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Thread: Holley Sniper Ignition Timing

  1. #1

    Default Holley Sniper Ignition Timing

    Hi everyone. I have a '70 Cadillac Deville Convertible. With a newly overhauled 472 with stock camshaft. I have converted from Q-Jet to Holley Sniper, and it works just perfect.
    But I still have a question. I have a brand new original points distributor. So I just use the yellow cable from Sniper to the coil. I have set the idle engine timing
    to 7.5° and ported vacuum as the shop manual tells me to. So my question is, should I also set 7.5° idle timing in the Sniper EFI?

  2. #2
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    If this is not an ECU controlled timing application, ignore the EFI Base Timing Table (and anything ECU timing related).
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    Thanks for your answer Danny. It says 15° in my display on idle timing. So I'll just ignore this and continue to go with factory setting 7.5° degrees & ported vacuum?

  4. #4
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    Again, if this is not an ECU controlled timing application, ignore anything EFI timing related. You'll continue using the mechanical distributor.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

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    Then I'll stick to the factory setting. Thanks again Danny.

  6. #6
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    Yes, if the OEM factory timing specs work well for your engine. (I personally wouldn't run 7.5° of idle timing, especially with ported vacuum advance.)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. #7

    Default

    Thanks for your help and tips for my setup Danny. I really appreciate it. Can't find anyone else that has done this to a full-size Cadillac. So all help is appreciated.
    Originally, the 1970 Cadillac 472 engine has a solenoid that varies from ported vacuum to manifold vacuum to the distributor. This depending on engine coolant temp. I have removed this system and only running ported vacuum to the distributor. My manifold vacuum reads about 15-17 inHg at idle with 7.5°. I will try to use manifold vacuum to see how that works out. But right now, the Cadillac is being converted to in-tank fuel pump. I didn't like the external one. Too noisy. But when it's on wheels again I'll try manifold vacuum on distributor. Is there a some kind of ideal idle ignition time setting for the Sniper EFI?

  8. #8
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    Quote Originally Posted by Lars View Post
    I will try to use manifold vacuum to see how that works out.
    Vacuum advance should be connected to full manifold vacuum; not ported.
    8°-12° of vacuum advance is the typical limit (some canisters are adjustable).
    The (ported) timed spark port is only for emissions/EGR engines (LINK).

    Is there a some kind of ideal idle ignition time setting for the Sniper EFI?
    No, but there's an optimum amount of ignition timing advance, at idle for the engine.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  9. #9

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    OK. I'll set it on full manifold vacuum as soon as I get the fuel tank installed again. Thanks again for your help Danny.

  10. #10
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    You're welcome.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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