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Whats my next step for solving my light-throttle surge?
#1207100
03/31/12 06:06 PM
03/31/12 06:06 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
OP
super stock
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OP
super stock
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Posts: 817
Eugene, Oregon
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Awhile ago when I first installed my Carter AVS, I had an off-the-line stumble that ended up being mostly solved by going back to the original rubber accelerator pump.
I'm still having a problem with a very light throttle surge at very low RPM, with the rpm audibly wavering up and down just a bit unless I give it more gas when cruising at around 25-35. Today I tried opening up the idle mixture screws another 3/4 turn each and it didn't make a difference. Before I sent my whole dizzy off to FBO I tried fiddling with the vacuum advance and it didn't really change anything.
I've read some people recommend a couple of small holes in the throttle blades to allow the idle circuit to work better - would this be a good thing to try it if seems to be free of any misbehavior everywhere else in the driving range? If I try getting the engine warm and then turning down the idle as far as can in drive and it seems better, might this be a solution?
I've also read about drilling out the idle compensators, but I don't want to go buying a set of wee drill bits and yet another gasket set for this thing if I can do something simpler first.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Whats my next step for solving my light-throttle surge?
[Re: rbstroker]
#1207102
03/31/12 06:22 PM
03/31/12 06:22 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
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OP
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Eugene, Oregon
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Yes, this only happened after changing the carb. This is for my 318 wagon in my sig.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Whats my next step for solving my light-throttle surge?
[Re: Secret Chimp]
#1207105
03/31/12 07:36 PM
03/31/12 07:36 PM
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Joined: Mar 2003
Posts: 4,848
Memphis
HemiRick
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master
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Memphis
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I agree lean and to fix this properly you need some smaller diameter metering rods.
Take care,
Rick
68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451
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Re: Whats my next step for solving my light-throttle surge?
[Re: topside]
#1207107
03/31/12 07:42 PM
03/31/12 07:42 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
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OP
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Eugene, Oregon
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Couldn't I be lean in just the idle circuit though? This doesn't happen unless I'm just within the first crack of the throttle to maintain speed on a slight grade in town. Everywhere else it doesn't stumble or surge at all.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Whats my next step for solving my light-throttle surge?
[Re: Secret Chimp]
#1207111
04/01/12 08:49 AM
04/01/12 08:49 AM
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Joined: Nov 2003
Posts: 5,048
Atlanta Indiana
Dave Watt
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Atlanta Indiana
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Quote:
Couldn't I be lean in just the idle circuit though? This doesn't happen unless I'm just within the first crack of the throttle to maintain speed on a slight grade in town. Everywhere else it doesn't stumble or surge at all.
Since you are driving down the road when it's happening, the carburetor is now using the primary jetting. Try going one step larger on the primary jets and the lean surge should go away.
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Re: Whats my next step for solving my light-throttle surge?
[Re: Secret Chimp]
#1207114
04/01/12 04:06 PM
04/01/12 04:06 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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next larger jet(s) in your strip kit. a .003" larger jet is a much richer change than a .003" smaller rod
live every 24 hour block of time like it's your last day on earth
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Re: Whats my next step for solving my light-throttle surge?
[Re: Secret Chimp]
#1207115
04/01/12 04:51 PM
04/01/12 04:51 PM
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Joined: Jan 2003
Posts: 75,058
U.S.S.A.
JohnRR
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I Win
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Quote:
In drive it's around 12.
What spring do you have in the primary wells ? Do you have the B rock tuning kit with jets rods and springs ? or just the spring kit ? What carb is this the one you got off ebarf ?
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Re: Whats my next step for solving my light-throttle surge?
[Re: lewtot184]
#1207116
04/01/12 05:19 PM
04/01/12 05:19 PM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
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usa
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Quote:
enlarge the idle feed tube orifice in the primary clusters.
i guess you folks don't understand this,  .
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Re: Whats my next step for solving my light-throttle surge?
[Re: lewtot184]
#1207117
04/01/12 11:29 PM
04/01/12 11:29 PM
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Joined: Jan 2003
Posts: 75,058
U.S.S.A.
JohnRR
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I Win
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Quote:
Quote:
enlarge the idle feed tube orifice in the primary clusters.
i guess you folks don't understand this, .
He is using a factory stock 440 carb on his 318 , I'd change the step springs before modifying things , but that's me ...
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Re: Whats my next step for solving my light-throttle surge?
[Re: JohnRR]
#1207118
04/02/12 12:17 AM
04/02/12 12:17 AM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
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OP
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Eugene, Oregon
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It's a Carter AVS 4966S. I haven't touched any of the internals, including the springs. If nobody previously changed the primary jetting, it has .089 primaries with .066/.063/.058 metering rods. I'm not sure if Edelbrock springs work with the long AVS metering rods or if I'd need to convert to Edelbrock jets and rods (and use flat covers) first.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Whats my next step for solving my light-throttle surge?
[Re: Secret Chimp]
#1207119
04/02/12 12:54 AM
04/02/12 12:54 AM
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Joined: Jan 2003
Posts: 75,058
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,058
U.S.S.A.
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Quote:
It's a Carter AVS 4966S. I haven't touched any of the internals, including the springs. If nobody previously changed the primary jetting, it has .089 primaries with .066/.063/.058 metering rods. I'm not sure if Edelbrock springs work with the long AVS metering rods or if I'd need to convert to Edelbrock jets and rods (and use flat covers) first.
ebrock springs should work , travel is limited by the cap , it has to be right for the number of steps on the rod .
With 12 you are below stock vacuum , so trying a spring change to one for that rated vacuum would be a good idea .
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Re: Whats my next step for solving my light-throttle surge?
[Re: JohnRR]
#1207120
04/02/12 10:21 AM
04/02/12 10:21 AM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
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master
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Posts: 3,916
usa
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Quote:
Quote:
Quote:
enlarge the idle feed tube orifice in the primary clusters.
i guess you folks don't understand this, .
He is using a factory stock 440 carb on his 318 , I'd change the step springs before modifying things , but that's me ...
i know, but why would you go after the main metering for an off idle problem?
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Re: Whats my next step for solving my light-throttle surge?
[Re: Secret Chimp]
#1207121
04/02/12 10:35 AM
04/02/12 10:35 AM
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Joined: Dec 2007
Posts: 1,357
central Florida
VL21
pro stock
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pro stock
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Posts: 1,357
central Florida
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This is just a shot in the dark, have had it before. Are you running a vacuum advance? If so, do you have it connected to ported or manifold vacuum source? I have had manifold vacuum under light or no throttle advance the timing so far it would cause something like your symptoms. Just a thought. 
It takes gasoline to interest me.
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Re: Whats my next step for solving my light-throttle surge?
[Re: lewtot184]
#1207122
04/02/12 10:39 AM
04/02/12 10:39 AM
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Joined: Jan 2003
Posts: 75,058
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
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U.S.S.A.
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Quote:
Quote:
Quote:
Quote:
enlarge the idle feed tube orifice in the primary clusters.
i guess you folks don't understand this, .
He is using a factory stock 440 carb on his 318 , I'd change the step springs before modifying things , but that's me ...
i know, but why would you go after the main metering for an off idle problem?
It doesn't sound like an off idle problem to me , but what do I know
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