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Thread: Setting up Rev Limiters using timing control.

  1. #1

    Default Setting up Rev Limiters using timing control.

    OK, so after a few hours of trial & error, I finally got the timing control working with my MSD distributor, seemly without any RFI issues.
    Now I'm trying to set the rev limiters and learn how they're controlled. Keep in mind, I'm coming from using a MSD 6AL-2 Programmable box and that has more limiter features than I'll ever use. The limiters I used with the MSD box were RevMax, RevBurn (burn-out limiter) & staging RevLaunch. The RevMax limiter is self explanatory, the RevBurn I had connected to my brake light switch and the staging RevLaunch limiter I had connected to my clutch on/off switch.
    So, what is the Sniper capable of providing and how do I get them activated? Maybe it's just me, but I can't find much info on it. I go Advanced-->Launch-->2-Step, and I'm not quite sure what I'm looking at, How do I set the Max rev limiter? How do I set the RevBurn & 2-Step limiters? What wires do I use? Are they ground or power activated circuits?
    Can someone please be very specific with this, as I'm obviously not understanding this at all. I feel like the MSD instructions are much more clear on this subject. Also, what does the Launch Retard feature do and how is that beneficial?

  2. #2
    Join Date
    Dec 2009
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    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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    Rev Limiters Main Over-Rev.
    Description: The ECU will cut spark at any RPM above the “High RPM” setting Rev Limiter #1.
    Description: This is generally used as a two-step and must be wired to an ECU input.

    This much I know...not much help. I'm just using the handheld by the way. I figured out
    the max rev limiter. Does it not have a RevBurn feature? I'm still unclear on the wiring.

  4. #4
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    Dec 2009
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    Connecticut
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    18,698

    Default

    Quote Originally Posted by venomous121 View Post
    I'm just using the handheld by the way.
    Use the Sniper EFI software, it's much more intuitive.
    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

    Default

    I'll have to buy the cable then. I figured out that the input is a ground switch. I set the 2-Step to input #1. When the input is grounded, the RPM raises and timing shoots up without touch the gas pedal. Then if I activate the 2-Step, then depress the accelerator, hit the limiter, and then let off, the RPM hangs high and the timing is reading 44° (normally 15° at idle). I have to hit the accelerator a couple of times to get it to come back down. Is this something in the programming, and one of the reasons why you're telling me to use the EFI software?

  6. #6
    Join Date
    Oct 2016
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    Albuquerque, NM
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    Default

    Quote Originally Posted by venomous121 View Post
    OK, so after a few hours of trial & error, I finally got the timing control working with my MSD distributor, seemly without any RFI issues.
    Any tips on getting it to work correctly? Did you use the stock rotor or the adjustable rotor? Thanks.

  7. #7

    Default

    Quote Originally Posted by bryaneh View Post
    Any tips on getting it to work correctly? Did you use the stock rotor or the adjustable rotor? Thanks.
    As far the RFI, to get rid of that, in a nut shell, I swapped over the contact from the old stock MSD rotor to the adjustable one and bent the tip at a 45° angle to match the installed height of the stock MSD rotor contact in relationship to the cap towers. For just getting the MSD distributor to work, I set the engine at 15° BTDC, set the distributor in straight up (didn't worry turning the rotor to -15°, since my rotor doesn't have that feature), and started it up. I set static timing with the Sniper at about four different degrees, I.E., 10°, 20°, 30°, 40°, etc., and set the my distributor with the timing light to verify it was correct. I haven't driven it yet though to verify that the RFI is gone completely. But seems OK in my driveway.

  8. #8
    Join Date
    Sep 2015
    Location
    Palm Bay, FL
    Posts
    162

    Default

    Quote Originally Posted by venomous121 View Post
    Can someone please be very specific with this, as I'm obviously not understanding this at all. I feel like the MSD instructions are much more clear on this subject. Also, what does the Launch Retard feature do and how is that beneficial?
    I do agree that this is probably going to be easier to setup with the Sniper EFI software, and since your cable is on the way I'll reference those steps. Please forgive any ignorance I may display regarding drag racing. My racing habit is much more in the road/circle track world. I post this as something to launch the conversation as I didn't see anyone running with it.

    In the Sniper EFI software, you go to the Spark ICF (click on the spark plug icon on the tool bar) and then click on "Rev Limiters". There you will see that you can set up a main over-rev limit (where you set your redline) as well as a triggered rev limiter (Rev Limiter #1), where you can set a lower, triggered rev limiter for a staging rev limiter or transbrake rev limiter.

    When you enable triggered rev limiter, you will see that it requires an input. It is "unassigned" by default and has only one choice (assuming you've not assigned it to something else): Input #2.

    Since you like to know the whys behind the how, click on "Pin Map". This gives a map of all of the available input and output lines. As you see, there are two inputs and 3 outputs available on the Sniper. Only one of the two inputs are assigned by default: A/C IAC Kick. Input pin #2 (which is wired to your yellow wire on the 10-pin connector) is "Unassigned" by default. But when you go into the Rev Limiter section (as described above) and select "Input #2" the Pin Map will show that this pin is now assigned as "Spark Rev Limiter #1".

    So, going back to the Spark > Rev Limiter > Rev Limiter #1, you just click enable, select Input #2, and set the rev limit where you want it. Then, you put a momentary switch to ground on the yellow wire on the 10-pin connector. Stage, press switch, WOT, release on green.

    In addition to a triggered rev limiter, you can also set a launch retard. In the same Spark ICF you will find "Launch Retard", which, when enabled, allows you to trigger a set timing retard, activated either by the triggered input or by the release of the triggered input. Note that this allows you to select the same input #2 (although I'm getting way outside my expertise to say if that is a good idea.)

    Note that if you're not using the A/C IAC Kick you can go into the System ICF, Basic I/O, change the A/C IAC Kick input to "Unassigned" and you ave a second input you can use.
    Chris Myer
    800-880-0960 x654
    chris@EFISystemPro.com

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    all Holley items, including the full line of Holley HyperSpark Distributors!

  9. #9

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    I used the Input #1. I never went in & unassigned it from the A/C IAC Kick. Maybe this is why my timing jumps as well as the RPM when I switch the circuit to ground. But I did all of this from the handheld. I'll try it again when my cable comes in.

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