Problem Running

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Jarvis

Jarvis

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First off,

I got this car in an effort to learn how to build cars. I have a 70 Dart /6. I can get the engine running (after some effort) but as soon as I let off the gas, the engine dies. We checked the gas pump and fuel filter and they are both allow gas to get to the carb. Any off the top of your head ideas from the gearheads? Also, I have the standard 5/8" sparkplug socket, and it is not grabbing the sparkplugs to remove and check them, and unusual socket required for this?

Thanks in advance,
 
You could check for vacuum leaks, pcv valve and system screwed up, etc.. try to wiggle the carb. It may be loose from intake or seperated itself. Some have screws inserted from bottom up.
Could be clogged idle jets in the carb if its been sitting a while. Old fuel turns to varnish like gunk in there. Just guesses.
There are different size plug sockets.
 
Try the 13/16 socket. That's what used to be pretty standard. Then they started using what we used to call "peanut plugs". LOL Sometimes it sucks to get old! Like redfish said, it's probably something plugged in the idle circuit or a vacuum leak. Mike
 
OK, I'm not the only slant 6 guy with this idling problem.

My newly acquired slant 6 70 DUster starts very easily(fuel must be right there) even in the cold Canadian winter up here, but then anytime you try and let it get down to any type of slower idle it stalls(or almost stalls, can be saved if you then hit the gas again and hold it at a very fast idle).

It has sat for a long time prior to my purchase so I might have some varnish issues. How do I get to the idle jets? Are they accessible near the mixture screw? WHat are the other parts of the idle circuit that might be clogged?

I know I also have a vacuum leak at the base of the carb so I'm fixing this tomorrow with a new $6 gasket. That will eliminate that issue.

Thanks for any help.
THe Big E
 
Slants can be very finicky, but if you start with the basics it can really help the troubleshooting process.
Basics include:
Timing = 5-10 BDTC - mine likes 8*
Valve lash adjustment = .10 intake .20 exhaust ( at operating temp )
Plugs = ngk zfr5n ( jeep cherokee plugs ) for spark plug tube heads
Plugs = NGK UR-4 for Peanut heads

additionally, Vacuum leaks in these areas:
Manifold to head mating surface
EGR valve if equipped
Throttle shaft ( especially if you are using a Carter BBD )
vacuum advance can at the dizzy
Brake booster if equipped
A/C system vacuum actuators
Heater hose valve.

Once all of that stuff is checked you will most likely have your issues resolved. Keep in mind that slants are very cold blooded and have bog/surge issues when cold so try to do all of the work (test/tune) while it's up to temp.

BigE, what carb are you using? If its a 2bbl carter I can help
 
My suggestion.

Take good pics of all the vacuum connections at the carb, then disconnect and plug ALL of them at the carb. This removes everything vacuum driven from the equation. See if the car runs as a stand alone. If it does, then you have a problem in the lines/equipment/parts beyond the carb.

Then hook up each system one by one. At some point if it starts to run bad, you found the system causing the issue.
 
I was having some of the same issue with my "new" car. Fist thing I done was gave it a basic tune up, plugs pionts. then i adjusted the idle screw in till the car stayed running on its own. Then I checked the timing. it was set at 32. once i got it down to 7 i readjusted the idle and checked the timing again. now i dont have the issue unless its cold. still need to adjust the air/fuel but that will be a later project. not good at that. I need a vacuum gauge first.
 
First off pre 75 motors (and some 74s) use the larger spark plugs and spark plug tubes with the 'O' rings. If your car is a 70 and does not have this setup and has 5/8th plugs its not a 70 motor! As for 'working' to get the car running and when it does dies at idle vacuum leaks might be some of the problem Most likely you have a Holley 1920 on the car, maybe a Holley 1945. Either carb can easily be rebuilt with a kit from Auto Zone for less than 25 bucks. Most likely this will be the biggest issue with your car. With the kit you also get a new carb to intake gasket. I am not a mechanic nor do I have the magic numbers by the book and I have set many a slant by my own formula to run with basic tools and it works for me.
Start with a thourough carb cleaning or a rebuild which I would do first. Turn the air/fuel mixture all the way in without any extra force when it bottoms out and turn it out 2 1/2 turns. New cap, rotor, points, wires, plugs, vacuum line from the distributor to carb, pcv hose from the pvc valve to the carb, pcv valve, and fuel filter. Gap the plugs at 35 with a feeler guage and gap the points at 16 with a feeler guage. All this can be done for under 100 bucks and if the motor is healthy this car should run like a Swiss Watch. Some tweaking on the timing may be needed if you made any adjustments. Just keep on the site with questions as there is a bunch of good people here with tons of slant knowledge. Good luck!!
Chas.
 
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