Any ideas what this Cause of hurt bearings? Pics inside.

Discussion in ' Tech Questions' started by gmhpwr, Aug 10, 2018.

  1. rb0804

    rb0804 Member

    Aug 7, 2010
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    What was your total advance at idle and head temp with retarded timing vs total advance at and head temp with more advanced timing?

    I was taking you post like you were referring to EGTs, with a lot of timing pulled the egts can be 1300-1400, but when you crank some timing in they ‘cool’ off a bit to 900-1200, even though nothing is really cooling off. With the retarded timing the a/f mixture is burning going out the pipe resulting in a false, high reading. All the while the plugs still look brand new. Advance the timing a tad and the heat stays in the chamber where it belongs, the egts drop but the plugs are starting to show some heat. Egts are good for diagnostic purposes but I wouldn’t really rely on them to balance cylinders and put faith in them for how much to lean it. Just a side note, EGTs vary if they come in from the top or the bottom and vary depending on how far they are in the pipe and how far away from the cylinder they are.
  2. td3829mk

    td3829mk Member

    Dec 31, 2015
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    In a sense. But I was mainly referring to idle and keeping head temp manageable before even launching the car. With retarded timing and high EGTs at idle it put way too much heat in the motor (around 200 head temp), ran like crap down the track, burned the cad off the plugs, made them appear to be extremely lean and showed signs of detonation. Running total timing at idle along with cooling the EGTs down to around 450-500, head temp stayed around 150 and the car ran much better and the plugs looked new. I trust plug reading more than anything but I also use EGT's as a reference, since I have been in the unfortunate position of knowing what my combo's limits are.

    What I was getting at in my original question was, if you are running a head (like a fuel head) that works best with a 36 degree lead (or whatever it is for those), wouldn't you want to run it closer to that number to keep everything in check? Like I said, I have had bad things happen with high head temps so trying to avoid that tends to make sense to me.

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