Announcement

Collapse
No announcement yet.

Timing issue, ping ping

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Timing issue, ping ping

    Iím in the process of tuning after the engine was rebuilt (390 V2) out of a 74 F100 I think. I have been fighting pinging issues starting at ~3/4throttle. To help minemize this I had set timing at idle with the vacuum advance connected to full intake vacuum, so I could have timing more retarded. I would set the timing at idle with VAC. Advanced at 12, this was giving me 38 at 3500 RPM, with vac connected. It would still ping but not so bad.

    Last weekend I pulled the Distributor appart and modified the advance cam stop to traduce the 26 (2x13) mechanical advance to 20 (2x10). Then, with vacuum advance disconnected I set initial timing at 12 (engine likes this) and confirmed that my max advance was 32. Leaving the vac. Advance disconnected I test drove it and still got pinging, but closer to full throttle. I went back home and set initial idle to 6 which gave me a total timing of 26 (with no vac advance). I went on another test drive and got no pinging, but it hasitated a bit off of idle.

    i donít see how it could be possible to connect the vac advance and not get pinging again. Does anybody have an idea why the engine starts to ping so early ( 26+).

    should I modefy the Distributor Cam so I only get only 14 mechanical advance so I can set initial timing to 12?

  • #2
    You didn't mention what octane fuel you are using. I find that anything under 91 octane will give me pinging regardless of how the timing is set. Using 91 octane and having the timing set to 8-10 degrees with the vacuum advance disconnected gives me adequate performance without any pinging.

    John
    John Pizzi - Squarebirds Administrator

    Thunderbird Registry #36223
    jopizz@verizon.net 856-779-9695

    http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

    Comment


    • #3
      Thatís a good point John, due to budget my daughter always filled it with 87, I will try something higher the next time I put fuel in it.

      Do you always run without the Vacuum Advance, what is the benefit of it?
      Last edited by SirBB; February 5th, 2019, 01:59 PM.

      Comment


      • #4
        I only disconnect the vacuum advance to set the timing, then reconnect it after it's set.

        John
        John Pizzi - Squarebirds Administrator

        Thunderbird Registry #36223
        jopizz@verizon.net 856-779-9695

        http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

        Comment

        Working...
        X