| Author |
Message |
Paul Newman (Newman)
Junior Member
Username: Newman
Post Number: 218
Registered: 12-2001
| | Posted on Tuesday, June 11, 2002 - 12:51 pm: | |
All Robert asked is for a simple way to raise the idle not sync the carbs. Turn the idle speed screw on each left hand side carb equal turns to get the idle you want. If the car runs fine and the carbs were synced in the past, why do it again to raise the idle? |
'75 308 GT4 (Peter)
Intermediate Member
Username: Peter
Post Number: 1873
Registered: 12-2000
| | Posted on Tuesday, June 11, 2002 - 12:35 am: | |
Steve is right. Opening throttle plates will raise idle RPM.
My technique:
-Disconnect linkages and throttle cable
-Turn in throttle shaft stop screws first (which are on the body of the carbs, Steve's GT4 WSM source, screw "A"), balance the interconnecting, opposite carb accordingly (the one that shares the same "shaft" using the sector link, source: screw "B")
-Balance individual throats of each carb using screw "D"
-Fine adjustments are made using a rubber tube shoved in your ear-canal on one end, the other end down the carb throat. Listen for dull, muted popping. Makes sure whatever you hear, its the same on every throat. STE synchrometer readings should be around 3.5.
I found my mixture screws to be spot-on at the required three-turns in. |
Steve Magnusson (91tr)
Member
Username: 91tr
Post Number: 768
Registered: 1-2001
| | Posted on Monday, June 10, 2002 - 3:34 pm: | |
Rob -- Not sure that I understand your question as "syncing the carbs" includes setting the idle speed -- just increase the total airflow by opening the throttle plates more to raise the RPM (but you may need to then reset the ignition timing). "Syncing the carbs" to me means:
1. operating at the desired idle (1000) RPM,
2. the ignition advance should be where you want/desire it,
3. the individual barrel flows should be near equal, and
4. the idle mixture is right for the 1000 RPM airflow.
It should mostly be a case of tweaking the "A" screw (Fig 19 page C20 in the 308GT4 WSM) on each bank (and resetting the mixtures/timing as required). |
Paul Newman (Newman)
Junior Member
Username: Newman
Post Number: 215
Registered: 12-2001
| | Posted on Monday, June 10, 2002 - 3:20 pm: | |
If the rear carbs are linked rt and lt and the front carbs are linked rt and lt, adjust the idle screw on the front left(this controls both front carbs equally)and do the same for the left rear carb(which controls the right rear one equally) make sure you turn the screws the exact same amount such as 1/4 turn in each. Im sure someone will say this will screw the balance but Ive messed with my idle using this method and had no ill effects. You can always put them back where they were if you count the turns. |
Robert W. Garven Jr. (Robertgarven)
New member
Username: Robertgarven
Post Number: 37
Registered: 2-2002
| | Posted on Monday, June 10, 2002 - 2:33 pm: | |
Guys,
As many of you know I was having some noise which I thought was coming from my transfer gears. I replaced all the bearings, installed a new clutch,
and I am still experiencing some slight chatter. A ferrai mechanic suggested that my idle speed which is around 600 rpm is way to low and that might be causing the noise.
I have several posts about syncing the carbs, but no simple directions for raising the idle speed.
I have a 75 gt4
Thanks for any help,
Rob |