Results 1 to 2 of 2

Thread: MC-4 retard trigger?

  1. #1
    bikerphil Guest

    Default MC-4 retard trigger?

    Hi there,

    I'm setting up my MC4 to use the 3rd stage of retard on a time based ramp. As i want it to pull timing out as the nitrous % progresses.
    In the manual it says the following:
    The start point for the progressive retard can be activated by
    the release of the launch rev limiter, by rpm or by a separate external activation wire that can be connected to a timer or other devices.

    However it doesn't say how you choose which will activate it? or is it all or any of those things? I was hoping it would start off the launch limiter.


  2. #2


    There are a few ways to use step 3 of our retard features. One way is by setting the rpm to the lowest value of 800 rpm being most motorcycle engine will idle above this value. Then setting the ramp time and retard amount once 12 volts are applied to the tan wire the third step will be active and start retarding according to how you have it programmed. The second way is by using the RPM value to activate the retard. By entering an rpm value, ramp time, retard amount then applying 12 volts to the tan wire the third set is active but will not start removing timing until the rpm value is reached. When12 volts are applied to the dark blue launch limiter wire the MC4 is reset to zero and ready. If you have any question please give me a call.

    Thank you


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us