440-6 hesitation from idle?
#1170335
02/02/12 12:11 AM
02/02/12 12:11 AM
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Joined: Jan 2003
Posts: 1,177 People's Republic of Kali
70runner
OP
super stock
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OP
super stock
Joined: Jan 2003
Posts: 1,177
People's Republic of Kali
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10:1 compression, Lunati 60303, alum heads, stock manifolds, auto, new 71 repro carbs (6.5PV, #65 jets, #35 squirter, with blue cam), 18deg base timing, 14in vacuum @ idle. Engine starts and idles fine, though rich as center partially on the idle transition circuit. Idle originally 12.8 on AF meter. Widened the outboard plate holes 2 drill# sizes, from .082 to .089, which improved AF to 13.5, still a bit rich. Still debating whether to drill center plate or continue drilling outboards or ???
Noticeable hesitation when revving from idle in park (car not on the road yet).
Thots?
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Re: 440-6 hesitation from idle?
[Re: 70runner]
#1170338
02/02/12 03:32 AM
02/02/12 03:32 AM
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Joined: Jan 2003
Posts: 2,001 s. e. pa.
calrobb2000
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,001
s. e. pa.
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hi i did not get good idle till i had outboards 1 turn out ? also would help hesitation prob at this setting , and may allow turning in center carb screws ? what is vac in gear warm ? fuel bowel screws center carb not snug enuf can cause too rich idle ! still not working drill center carb start at .080 . also had a bad <week>resistor cause this condition !
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Re: 440-6 hesitation from idle?
[Re: Mr.Yuck]
#1170340
02/02/12 05:04 PM
02/02/12 05:04 PM
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Joined: Jan 2003
Posts: 1,177 People's Republic of Kali
70runner
OP
super stock
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OP
super stock
Joined: Jan 2003
Posts: 1,177
People's Republic of Kali
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Setting floats a hair low...just below the sight hole instead of right at it? Float levels are current dribbling on outboards, level with sight hole on center. Stock (new) fuel pump working OK, approx 6psi. The "back out 1.25" apply to the outboards or center? The 14in vacuum at idle is in gear; approx 15" in park. I welded the slot in the dizzy to get approx 38deg all in. Using points now, plan to eventually go with pertronix. Don't know enough about carb design to determine if the hesitation and rich idle are related. I've tried different jets, little effect on the rich idle. Verified PV is working and should be OK for my vac levels. Rechecked accelerator pump lever clearance. This can get pretty frustrating. I'd like to solve this without drilling if possible. Thx for
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Re: 440-6 hesitation from idle?
[Re: Mr.Yuck]
#1170343
02/02/12 10:42 PM
02/02/12 10:42 PM
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Joined: Jan 2003
Posts: 1,177 People's Republic of Kali
70runner
OP
super stock
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OP
super stock
Joined: Jan 2003
Posts: 1,177
People's Republic of Kali
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Quote:
Yes the screws are the primary... and yes set the floats a hair lower than you would w/ a 4bbl. I haven't even touched my outboard screws ever... maybe I should...lol What is your idle rpm? I have to have mine at 900-1000 but I have a solid roller...
idle at about 900 in park
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Re: 440-6 hesitation from idle?
[Re: BSB67]
#1170344
02/02/12 11:18 PM
02/02/12 11:18 PM
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Joined: Jan 2003
Posts: 1,177 People's Republic of Kali
70runner
OP
super stock
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OP
super stock
Joined: Jan 2003
Posts: 1,177
People's Republic of Kali
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Quote:
The six pack is not the greatest place to begin your carb tuning experiance. Also, stabbing the throttle in neutral is not the best way to determine the status of the tune. Why don't you take it for a ride? What is your neutral and in gear idle rpm?
Re tuning experience - no doubt, but I'm determined. Its just about ready for road trials, clearing up some brake valve leaks. Neutral idle about 900, drops to about 850 in gear.
Quote:
Based on what you've said and reading probably a little more into it, these are my recommendations for starters:
1) Make sure you don't have a vacuum leak. 2) Set the floats as they are designed to be set, at the bottom of the sight hole. 3)Adjust the outboard carb idle mixture screws to 3/4 turn out. 4)Make sure your center carb squirter squirts fuel at the first movement of the throttle.
Try these and report back.
I had an internal intake vac leak the first time around, but I believe that's fixed now. Floats are set per specs: outboards dribbling, center at bottom of sight hole.
Adjusted the outboards until plugging each air bleed produced no change in rpm/vac, probably ended up around 1/2 turn out. This seemed to be a popular method.?.
I'll check the squirter and advise.
Here's a vid of the idle (set a little high):
Idle
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Re: 440-6 hesitation from idle?
[Re: 70runner]
#1170345
02/03/12 10:06 AM
02/03/12 10:06 AM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Not saying this is the rightway to do it, but when I set mine up for the 1st time it was on a 11:1 440 w/ a 528 solid cam lashed tight. I checked the floats before I installed the car..how? I flipped them upside down...hahah I primed the center carb only, left the out boad rods unhooked, turned the mixture screws all the way in then back out 1.25 turns...I set my full timing then initail and finally tuned for best vaccuum at 800rpm. Then I hooked up the outboards. I checked the floats, they were a tad low but not enough to worry about. I shut the car off, then I had my son floor the car and I opened the ooutboards by hand to make sure I had 100% throttle. Worked fine. Usually when holley carbs "dribble" as you state the floats are high. That or you need to adjust your outboard rods. With your cam your outboards should be shut, you shouldn't need to drill the holes any bigger. My cam has a duration of 292/297 (254/260@.050) and I didn't need to open mine up. I think you are close, you just need to fine tune it.
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Re: 440-6 hesitation from idle?
[Re: Mr.Yuck]
#1170346
02/03/12 12:00 PM
02/03/12 12:00 PM
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Joined: Jan 2006
Posts: 587 IL . usa
cjs69mope
mopar
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mopar
Joined: Jan 2006
Posts: 587
IL . usa
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you said in one post that you rechecked the accelerator pump clearance? This is where i would look again there is a lot of misleading info on how to properly adjust the accelerator pump lever adjustment out there. By reading and listening to what you are saying is the motor is hesitating when you quickly open the throttle Right? Ok that is most often due to insufficient amount of accelerator pump shot or not quick enough shot . Does the accelerator pump squirt like popping a zit or does it dribble when you barely move the throttle lever? I have had this problem before on many holley's because people read the Holley tune ing books and always try and adjust the lever to have .015 clearance between the pump lever and the spring bolt at WOT This is where i think the problem comes from . The way i adjust the pump is like this i take the cam off and see how well the pump squirts with me moving the lever with my finger also i watch very closely how far up the lever returns when the pump is at rest. Then i make the spring bolt adjustment so the bolt is very short. then install the cam in the original factory position. Now the lever and pump arm should be very loose and this is where you need to be to start. Now slowly and very carefully start to lengthen the bolt adjustment so it just barely touched the pump lever at it resting position! This is the most important part! the adjustment should be so that the pump is getting full stroke! You do not know how many holley's i have fixed with this simple adjustment if the pump is getting full stroke i bet your problem will go away . Cj
1969 Dodge Charger
1969 Dodge Superbee
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