
  4. 73 Z

    73 Z Veteran Member Gold Member

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    Timing is controlled finally, this time I verified with light and locked a setting in the ecu then revved up and it held the setting so I should be good.
    This might have been the problem. Also my 1st/2nd tune I wasn't understanding the MAP/KPA timing and fuel table vs rpm/throttle opening.
    Made a 3rd tune, but haven't loaded yet! I might increase the timing values.
    The grief I gave myself is I never tuned it properly when I had the carb and msd dist, it did the same thing then to.

    Thanks for the replies
     

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  5. 73 Z

    73 Z Veteran Member Gold Member

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    Well the 3rd tune woke it up, but now its popping out TBI when I start from a stop and wants to stall. so maybe to lean or timing?
    8pack how do I pm I don't see a link
     
  6. 8pack

    8pack Veteran Member Lifetime Gold Member

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    I got rid of the progressive secondary linkage as that was also causing some issues......
     
  7. 73 Z

    73 Z Veteran Member Gold Member

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    Thanks for the tune, haven't tried yet been raining. I'm going to revert back to 1:1 and try it!
    how do you determine the reference angle? all base cals show 45.0 you have 57.5
     
  8. 8pack

    8pack Veteran Member Lifetime Gold Member

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    If you are using the Hyperspark distributor that is the setting. I can't explain why. Has something to do with the way the rotor is phased. Page 5 of HS distributor install manual gives you those settings.

    I forgot about the website below. Read everything he has in is blogs about set up etc. Tons if good info. In this link scroll down to Hyperspark and read. The article gives you the reference angle settings for all the different distributor options including the HS (57.5*), the Dual sync (50*) and the MSD (45*).

    https://www.efisystempro.com/efi-sy...ying-holley-terminator-sniper-ignition-wiring

    All the sniper install articles:

    https://www.efisystempro.com/efi-pro-hangout/holley-sniper-efi-instruction

    I think there is more if you dig around. That site was invaluable in getting my set up right.
     
    Last edited: May 27, 2019
  9. 8pack

    8pack Veteran Member Lifetime Gold Member

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  10. 8pack

    8pack Veteran Member Lifetime Gold Member

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    This is also very informative and gives a good visual reference of the different areas that are impacted in the table.

    Sniper Fuel table sectors.png
     

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