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cure for sixpack idle screw weirdness- FIXED
#590509
01/21/10 11:17 PM
01/21/10 11:17 PM
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Joined: Mar 2003
Posts: 15,478
the boonies
aarcuda
OP
I Live Here
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the boonies
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i have a proble with the idle mixture screws on my sixpack idle screws on the center carb. I can turn them all the way in and the car still runs. figured that would mean its too rich, right? I should be able to get it to die with the screws in and make it idle rough turning them out far enough.
I adjust the idle to the highest vacuum and that seems to be with the screws all the way in (or maybe 1/16th out but that may be just my imagination.
I figured that its because my throttle is open too far. idle is set at 1000 to 1050. cam makes it idle real rough (240/245 dur at .050) so i cant idle much lower. idle vacuum is about 13. most ive ever seen is 14. in gear it drops to 7 to 9
I had the timing set at 18 adv, 20 adv and locked out at 30 and 34 adv but that doesnt give me any better idle screw mixture control. just for grins, ive had the initial timing all the way into the 40's.
so now I am locked out at 32 total (416 stroker). Drilled some holes in the throttle plates to lean it out and get more air in there but still the mixture screws are best at almost all the way in.
I have promax outboard baseplates so i have tried adjusting those up and down. at least they have effect on idle in and out. oh ya, and i have the promax center carb billet metering block so that has adjustable stuff on it too but i havent changed it from the settings it came with
so, how do I fix? i was going to try locking out timing at 32, leaning out the outboards and setting mixture on center first then working the outs.
I have another center carb that doesnt have holes in the throttle plates and the stock metering block to play with.
any advice would be appreciated.
i am pretty sure theres no vacuum leaks
It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop suspensions, cop shocks. It's a model made before catalytic converters so it'll run good on regular gas.
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Re: cure for sixpack idle screw weirdness
[Re: ScottSmith_Harms]
#590511
01/22/10 12:02 AM
01/22/10 12:02 AM
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Joined: Mar 2003
Posts: 15,478
the boonies
aarcuda
OP
I Live Here
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OP
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i will try it but i think ive been there before. but tomorrows another day with lots of time to play.
btw, my PV is a 3.5
It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop suspensions, cop shocks. It's a model made before catalytic converters so it'll run good on regular gas.
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Re: cure for sixpack idle screw weirdness
[Re: aarcuda]
#590512
01/22/10 05:33 AM
01/22/10 05:33 AM
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Joined: Feb 2005
Posts: 283
N.E. England
Roppa440
super street
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super street
Joined: Feb 2005
Posts: 283
N.E. England
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Put a vacuum gauge on the spark port of the center carb. If you have any vacuum there at idle your throttle blades are not closed enough. When vacuum drops to zero there your idle circuits will work well.
Bigger than stock cams need more air and or timing at idle. The first thing you need to do is find out how much initial timing you need for your engine.
More timing will increase the idle speed and allow you to close the throttle more.
For example. My 440 six pack has 26 degrees initial and 36 total at 3000rpm. It has a 237/242 @ 50 duration solid cam and I set idle speed at 900rpm so it runs nice and the alternator actually does something at that speed too.
If increasing the timing does not give you enough idle speed to get the center carb throttle closed then you need to start playing with the outboard carbs idle circuits or (last resort) drill a couple of 1mm holes in the throttle blades of the center carb.
2002 Chevrolet Corvette 5.7 LS1
2011 Alpha Romeo Giulietta Veloce 1.6 JTD
Because running a Mopar in the UK is getting TOO expensive!!
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Re: cure for sixpack idle screw weirdness
[Re: screamindriver]
#590514
01/22/10 11:41 AM
01/22/10 11:41 AM
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Joined: Feb 2005
Posts: 283
N.E. England
Roppa440
super street
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super street
Joined: Feb 2005
Posts: 283
N.E. England
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It was WAY too early in the morning for me when I read the initial post. I seem to have completely missed most of what you have tried to do to fix it. :-) I am a lot slower in the head than I used to be due to trauma so sometimes I just don't take in stuff correctly.
If drilling holes to let more air in did not increase the idle speed I wonder if it has a bad fuel leak?
A friend of mine had a bad leak that eventually was traced to the promax metering block being out of whack. It was leaking like a blown power valve.
Last edited by Roppa440; 01/22/10 11:43 AM.
2002 Chevrolet Corvette 5.7 LS1
2011 Alpha Romeo Giulietta Veloce 1.6 JTD
Because running a Mopar in the UK is getting TOO expensive!!
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Re: cure for sixpack idle screw weirdness
[Re: screamindriver]
#590516
01/22/10 10:51 PM
01/22/10 10:51 PM
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Joined: Mar 2003
Posts: 15,478
the boonies
aarcuda
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OP
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well, i got some good advice that seemed to work out perfectly.
Robx suggested i close the outboard mixture screws to 1/4 turn which i did. then I set the center at 1 1/2 out and see if the car will idle.
sure enough it did. i used a vacuum gauge to fine tune it but at the end of it all, i was at 1/2 out on the outboards and 1 1/2 or so for the center. i could turn the center screws in and watch the mixture change accordingly.
idled real nice. and the garage stopped getting smoked out.
seems to be running as good as it ever has. the real problem seems to be my outs were WAY too rich, so i had my center all wacked out on the transfer slots and the idle screws wouldnt work. really elementary but my baseline was so far off i got lost.
thanks rob!
It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop suspensions, cop shocks. It's a model made before catalytic converters so it'll run good on regular gas.
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Re: cure for sixpack idle screw weirdness
[Re: aarcuda]
#590517
01/23/10 12:03 AM
01/23/10 12:03 AM
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Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
RobX4406
I Live Here
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I Live Here
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Posts: 12,271
Overpriced Housing Central
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Quote:
well, i got some good advice that seemed to work out perfectly.
Robx suggested i close the outboard mixture screws to 1/4 turn which i did. then I set the center at 1 1/2 out and see if the car will idle.
sure enough it did. i used a vacuum gauge to fine tune it but at the end of it all, i was at 1/2 out on the outboards and 1 1/2 or so for the center. i could turn the center screws in and watch the mixture change accordingly.
idled real nice. and the garage stopped getting smoked out.
seems to be running as good as it ever has. the real problem seems to be my outs were WAY too rich, so i had my center all wacked out on the transfer slots and the idle screws wouldnt work. really elementary but my baseline was so far off i got lost.
thanks rob!
Usually 1/8-1/4 turn out seems to work pretty well. If it's still needing the center mix screws in a bit far, you can twist the outers in 1/16-1/8 turn then back out the center to get your idle mixture fine tuned.
Just make sure you don't have any lean spikes when transitioning to your outboards.
Sounds like you are closer to getting it right. Send me the datalogging you got. 
Your welcome and call any time as long as the dog isn't loose. 
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Re: cure for sixpack idle screw weirdness
[Re: RobX4406]
#590518
01/23/10 10:32 AM
01/23/10 10:32 AM
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Joined: Mar 2003
Posts: 15,478
the boonies
aarcuda
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i sent it out (so i thought) yesterday. but i sent it again this morning. i have to get it out on the road and see how it romps.
surprised toi see the lm1 plots showing changes to part throttle cruise just by changing the idle mixture. goes to show that the idle mixture adjustment plays a part in cruise and maybe to a lessor extent, wot... we'll see if it doesnt rain today
It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop suspensions, cop shocks. It's a model made before catalytic converters so it'll run good on regular gas.
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Re: cure for sixpack idle screw weirdness
[Re: aarcuda]
#590520
01/26/10 06:34 PM
01/26/10 06:34 PM
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Joined: Apr 2007
Posts: 332
NY
WICKD6PK
enthusiast
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enthusiast
Joined: Apr 2007
Posts: 332
NY
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Whoa nellie man this post is like dejavu all over again i had the same problem with my six pk set up turns out promax sent me the wrong center metering block and no matter what you did you couldnt adjust it.
when at idle you should be able to turn the mix screws all the way in and the motor should die on you
they sent me a new one problem solved.
now on the outboards i also have the jet conversion plates those things are awesome for tuning as well as the baseplate for the rear with the angled screws makes adjusting a whole lot easier.
if you put your fingers over the air bleeds on the top of the carb and the motor speeds up--too lean if it bogs --too rich and adjust your idle mix screws accordingly once you get it tuned you should have a mover there!
This better?
Last edited by WICKD6PK; 01/26/10 11:02 PM.
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Re: cure for sixpack idle screw weirdness
[Re: WICKD6PK]
#590521
01/26/10 09:47 PM
01/26/10 09:47 PM
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Joined: Jan 2003
Posts: 163
CT: Corrupticut
Mr71Bee
member
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member
Joined: Jan 2003
Posts: 163
CT: Corrupticut
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Quote:
Whoa nellieman this post is like dejavu all over again i had the same problem with my six pk set up turns out promax sent me the wrong center metering block and no matter what you did you couldnt adjust it when at idle you should be able to turn the mix screws all the way in and the motor should die on you anywho they sent me a new one problem solved now on the outboards i also have the jet conversion plates those things are awesome for tuning as well as the baseplate for the rear with the angled screws makes adjusting a whole lot easier if you put your fingers over the air bleeds on the top of the carb and the motor speeds up--too lean if it bogs --too rich and just adjust your idle mix screws accordingly once you get it tuned you should have a mover there
I am outa breath after reading this!
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Re: cure for sixpack idle screw weirdness
[Re: WICKD6PK]
#590524
01/26/10 11:13 PM
01/26/10 11:13 PM
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Joined: Mar 2003
Posts: 15,478
the boonies
aarcuda
OP
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i understood it fine i can read pretty well and know where to punctuate so even if you dont use them my mind is so advanced that it inserts them in the correct position i dont need no stinking dots they just add detail
It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop suspensions, cop shocks. It's a model made before catalytic converters so it'll run good on regular gas.
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Re: cure for sixpack idle screw weirdness
[Re: rbstroker]
#590528
01/27/10 12:03 PM
01/27/10 12:03 PM
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Joined: Mar 2003
Posts: 15,478
the boonies
aarcuda
OP
I Live Here
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OP
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Quote:
Quote:
well, i got some good advice that seemed to work out perfectly.
Robx suggested i close the outboard mixture screws to 1/4 turn which i did. then I set the center at 1 1/2 out and see if the car will idle.
sure enough it did. i used a vacuum gauge to fine tune it but at the end of it all, i was at 1/2 out on the outboards and 1 1/2 or so for the center. i could turn the center screws in and watch the mixture change accordingly.
idled real nice. and the garage stopped getting smoked out.
seems to be running as good as it ever has. the real problem seems to be my outs were WAY too rich, so i had my center all wacked out on the transfer slots and the idle screws wouldnt work. really elementary but my baseline was so far off i got lost.
thanks rob!
Any suggestions on setting up the idle circuits on a completely stock 1970 six pack setup? It is super rich at idle right now.
first off, can you turn the idle mixture screws in and make the motor idle rough? if so, just turn them in untill it runs smooth and shows the highest idle vacuum (go buy a vacuum gauge).
If you cant lean it out with the mixture screws, you are probably in the same situation i was in- the throttle plates might be open too much and youre running on the intermediate circuit and not the idle circuit.
Check your timing and set it at 8 before TDC or so. set the mixture screws at 1 1/2 turns out and see if you can get the idle screw (not the mixture screw but the idle screw for the throttle plates) backed off a bit to get the carb on the idle circuit.
The problem with stock sixpacks is the outboards run lean. so you may have had to turn the center idle mixture screw out further to compensate, then turned up the idle to get it to run. and that puts you on the transfer circuit which will put you rich.
the outboards have mixture screws in the base plates under a lead plug you can remover pretty easily. then, if your lucky, you can turn the outbard mixture screws out a 1/4 turn to richen them up and then get the center carb dialed in
It's got a cop motor, a 440 cubic inch plant, it's got cop tires, cop suspensions, cop shocks. It's a model made before catalytic converters so it'll run good on regular gas.
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..But it's still a good suggestion for other guys trying to get the idle right...
...Just curious...Was it a manufacturing defect or did the block warp during use somehow ??? First time I've heard of that problem..
. But it makes perfect sense to me 
