Moparts
Need advice on tuning my carb
Posted By: revcon
Need advice on tuning my carb - 04/20/10 07:42 PM
I have a new edelbrock 650 on a 383 in a dart. Starts fine, idles fine after choke goes off, but when the car comes up to operating temperature it stalls when in drive and stopped? I am not good with carbs, and don't want to start adjusting things without knowing. Could anyone direct me please? I have a stock fuel pump right now, does it need a high flow? Scott
Posted By: Lefty
Re: Need advice on tuning my carb - 04/20/10 07:44 PM
Have you tried raising the idle rpm?
Posted By: Dean_Kuzluzski
Re: Need advice on tuning my carb - 04/20/10 09:36 PM
It sounds like you're carb needs an insulator between it and the intake manifold or at least a sheetmetal heatshield. Those aluminum bodied AFB style carbs are prone to percolating when heat is transferred.
As far as a fuel pump, your problem is at idle, it doesn't take much to feed the motor at that time. It's a problem with the carb getting too hot or fuel mixture too lean, not a volume issue.
Posted By: revcon
Re: Need advice on tuning my carb - 04/21/10 01:24 AM
Ok. do you mean a ceramic spacer between the carb and manifold or insulation between the intake and valley pan like from the factory?
Posted By: dynamite
Re: Need advice on tuning my carb - 04/21/10 02:26 AM
I belive that insulation between the vally pan and intake is for sound deadining..to quiet the engine noise only..anybody else want to chime in on that..
Posted By: Dean_Kuzluzski
Re: Need advice on tuning my carb - 04/21/10 01:11 PM
Quote:
Ok. do you mean a ceramic spacer between the carb and manifold or insulation between the intake and valley pan like from the factory?
No, a phenolic resin spacer. It looks like a black piece of plastic. Or a sheetmetal heatshield.
Posted By: revcon
Re: Need advice on tuning my carb - 04/21/10 01:49 PM
Ok, Thanks. I will try that. Scott
Posted By: RapidRobert
Re: Need advice on tuning my carb - 04/21/10 02:50 PM
what is your idle speed, how many turns out are the mixture screws, when it dies see if the AP still has a good squirt, have some crank it at that time & see if the coil wire held 1/4" from ground has a nice blue spark
Posted By: Mr.Yuck
Re: Need advice on tuning my carb - 04/21/10 04:03 PM
1st up get it off the hot intake, especailly if you are using a factory iron unit. Next go get a vacuum gauge. Turn your screws in all the way then back them out 1 1/4 turn, Hook up the vacuum gauge and adjust for the best vacuum reading. Then reset your idle. Now take a timing light and set your timing. A mild 383 will probably like 36-38* at 2400rpm. See if that fixes your problem.
Posted By: revcon
Re: Need advice on tuning my carb - 04/21/10 05:17 PM
I have a MP aluminum intake. I will try the spacer. How thick should the spacer be? How much room is in a dart (68) with a stock 383 in it? Can a 1" spacer fit? After that I will check the other settings. I had to pour some gas in thecarb when the fuel pump was failing and it evaporated really fast, so I am thinking the carb is getting too hot as mentioned. What do the heat shields look like? How are they installed?
Posted By: Mr.Yuck
Re: Need advice on tuning my carb - 04/21/10 05:59 PM
I'd use a 4 hole 1/2" spacer. That should be enough. Make sure your choke flap isn't sucking shut when you drive.
Posted By: Dusted_Ya
Re: Need advice on tuning my carb - 04/21/10 10:08 PM
Ya kinda sounds like too rich maybe? The insulation between the intake and valley pan was for heat shielding not sound dampening...
Posted By: Dougsmopars
Re: Need advice on tuning my carb - 04/21/10 10:26 PM
Get the insulating gasket from edelbrock It works. Make sure your choke is fully open when it comes off fast idle. Adjust your idle setting. It doesn't sound from your description that it's a boil problem. Fuel in the bowl won't boil in the short time from start up to coming off fast idle. Usually fuel boiling becomes a problem after the motor has been running at operating temp for a period of time. 10 minuites isn't long enough to get the intake that hot that it will boil the fuel. Make sure your not running to lean. That will cause excessive heat.
Posted By: 383man
383man - 04/21/10 10:44 PM
Quote:
1st up get it off the hot intake, especailly if you are using a factory iron unit. Next go get a vacuum gauge. Turn your screws in all the way then back them out 1 1/4 turn, Hook up the vacuum gauge and adjust for the best vacuum reading. Then reset your idle. Now take a timing light and set your timing. A mild 383 will probably like 36-38* at 2400rpm. See if that fixes your problem.
Not trying to be smart but you should always adjust the carb last when tuning. You always set the timing before the final carb adjustment. 
Ron
Posted By: SixDRacing
Re: Need advice on tuning my carb - 04/22/10 02:42 AM
when you say it stalls, does it die? if so, how does it restart?
Posted By: Mr.Yuck
Re: 383man - 04/22/10 12:11 PM
Quote:
Quote:
1st up get it off the hot intake, especailly if you are using a factory iron unit. Next go get a vacuum gauge. Turn your screws in all the way then back them out 1 1/4 turn, Hook up the vacuum gauge and adjust for the best vacuum reading. Then reset your idle. Now take a timing light and set your timing. A mild 383 will probably like 36-38* at 2400rpm. See if that fixes your problem.
Not trying to be smart but you should always adjust the carb last when tuning. You always set the timing before the final carb adjustment. Ron
I do all that a few times Ron...lol I set timing, do the carb, set the timing tune the carb...So yeah you're right, timing 1st.
Posted By: revcon
carb - 04/22/10 05:55 PM
When I start it, it idles high until I press the pedal, then it goes to a nice idle. Once I drive around for 20-30 minutes and come to a stop, it stops running. It restarts by pushing the pedal to the floor and holding it. Then I have to put it in neutral when I stop and give it some gas. I have the carb lean/rich setting on the line for the setting in between the two. I had it two notches rich, and a friend said to cut it back to even. Maybe I will advance it one notch to see what happens after I install the spacer.??
Posted By: JAKE68
Re: carb - 04/22/10 06:08 PM
Quote:
When I start it, it idles high until I press the pedal, then it goes to a nice idle. Once I drive around for 20-30 minutes and come to a stop, it stops running. It restarts by pushing the pedal to the floor and holding it. Then I have to put it in neutral when I stop and give it some gas. I have the carb lean/rich setting on the line for the setting in between the two. I had it two notches rich, and a friend said to cut it back to even. Maybe I will advance it one notch to see what happens after I install the spacer.??
That adjustment you are refering to is the choke setting. It only affects cold starting. You have a problem after it is already warm. First when your car comes up to temp is your choke open all the way? If it is you need to set the 2 a/f screws in the front of carb for highest vacuum ready or highest smooth idle quality. If it does not then you need to work on why it isn't. If you still have a problem take it to someone that knows about that stuff. All the knowledge in the world on this sight can't help if you do not understand what they are talking about.
Quote:
All the knowledge in the world on this sight can't help if you do not understand what they are talking about.
Agreed. Now that we have more info............
it sounds like either a vacuum leak or an extreme lean condition due to the lack of tuning.
Posted By: revcon
Re: carb - 04/23/10 01:53 AM
I will admit I don't know much about Carbs, except consuming them. The information is all excellent, and I want to learn how to take care of the car myself. THANK YOU!
Now the vacuume was plugged when the car was assembled, and I was told it wasn't needed? Do I need to open that up and connect it? might that be the problem? I ordered the carb spacer.
Posted By: JAKE68
Re: carb - 04/23/10 12:06 PM
What vacuum are you talking about???????Dose not make sence. Did you check the things that i mentioned? You have to find the source of your problem before trying to cover it up with a spacer. Belive me the spacer is not your problem. I have thousands of cars i have worked on that do not have a spacer and they run fine. It did not come with one from the factory. It ran before so it has to run again.
Posted By: Mr.Yuck
Re: carb - 04/23/10 12:30 PM
Quote:
I will admit I don't know much about Carbs, except consuming them. The information is all excellent, and I want to learn how to take care of the car myself. THANK YOU!
Now the vacuume was plugged when the car was assembled, and I was told it wasn't needed? Do I need to open that up and connect it? might that be the problem? I ordered the carb spacer.
I'm guessing your vacuum advance is plugged? While it's not always best to do that, it is not going to cause the problem you have. The Vac advance is run from a port on the carb to the distrib. Do yourself a hug favor and go get a manual and start reading the "tune-up" section.
Posted By: gtx69
Re: carb - 04/23/10 12:49 PM
Well Jake does know what to do.He just got me running good on this six pack.Hats off to Jakes and his crew
