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confused over ignition timing

Discussion in '206/246' started by bertspeed, Jul 4, 2014.

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  1. bertspeed

    bertspeed Formula Junior

    Sep 19, 2009
    302
    #1 bertspeed, Jul 4, 2014
    Last edited: Jul 4, 2014
    I am trying to set the ignition timing on a 2.0 fiat dino engine but am finding different answers.My manual shows identical advance curves as in corbanis saga 060625,but it shows static at 10%,whereas corbani says 6%.Ive been told by superformance and 24Hundred to only set timing in static and not stroboscopic mode for all dino engines.further more I cant get it to this setting even with the adjustment at max on the bottom of the distributer. Any advice appreciated.
     
  2. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
    Full Name:
    Tony
    The reason why you do not use a strobe to set static timing is that you have no idea if the centrifugal weights are applying and mechanical advance (MA) while the engine is running. If I remember correctly you should not get any MA below 1000rpm. Unless you have fully rebuilt the dizzy and tested the entire MA range then you have no idea if it is applying a advance.

    The drive dog and adjustment on the dizzy body is more than sufficient to fine tune the timing so you have done something wrong. Check the cam timing is aligned with the marks on the camshafts and end caps at TDC (PMS mark on pointer which stands for Punto morto superiore ie top dead center) number 3 cylinder.

    The rotor arm should be set at approx. 4'O clock aligned with the mark on the casing and rotor arm.

    Ensure the points gap is correct. Set the engine to 6 deg, connect a test lamp across the points or coil (neg terminal to earth)and rotate dizzy until the test lamp JUST lights up (points open). Lock the dizzy at this.

    Check MA with a strobe at 5500 rpm is 35 degree's.

    If its not then you need to adjust the weights which you will need specialist help unless you have a Sun machine tucked away somewhere.

    Tony
     
  3. bertspeed

    bertspeed Formula Junior

    Sep 19, 2009
    302
    Thanks for the reply Tony.The cam timing is spot on and Ive set the points to 13/14 thou.I get quite a bit of advance as the engine is revved up,but I cant get the timing to zero at idle.I will double check the drive dog and adjustment and get a helper to confirm various timing points up to 5500 rpm.
     
  4. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
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    Tony
    I don't understand what you mean by zero, but if you cannot see aprox 6 deg on the strobe at idle then your mechanical advance weights need adjusting, especially if you cannot get total advance of 35 deg @ 5500

    At about 900rpm you should not get any advance applied but as explained above you possibly are. If your strobe has an advance built in then you can measure very crudely what is happening. My guess is you are getting about 8 deg at idle plus static. Basically the MM dizzy was crap when new and ******* useless when 40 years old.

    Try rotating the rotating the dizzy very slightly with the engine running and note any increase in revs, we get fixated on following specific graphs but that sometimes does not equate to what the engine actually wants.
     
  5. alhbln

    alhbln Formula 3
    Consultant Owner

    Mar 4, 2008
    1,749
    Berlin, Germany
    Full Name:
    Adrian
    #5 alhbln, Jul 6, 2014
    Last edited by a moderator: Sep 7, 2017
    As Tony said, at idle (850-900 RPM) the dist won't add any advance if it is in proper condition. I usually set the static advance in situ with a timing light when i know the dist is ok (otherwise i'll test the dist on the distributor tester first to make sure everything is in order).

    Static advance should be set to 10º to reach a maximum of 39º-40º advance, see chart below. 6º is very conservative and with the (in EU) available 95 ROZ fuel you'll want to have 10º advance to get at least 20º at the crank shaft to have some torque at lower RPMs.
    Image Unavailable, Please Login
     
  6. bertspeed

    bertspeed Formula Junior

    Sep 19, 2009
    302
    Finally got the static timing set but not the automatic advance so I had to pull the distributor off.I found each of the two short springs for the advance weights 14mm long and the two long ones 16.5mm and 18mm each.Does anyone know what the correct lengths should be and where to buy just the springs.
     
  7. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,811
    Norfolk - UK
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    Tony
    Word of warning, setting the advance curve is not possible without access to a specialist machine. Take it to someone who can do this for you.
     
  8. alhbln

    alhbln Formula 3
    Consultant Owner

    Mar 4, 2008
    1,749
    Berlin, Germany
    Full Name:
    Adrian
  9. bertspeed

    bertspeed Formula Junior

    Sep 19, 2009
    302
  10. rosso corsa motorsport

    rosso corsa motorsport Formula Junior

    Nov 30, 2008
    268

    the best you can do is not play with it yourself if you don't know this distributor remove distributor send it to someone having the right knowledge and parts to set advance curve just as adrian explain +-1 degree then have it fitted back to engine and set to 10 degree with strobe lamp, that will give you a total of 40 degree that wil make your car run like hell.
    how long the springs need to be depends on what type of weights you have
    you also need to check springwire thickness
     

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