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idle drops on stops (6 pack)
#1630501
06/08/14 05:16 PM
06/08/14 05:16 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
OP
master
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OP
master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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New to 6 packs, this is the MECHANICAL not stock vacuum set up. Anyway, 11.25cr, ported J's, small solid cam 244/252 @.050 cam 365ci engine timing is at 20 initial 30 total, idles in park at 950 drive about 800/850. engine temp is running about 190, center jets 64 car has a 4,400 stall. Idles and cruises fine when the mechanical outboards are opened its like being shot out of a cannon, very wicked! only thing so far on the short rides is when coming to a stop the idle dips to around 500 then after about 3/4 seconds recovers. floats are set at the bottom of the sight hole, just barely dribbling out. Any advise? the outboards have no idle screws but do contribute to idle.
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Re: idle drops on stops (6 pack)
[Re: ademon]
#1630505
06/08/14 09:31 PM
06/08/14 09:31 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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You might raise the fuel a bit (first in the center carb then in the outers) & see how it responds then lower it a bit (from where it is now) & see how it responds. If you can lower the idle to 500 what is the initial at that point?
live every 24 hour block of time like it's your last day on earth
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Re: idle drops on stops (6 pack)
[Re: TJP]
#1630507
06/08/14 10:40 PM
06/08/14 10:40 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
OP
master
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OP
master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Thanks, it's a MSD 6al, timing 20 initial, no vacuum, 30 total. It's steady and I have a bit stiffer springs in it so total comes in at around 2,800. It has a dynamic 9.5" converter that flashes at 4,400 so no real need for timing to come in fast. I'll try the float settings. Was a bit surprised it handles all this carburation, it really rips when the outboards open!
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Re: idle drops on stops (6 pack)
[Re: MO_PA]
#1630510
06/09/14 06:49 PM
06/09/14 06:49 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
OP
master
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OP
master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
More timing!
Really ? After I hit about 18/19 vacuum and idle didn't do much
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Re: idle drops on stops (6 pack)
[Re: ademon]
#1630512
06/16/14 12:30 PM
06/16/14 12:30 PM
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Joined: Jan 2003
Posts: 15,355
Omaha Ne
TJP
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,355
Omaha Ne
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Silly question, Where do you have you secondary idle screws set???? They have to be equal and the linkage rod that connects them has to be "floating" hope this makes sense  BTW I have run many of these setups over the years and currently have one on my 340. I have always run the floats at the bottom of the sight hole. Typically 10 to 15 initial and never had the issues you're experiencing.
Last edited by TJP; 06/16/14 02:04 PM.
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Re: idle drops on stops (6 pack)
[Re: TJP]
#1630516
06/16/14 02:55 PM
06/16/14 02:55 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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Did you install the little plastic Holley anti-slosh tube in the metering blocks? I know it's more for acceleration with the way these carbs are oriented, but it doesn't hurt to have it in there.
You may also have some blockage in your center metering block emulsion orifices. Is your vacuum advance hooked above or below the throttle blades. What's your fuel pressure?
Vacuum advance must be hooked up to manifold vacuum to work correctly. ie the timing retards when manifold vacuum drops( gas pedal is pushed) and advances it's full amount at idle and up to up to around 50 degrees total when under light load at full mechanical advance on the road etc at high manifold vacuum for maximum fuel economy and torque off idle. It drastically improves drivability around town this way.
You can try lowering the float level in the outboards, or disconnecting them from the fuel supply AND linkage to isolating your center carb until you get this nailed down.
I sent my carbs to Ben at Promax. After giving him my engine specs, they added their metering block. That combined with the use of a wide band to dial it in. It's nothing short of amazing how well it runs.
Last edited by jbc426; 06/16/14 03:10 PM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: idle drops on stops (6 pack)
[Re: TJP]
#1630518
06/16/14 06:36 PM
06/16/14 06:36 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
OP
master
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OP
master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
Silly question,
Where do you have you secondary idle screws set????
They have to be equal and the linkage rod that connects them has to be "floating" hope this makes sense
BTW I have run many of these setups over the years and currently have one on my 340. I have always run the floats at the bottom of the sight hole. Typically 10 to 15 initial and never had the issues you're experiencing.
before I installed the outboards I made sure the transfer slot was squared .040 or so window. Once running I tuned it and may have just slightly opened a bit more but not to the point where they would start pulling from the mains, there is no fuel dribble from any carb and was carfull not to open the throttle blades to much loosing my idle circuit. It's at 950 park and drops to about 800 in gear.
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Re: idle drops on stops (6 pack)
[Re: Cab_Burge]
#1630519
06/16/14 06:41 PM
06/16/14 06:41 PM
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Joined: Sep 2004
Posts: 6,906
IL, Aurora
ademon
OP
master
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OP
master
Joined: Sep 2004
Posts: 6,906
IL, Aurora
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Quote:
Check the ignition curve at idle in nuetral with the motor running and then in low gear to see if it is retarding in gear, even a little will affect the idle RPM. Make sure and leave the vacume advance hook up when checking it  Let us know what you find, all problems have solutions  The problem is identifyingthe problem correctly and the using the correct solution  
Thanks, I'm running a MSD 6AL, with the pro billet distributor. No vacuum advance on it it's set at 22 initial about 33 total. I have heavier springs in it so total happens about 2,500rpm, the idle timing stays right at 22.
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