News

SOLVING LOW IDLE

Discussion in '308/328' started by absostone, Jul 28, 2019.

  1. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Ok now I set the idle to around 950 and I have any where from 3.5 KG to just under 5KG at the highest. Took it for a ride without the air filter. Runs good but idles low sometimes down to 750-800. Too much under hood hot air?
     
  2. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,470
    Texas
    Full Name:
    Steve Magnusson
    Can't call that "good". You must still have some cylinder(s) not running at idle (and there should be no reason that you can't better match the airflows). If you turn each idle screw closed one at a time at warm idle, does each cylinder drop out (RPM reduces and you should "hear" it) and then return to operation when the idle screw is returned to its original position?
     
  3. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    I haven’t touched the mixtures yet. The highest carbs are just under 5 like 4.75.
    All idle air screws are closed
     
  4. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    I’m going to redo it but with a shim wedged to the cold start arm to raise the idle. It’s tough to do on the throttle cable
     
  5. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    There is still slop in the front carbs. Maybe one of the balls are worn to the rea
     
  6. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Also there is some slop in the pivot plate on the manifold crossover pipe that hold it
     
  7. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
  8. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,470
    Texas
    Full Name:
    Steve Magnusson
    That's a cool morning here in TX summer ;)
     
    Saabguy and absostone like this.
  9. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    I lost four pounds today;):). I redid this 5 times today and its not cooperating. I appreciate you guiding me through. and appreciate your help to Fchat
     
  10. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
  11. Saabguy

    Saabguy Formula 3
    Silver Subscribed

    Mar 28, 2012
    1,399
    Shreveport, LA
    Aaannndddd.... we are back to an A/C thread. ;-)

     
    thorn likes this.
  12. Saabguy

    Saabguy Formula 3
    Silver Subscribed

    Mar 28, 2012
    1,399
    Shreveport, LA
    Back in the day it meant to adjust in or out mixture screw to get max idle speed, then use idle speed screw to lower idle, then turn mixture in or out to get max idle, rinse and repeat. You will get to a point where turning in the screw (leaning the mixture ) will get max idle and ANY adjustment of the mixture will slow the idle.

    But that was back in the day.

    Lester

     
  13. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    lol. Please no!
     
  14. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    #39 absostone, Jul 31, 2019
    Last edited: Jul 31, 2019
    Well I’m convinced the linkage has been assembled too tight and too loose. off the throttle stops at 1500 rpms being pulled by the cable only I can adjust the idle by pushing or pulling on the carbs. Mikey no likey
     
  15. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Interesting. But I think I’ll stick with the 3 turns out to start. after I figure out this sticky linkage.
     
  16. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Ok I reset the balls. It’s better now. Best I have now is 4.5 to 5 kg. Is it possible the lowest front to rear adjuster is installed in such a way as to limit my synchronization?
     
  17. Saabguy

    Saabguy Formula 3
    Silver Subscribed

    Mar 28, 2012
    1,399
    Shreveport, LA
    I... I just can't let this get away. What balls did you reset??
     
  18. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Not the private ones. The linkage attachment pivot balls. I’ve set the throttle at 1500r with the cable 6 times already and got all carbs at 6.5-7kg at that 1500rpm. When I set to 1k rpm. The kgs are still 4.5 to 5kg
     
  19. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,470
    Texas
    Full Name:
    Steve Magnusson
    Good that the airflows are more even at those two throttle positions, but meaningless without setting the idle mixtures to reasonable positions, too. If your Synchrometer is reasonably accurate, the idle RPM would be much higher at those airflow rates and your advanced ignition setting. Based on the airflow being previously wacky, I wouldn't trust the old mixture settings as being sacred. You can adjust just one at a time, and, by counting turns to fully closed, you can always return it to the original position.
     
  20. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Thank you MR. Magnusson yes I was going to ask about mixture next. So the mixture will also change the kg? so if its too lean it would read high? I already started counting the existing turns.
     
  21. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,470
    Texas
    Full Name:
    Steve Magnusson
    Not directly, but it will change the idle RPM if you bring a cylinder from not contributing (from either being too rich or too lean) to contributing (or vice-a-versa); however, all airflows should change together equally whether the idle RPM goes up or down.
     
  22. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Ok I know I know 3.5 kg yes I know.
    Right now they are all 5 kg at idle. Drive it twice tonight. It idles really well. If I have time tomorrow I’ll set the mixture 3 turns out and open till it just loses rpm and turn back in 1/4-1:2 turn. But
    I think the best thing I should do is restart the front bank timing to 7 deg from 9 and do it all over again. But there is still 1/16 th slop in the carbs. Thing is the carbs had a lower over all kg In One of my earlier posts except for one that was just under 5 but it runs good
     
  23. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    So I just got around to counting the existing setting of all the mixture screws. So I got her warmed up. And for fun started turning a screw richer. I went two turns out in a few barrels and the idle did not change at all.
    So now what???
     
  24. absostone

    absostone F1 Rookie
    Silver Subscribed

    Jul 28, 2008
    4,397
    Fchat
    Bigger idle jets?
     
  25. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,470
    Texas
    Full Name:
    Steve Magnusson
    Two turns from where? If you move an idle screw from 0 turns (closed) to ~6 turns out and nothing ever changes that would be very odd and indicative of bigger problems.
     

Share This Page