Author Topic: Idle just won't smooth out in gear  (Read 3528 times)

Offline TRIPLE-GREEN

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Idle just won't smooth out in gear
« on: December 07, 2014 - 10:05:58 PM »
Hello guys,
Info: 1973 Dodge challenger with a 318 - 4brl Edelbrock carb. - Automatic Trans.

   It has been some time since the last time I used your wealth of knowledge, but this time I just don't know what to do. After a year of storage I got the challenger out and started working on her again. I replaced an old fuel pump and put in a new flex fan. Thinking my problem was an electrical one I removed the old electric fan because it just drew to much power. My challenger hates new tech. No matter how much I try she rejects anything that was not available in the 70's. So fine I have a great new mechanical fan that works great.
   Sorry let me get to the point. The car idles great when out of gear. But when I drop it into gear it gets this little rumble in it like it wants to stall ever few seconds. Turning on the headlights seems to increase the waddle. Removing the fan really helped this because before when I turned on my headlights while the electric fan was running it would just stall. I have checked for a vacuum leak but don't see anything.

One thing that stuck me as odd. The plastic fuel filter I have between the new mechanical fuel pump and the carb runs almost empty as the engine runs. While the car idles it will burp up some more fuel every few seconds but it never really fills up past the bottom of the filter. Could that be the issue?

Note the car runs and drives like a dream. It just has a crap idle when you get to a light.
Any help would be great. I need to get her road worthy asap and this is my only issue.
« Last Edit: December 07, 2014 - 10:07:31 PM by TRIPLE-GREEN »




Offline jimynick

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Re: Idle just won't smooth out in gear
« Reply #1 on: December 07, 2014 - 10:18:22 PM »
I don't know, it sounds more electrical to me. I'd put a meter across the battery terminals and see what you've got at an idle out of gear. It should be in the high 13 to mid 14 volts. Based on what you said, it may be that the alternator just can't supply the voltage to run the ignition effectively at a lower rpm. There's been a few threads about the voltage requirements at the ballast resistor that you should check as well and there's others here that're a lot smarter than I in this vein. Good luck  :wave:

Offline TRIPLE-GREEN

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Re: Idle just won't smooth out in gear
« Reply #2 on: December 07, 2014 - 11:25:33 PM »


Ok I am going to sound like a complete moron but I have a tester a lot like this. I got it removed it from the package and never bothered to look and see how it fricken works. So I don't know which setting to use to get the voltage. Any help?

Offline cudabob496

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Re: Idle just won't smooth out in gear
« Reply #3 on: December 08, 2014 - 02:41:38 AM »


Ok I am going to sound like a complete moron but I have a tester a lot like this. I got it removed it from the package and never bothered to look and see how it fricken works. So I don't know which setting to use to get the voltage. Any help?


For battery, select DCV 20.  Practice on a home outlet by first selecting ACV 200,
and see if you get around 125 V.
also,for later use, to check if plug wires are good, select OHM 2000 to start.
« Last Edit: December 08, 2014 - 02:45:52 AM by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline cudabob496

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Re: Idle just won't smooth out in gear
« Reply #4 on: December 08, 2014 - 02:42:44 AM »
up idle to 1000 rpm.
Some weak or poor alternators don't so well at low rpm.
Verify timing is good too!  At idle, try 15 degrees BTDC.
When you increase your idle timing, it will also increase your idle speed,
so may have to lower idle speed back down a little.
make sure engine is well grounded
« Last Edit: December 08, 2014 - 04:17:57 AM by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline Bullitt-

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Re: Idle just won't smooth out in gear
« Reply #5 on: December 08, 2014 - 08:53:09 AM »
I suspect your idle transition slots are exposed... ck this article.
http://www.superchevy.com/how-to/45638/

Mine would start & idle good but die when put in gear or of it didn't die would stumble badly as accelerator was depressed.
When I figured the idle transition slot with the carb off the car I set the idle screw then installed carb, adjusting idle speed with engine timing/mixture screws. .
Sounds backward but it worked for me.
Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
Screwed by Photobucket!

Offline 734406pk

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Re: Idle just won't smooth out in gear
« Reply #6 on: December 08, 2014 - 10:46:55 PM »
I agree with Bullitt, sounds like the idle mixture is lean. Have you tried adjusting the mixture screws?
1973 Challenger 440 6 pack auto 3.91 rear
2012 Dodge Ram 3500 dually 6.7 Cummins Fleece EFI Live
1973 Challenger 318 2bbl auto 2.73 rear 22.5 mpg RIP
1970 Challenger TA 340 4bbl auto-Sold and sad
1999 Dodge Ram 3500 dually 5.9 Cummins Fleece tuned VGT-sold
1995 Kawasaki ZX1100E & still alive

Offline TRIPLE-GREEN

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Re: Idle just won't smooth out in gear
« Reply #7 on: December 12, 2014 - 12:00:44 AM »
I wanted to offer an update. I want to thank you all for your help. I adjusted the screws bumped the idle a little and the car has run pretty much perfect since. It still gets a little fussy when having to sit in traffic or stopped for to long with the headlights on. I found the issue is directly linked to the headlights being on. As I have been driving it for the past week. I only have issues on my way home. And by issues I mean some odd Idle miss's and the occasional hiccup in the idle cadence. But it has stopped stalling and is driving around very well.

Offline cudabob496

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Re: Idle just won't smooth out in gear
« Reply #8 on: December 12, 2014 - 09:12:35 AM »
old headlight wiring can draw a lot of juice, but your alternator may need replacing
with a higher quality model, that puts out the current at lower rpms.

also, you probably want to do the electrical bulkhead connectors bypass mod.  Its just
running a large wire from your alternator output to the 12V post on your starter solenoid.

http://board.moparts.org/ubbthreads/showflat.php?Number=7160026

http://www.madelectrical.com/electricaltech/amp-gauges.shtml
« Last Edit: December 12, 2014 - 02:34:17 PM by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline 734406pk

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Re: Idle just won't smooth out in gear
« Reply #9 on: December 12, 2014 - 10:39:58 PM »
You may need the carb cleaned and gaskets replaced. If you have ethanol in the fuel where you live, use a corrosion inhibitor like Stabil for ethanol at every fill up to reduce corrosion in your carb. This is a big problem in NY.
1973 Challenger 440 6 pack auto 3.91 rear
2012 Dodge Ram 3500 dually 6.7 Cummins Fleece EFI Live
1973 Challenger 318 2bbl auto 2.73 rear 22.5 mpg RIP
1970 Challenger TA 340 4bbl auto-Sold and sad
1999 Dodge Ram 3500 dually 5.9 Cummins Fleece tuned VGT-sold
1995 Kawasaki ZX1100E & still alive

Offline dodj

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Re: Idle just won't smooth out in gear
« Reply #10 on: December 13, 2014 - 08:15:40 AM »
I found the issue is directly linked to the headlights being on. As I have been driving it for the past week.
If that is true then you probably need to go through and clean all your connectors(with battery disconnected). Connector by the pass side valve cover, the bulkhead connector, ammeter connections, fusible link connector, starter solenoid connections, voltage regulator ground to firewall, engine to firewall ground strap, battery negative to rad support.
Doing the relay conversion for the h-lights would be a good thing to do as well if originality is not important to you.
Scott
1973 Challenger  440 4 spd 
2007.5 3500 6.7 Cummins Diesel, Anarchy tuned.
Good friends don't let friends do stupid things. ........alone.

Offline cudabob496

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Re: Idle just won't smooth out in gear
« Reply #11 on: December 13, 2014 - 08:31:12 AM »
If that is true then you probably need to go through and clean all your connectors(with battery disconnected). Connector by the pass side valve cover, the bulkhead connector, ammeter connections, fusible link connector, starter solenoid connections, voltage regulator ground to firewall, engine to firewall ground strap, battery negative to rad support.
Doing the relay conversion for the h-lights would be a good thing to do as well if originality is not important to you.

Ya, when I installed relays for my headlamps, the currect draw from my alternator went from 10 amps to 2 amps.  Plus,
I ran new larger wires to the headlamps.
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000