Re: 440 "lunging" at low speed
[Re: 70VERT]
#1663714
08/26/14 01:01 AM
08/26/14 01:01 AM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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Are you down around idle when this happens?
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: 440 "lunging" at low speed
[Re: 70VERT]
#1663716
08/26/14 10:04 AM
08/26/14 10:04 AM
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Joined: Nov 2008
Posts: 1,565
tennessee
pushbutton
pro stock
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pro stock
Joined: Nov 2008
Posts: 1,565
tennessee
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Quote:
My 70 Plymouth 440 (4 speed) has been "lunging" when I coast at low speeds. It idles fine and runs out great through the gears. Only time I notice it is when I am 2,3, or 4th and just kinda coasting at low speeds.....440, Holley 750 Street Avenger,stock heads, Edelbrock Performer manifold and Hughes Whiplash cam. Can you guys give me some advice on what might be going on here and how to straighten it out? Thanx
Do you have the vac advance hooked up? If you do try disconnecting and plugging the hose. See if it helps.
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Re: 440 "lunging" at low speed
[Re: 70VERT]
#1663717
08/26/14 10:59 AM
08/26/14 10:59 AM
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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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Clarify the lunging: are you coasting down with foot off of the pedal. Are you at a steady speed. what RPM/how much throttle (load/in hg)
live every 24 hour block of time like it's your last day on earth
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Re: 440 "lunging" at low speed
[Re: 70VERT]
#1663718
08/26/14 02:36 PM
08/26/14 02:36 PM
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Joined: Aug 2003
Posts: 43,173
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,173
Bend,OR USA
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Do you have a tach in the car? If os go drive it and give us the RPM it does the surging at, is the clutch out or in also  ?
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 440 "lunging" at low speed
[Re: Cab_Burge]
#1663719
08/26/14 02:45 PM
08/26/14 02:45 PM
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Joined: Jan 2011
Posts: 15,864
Central Florida
larrymopar360
Stud Muffin
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Stud Muffin
Joined: Jan 2011
Posts: 15,864
Central Florida
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RapidRobert and PushButton have some good thoughts here. If you are on the gas still (although coasting doesn't sound like it but clarify please) I think PushButton has a good suggestion. I had some lunging or surging on one of my 360's that went away when I started running it w/o the vac advance connected.
If not on the gas, and in 4th or even 3rd, then it does sound like you may be in too high a gear.
Last edited by larrymopar360; 08/26/14 07:21 PM.
Facts are stubborn things.
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Re: 440 "lunging" at low speed
[Re: 70VERT]
#1663720
08/26/14 04:06 PM
08/26/14 04:06 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
My 70 Plymouth 440 (4 speed) has been "lunging" when I coast at low speeds. It idles fine and runs out great through the gears. Only time I notice it is when I am 2,3, or 4th and just kinda coasting at low speeds.....440, Holley 750 Street Avenger,stock heads, Edelbrock Performer manifold and Hughes Whiplash cam. Can you guys give me some advice on what might be going on here and how to straighten it out? Thanx
440+750carb=lean.
My guess is a lean surge is what your experiencing. Just my guess. Jet it up some and see if I'm right. When you unplug the vacuum advance you are just applying a band aid and missing out on good cruise power and mileage.
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Re: 440 "lunging" at low speed
[Re: Challenger 1]
#1663725
08/27/14 02:29 AM
08/27/14 02:29 AM
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Joined: Jan 2008
Posts: 553
DE
Ply72rr
mopar
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mopar
Joined: Jan 2008
Posts: 553
DE
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Quote:
Quote:
My 70 Plymouth 440 (4 speed) has been "lunging" when I coast at low speeds. It idles fine and runs out great through the gears. Only time I notice it is when I am 2,3, or 4th and just kinda coasting at low speeds.....440, Holley 750 Street Avenger,stock heads, Edelbrock Performer manifold and Hughes Whiplash cam. Can you guys give me some advice on what might be going on here and how to straighten it out? Thanx
440+750carb=lean.
My guess is a lean surge is what your experiencing. Just my guess. Jet it up some and see if I'm right. When you unplug the vacuum advance you are just applying a band aid and missing out on good cruise power and mileage.
Unplugging the vacuum advance to see if the surge goes away could be a good test, if it does stop the surge maybe an adjustment to the Vacuum advance with a allen wrench would take care of the problem. The instructions that came with my MP ignition kit mentioned a low speed surge could be caused by this.
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Re: 440 "lunging" at low speed
[Re: Ply72rr]
#1663726
08/27/14 10:52 AM
08/27/14 10:52 AM
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Joined: Jun 2006
Posts: 5,161
CT
GTX MATT
master
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master
Joined: Jun 2006
Posts: 5,161
CT
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You're at 1000 rpm or less at 10 mph in second gear, I think your problem IS that you need to downshift. Additionally this is not a stock engine, and doesn't pull as much vacuum at that speed. More initial timing might help it.
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: 440 "lunging" at low speed
[Re: 70VERT]
#1663727
08/27/14 11:11 AM
08/27/14 11:11 AM
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Joined: Jan 2003
Posts: 75,008
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,008
U.S.S.A.
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Quote:
Basically, it's at low RPMs with very little throttle. For instance 2nd gear around 10mph, it'll surge up and down enough to clang the drive train. 3rd gear comparable only at a little higher speed.
I know enough when to downshift, thats not it.
Why are you in second gear at 10mph with 3.55's ???
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Re: 440 "lunging" at low speed
[Re: Challenger 1]
#1663728
08/27/14 11:11 AM
08/27/14 11:11 AM
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Joined: Jul 2012
Posts: 323
Endicott, NY, USA
crazyjjk
enthusiast
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enthusiast
Joined: Jul 2012
Posts: 323
Endicott, NY, USA
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Quote:
Quote:
My 70 Plymouth 440 (4 speed) has been "lunging" when I coast at low speeds. It idles fine and runs out great through the gears. Only time I notice it is when I am 2,3, or 4th and just kinda coasting at low speeds.....440, Holley 750 Street Avenger,stock heads, Edelbrock Performer manifold and Hughes Whiplash cam. Can you guys give me some advice on what might be going on here and how to straighten it out? Thanx
440+750carb=lean.
My guess is a lean surge is what your experiencing. Just my guess. Jet it up some and see if I'm right. When you unplug the vacuum advance you are just applying a band aid and missing out on good cruise power and mileage.
I would also be inclined to believe it is a lean surge.
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