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Retard timing to 0 degrees at idle?-gctid390547

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    Retard timing to 0 degrees at idle?-gctid390547

    (Recently sold to client) Was pinging real bad at 3000 rpm's coming out of the hole,

    (90 model 5.7L, Thunderbird IV, fresh rebuild everything)

    Had timing at spec, 8 degree idle, verified advance curve, by the book.

    Had to retard the timming to 0 degrees at idle to make pinging all but gone. Slight random ping at 4k.

    However, temp still climbing to 200 at that high of RPM. (NEW half closed cooling system SeaKamp with 160 degree stat)

    Seems to have good flow but (NEW Aluminum) risers and mans are getting hot. Verified with IR temp gun.

    I haven't gotten around to do the clear hose test, although I have the hose!

    Some restriction somewhere.

    Scheduled to replace impeller (again) this week. I'm off to Vegas for a trade show this week (Real day job)

    So I am going to let my shop buddies replace the impeller while I'm gone.

    More to come......

    #2
    Jim, any signs of a lean fuel/air ratio?

    Are the spark plugs the correct heat range?

    Are the TDC marks accurate? (iow, has the outer ring of the harmonic balancer slipped by chance?)

    At 0 degress BASE, this engine will not like idle speeds very well.

    The progressive and TA will also be held back, and you will see performance suffer.

    How did you check to see if the module was presenting the correct advance curve? Just curious.

    .
    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

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      #3
      Yes to most all of the above. This is the engine you and I spoke of a couple of weeks ago when I blew a head gasket due to detonation.

      I'm leaning (no pun intended) on the damper mark or even amybe off a tooth on the timing.

      Plugs are MR43T's.

      Starts cold and idle's extremly well at 0-degrees base timing.

      Carb is still dribbling fuel at idle so I'm thinking it's not running lean. (maybe if the carb is dribbling fuel at idle it may be running lean at 3k + rpm?)

      Thunderbird IV module is working perfectly. Curve is right in spec.

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