It's all in the timing.

Discussion in 'General Motoring' started by clay, Nov 2, 2009.

  1. clay

    clay Guest

    Finally got around to looking at the ignition timing after changing the
    timing belt a couple weeks back. ('83 245)
    12 BTD at idle, as it should be.
    Then the weirdness begins. Rev it up a little and timing retards to ~5
    BTD. Rev a little more, say 3500, and it creeps up to 15-18. Rap it and
    it appears to go up from there.
    So, what's up with the retardedness? Can't be good for performance.
    btw, I have the vacuum line on the knock generator plugged so the motor
    doesn't ping all the time... and, so it will pass smog.
     
    clay, Nov 2, 2009
    #1
  2. clay

    James Sweet Guest


    If I understand what you're saying, that sounds like it's working as
    expected. Remember that BTDC is *before* top dead center, so a bigger
    number means more advance and a smaller number is retarded towards TDC.
    It takes time for the fuel burn to take place, so the spark fires prior
    to the end of the compression stroke.
     
    James Sweet, Nov 2, 2009
    #2
  3. clay

    Boris Mohar Guest

    "Vacuum line on the knock generator plugged so the motor
    doesn't ping all the time." ?????



    Regards,

    Boris Mohar

    Got Knock? - see:
    Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

    void _-void-_ in the obvious place
     
    Boris Mohar, Nov 2, 2009
    #3
  4. clay

    Ken Phillips Guest

    I was puzzled about this as well; I thought the knock sensor
    (generator???) was essentially a microphone bolted into the engine
    block, sending an alternating electrical waveform of varying amplitude,
    dependant on whether the engine was 'knocking', so where does a vacuum
    line enter this equation.
    The only vacuum line I can think of on an average 240/245 engine of this
    age (apart from emissions control, or possibly carburettor control) is
    either going to the distributor (probably not in this case), or to the
    ignition management computer. This allows the computer or distributor to
    properly act upon the varying load and throttle positions, by altering
    the ignition timing; surely blocking this function would severely affect
    the cars performance?

    Best wishes,
    Ken Phillips
     
    Ken Phillips, Nov 2, 2009
    #4
  5. clay

    clay Guest

    Right.
    I understand about ignition advance curves, etc.
    That's why I said that the timing retarding initially can't be good for
    performance (or emissions...)
    Googling around for the correct name for the 'knock generator'... the
    Chrysler ignition control module, I found an explanation posted in this
    group back in 2002.
    Now to find the specifics of the recall to get rid of the retard, and
    figure out why I'm not getting more advance with higher rpms.
    Possibly because the motor has the Chrysler module but a Bosch
    distributer. As I understand it, the distributer cap should be white but
    it's a Bosch red one...
     
    clay, Nov 2, 2009
    #5
  6. clay

    clay Guest

    "Knock generator" = Chrysler ignition control module. A lame attempt to
    squeeze a little more performance out of an anemic four banger.
    See my reply to James.
     
    clay, Nov 2, 2009
    #6
  7. clay

    James Sweet Guest


    There was more than one Chrysler ignition system. Early K-jet cars used
    the one with the white distributor cap, later LH Jet 240s used a
    different system with a normal Bosch distributor. You should be able to
    retrofit in a later Bosch EZK ignition system if you want, although I
    haven't heard of too many problems with the stock ignition. You can
    install a hotter cam and higher flowing exhaust system to gain some
    power as well, although the biggest improvement is converting to a
    manual transmission if the car does not already have one. The old
    slushbox saps a lot of power.
     
    James Sweet, Nov 3, 2009
    #7
  8. clay

    clay Guest

    I didn't know they used a Bosch distributer with the Chrysler module.
    Thanks for that.
    It's a slushbox. Not looking to hotrod it. It's too tired for that. Just
    want to get the motor running like it's supposed to.
    Off to track down that vacuum delay valve.
     
    clay, Nov 3, 2009
    #8
  9. clay

    GlennK Guest

    I can send you the service information for the delay valves if you like
    just let me know where it is 15 pages
    Glenn K
    Volvo Certified Technician 2008
    ASE Certified Technician 2008
     
    GlennK, Nov 3, 2009
    #9
  10. clay

    clay Guest

    That would be great. Is it PDF or something could be sent email or paper
    copy?
    email is clayt
    and the domain is @pacbell
    not .com though, .net
    If it's paper, would FAX be easy? Snail mail is a pita. Stamps,
    envelopes, and all...

    Not much about it on Google or in my anemic Haynes manual.

    Thanks!
     
    clay, Nov 4, 2009
    #10
  11. clay

    clay Guest

    Got it, thanks!
     
    clay, Nov 5, 2009
    #11
  12. Is your main pulley floating on its rubber the harmonic balancer gives up
    ant the timing goes accordingly ?.
     
    Jon Robertson, Dec 1, 2009
    #12
  13. clay

    clay Guest

    No rubber on the front pulley. Straight steel.
     
    clay, Dec 1, 2009
    #13
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