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Thread: 350 sbc breakup at 3000 rpm

  1. #1
    Join Date
    Apr 2018
    Posts
    2

    Default 350 sbc breakup at 3000 rpm

    I have a 350 sbc that starts up great and idles great just anything above 3000 rpm it starts to break up bad.
    It will do this in park.. and when cruising you will hear the little pops too just not as bad.

    New plugs gaped to .045 (RT45S)
    New MSD High vibration coil
    Ignition is MSD 6A with MSD billet distributor (New cap, rotor and mag pickup)
    Vacuum is steady 17 at idle
    New street avenger 670 with vacuum secondaries

    Engine is properly grounded both heads and intake.
    Wires from mag pick up routed away from any other wires and placed in plastic tube as well.
    MSD box directly to battery both + and ground.

    this is what it sounds like https://youtu.be/cqEEeeH5V8k

    Thanks for any help!

  2. #2

    Default

    Good description.

    What kind of "total" timing numbers are you getting?

    It kind of sounds like you might have the total in the 20's. When generally you should have a total at about 32 degrees BTDC.

  3. #3
    Join Date
    Apr 2018
    Posts
    2

    Default

    My timing was WAY OFF, as in the initial timing was around 20! I backed that down to 12 and the issue got ALOT better, still some pinging. Total advance is coming in too late, it was still climbing at 3.5K RPM. I order the spring kit to change the curve. I am also going to verify that my timing marks are correct and do the timing again! Hope this clears up the issue!

  4. #4
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    1,198

    Default

    That's a rev limiter.
    Have you got the 3000 chip in there?
    Last edited by Gaz64; 11-26-2018 at 11:46 PM.
    Regards, Gary

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