Timing curve for a 340 4bbl with Holley Hyper spark & Sniper EFI

Discussion in 'High Tech for Old Iron' started by CanadianBird, Jun 7, 2021 at 11:22 AM.

  1. CanadianBird

    CanadianBird Silver Level contributor

    Any recommendations? Fighting spark knock while stepping into when cruising at 45 mph.

    wot 30
    Cruise at 36
    Initial at 15
  2. Max Damage

    Max Damage I'm Working on it!

    Approximately what is the RPM of the engine at 45 MPH? So many variables, fuel supply, timing, temperature...

    Make sure you are using good gasoline. This is step 1.
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Not enough octane. Not sure what your ACTUAL static compression is, but that cam may have enough dynamic compression to put you close to RACE gas territory.
    Last edited: Jun 7, 2021 at 5:58 PM
  4. Jim Nichols

    Jim Nichols Well-Known Member

    I used that cam in a 215. A little too much there, but was just right in a Rover 4.0. I'd use the 50234 in the 340. We used the 50233 in a 300 stroker. It was pretty mild in that. You need lower Dynamic compression. There is 4 degree advance built in the cam. Try retarding it 4 degrees.

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