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7.3 timing and egt???

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Clb, May 15, 2019.

  1. Clb

    Clb Another old truck Supporting Member

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    Ok I could use some tech from the timing guru's
    Pulling long hills on i5 at 6k altitude and I have to drive by pyro (never had an issue) need to fix this b.s. pdq.

    Timing was at 9.5 and the 93 in sig line would stay under 1100 at 11-12# boost.
    Bumped it back to about 8.7 or so...
    Now the egt's rocket up when the effin faccett pusses out (dash light on)
    I noticed about 200 more cruize egts at the 8. Versus the 9.
    Is this like a gasser when retarded it runs hotter?
    If I advance it back to 9.5 will it run cooler?
    If I back outta the fuel to get the pressure up it Sheds some boost, and drops the egt quick, no shit huh?!
    I would appreciate any advice....
     
  2. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    The facet cant keep up, and the rule of thumb from testing Mel did is 1* of advance is lost for every 2 psi of inlet fuel pressure lost. (IIRC!)

    So if your facet is around 6-7psi during the unloaded timing setup at 2k rpms, but the IP is drawing vacuum at WOT under heavy load then you're losing at least 3* of timing and I am starting to think it's even more than that.

    So like me it sounds like you have to find that middle place where you're not too advanced at low RPM but you dont run out of timing up high.

    If it was happier at 9.5 absolutely bump it back up there.

    And yes every engine runs hotter with retarded timing, but 8.5 *should* be good for these engines. Even 6.5 is often a good spot for the turbos but because of the facet, there is a whole nuther can of timing worms involved...hope that helps, I'm not a guru. ;)
     
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  3. Clb

    Clb Another old truck Supporting Member

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    Thanx, I Read mels disirtation ...

    Faucett is NOT keeping up.
    Triggers the light at 3k easy, 2800 often.

    6k on the pin, new fuel filter 2 full tanks both lit the light.
    I feel the e pump was a mistake personally.
    It can stay in service untill it really pisses me off.
    I just want the egt's down.
     
  4. Booyah45828

    Booyah45828 Full Access Member

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    Retarded timing will give a hotter exhaust.

    I'd fix the fuel supply issue before I'd start playing with the timing. Until you can get a predictable and consistent fuel pressure, it's anybody's guess as to what your timing is doing.
     
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  5. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    I agree I think your egt issue is related to fuel pressure not any setting on the ip
     
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  6. Clb

    Clb Another old truck Supporting Member

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    Yep the search function gremlins sold me on the faccet years back...now I need to find a holley on 101 thru oregun...
    Disclaimer...
    I have pulled preist's grade hwy 120 into yosemite pinned never an issue...same pump and timing-Lame




    it pulled cooler at 9.5 so in the am I'm tuning back to the old setting.

    Fubar that 1 deg. Makes this much issue.
     
  7. Macrobb

    Macrobb Full Access Member

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    Just put the darn mechanical pump back! Add a booster pump if you need, but the good old mechanical pumps have no trouble putting out a consistent pressure(within 2 psi idle to WOT) and plenty of flow at WOT!
     
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  8. Clb

    Clb Another old truck Supporting Member

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    Yep, I left the phawker at home.
    Anyone recall if the e pump will flow thru a mech. Pump if plumbed in series??
    Or does it cause issues?
     
  9. gandalf

    gandalf Senior Member

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    Yes, I'm pretty sure the e-pump will flow through the stock lift pump. That being said, I would not set things up that way. I'd avoid it like the plague. IF, for whatever reason the lift pump diaphragm breaks you will fill the crankcase with diesel fuel because the e-pump will keep the fuel flowing. When the fuel hits the ruptured diaphragm much of it will follow the path of least resistance, into the crankcase. You would probably be very unhappy with the result.
     
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  10. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    It will cause issues, it likes to rupture the diaphragm and fill the crankcase with fuel. I believe O’Reilly can get the Holley pumps, most hot rod shops carry them
     
  11. Clb

    Clb Another old truck Supporting Member

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    thanx ken great observations...
    thanx wes for all you put out here as to tech resource.
    Joshthebear pointed out to tee in the epump after the mech. And set a check valve in between...

    whoohoo options...
     
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  12. Booyah45828

    Booyah45828 Full Access Member

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    Couldn't you run the e pump inline after the mechanical? I would think it would feed enough volume that way. Does any body know how the e pump regulates pressure? I don't think you'll have too much pressure this way but check to be sure. I believe you still should be able to draw fuel through the mechanical pump in order to prime filters. You'll still have to run the e pump while running like you do now.
     
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  13. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    I’ve got pumps here i could overnight to you if you get in a pickle.
     
  14. Clb

    Clb Another old truck Supporting Member

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    I will keep that in mind bud.
    I reset the timming back to 9.5, gunna make a pull up the Oregon coast and see how it reacts.
    Pm incoming.
     
  15. Clb

    Clb Another old truck Supporting Member

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    Oh yea...
    Big difference, albeit without altitude.
    Think I am good fer now.
    Still gunna toss the faucet delta price phister crap when i git home.
     

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