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| Slant Six Stuttering and Stalling https://www.slantsix.org/forum/viewtopic.php?t=19291 |
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| Author: | DireRodent [ Mon Aug 21, 2006 5:49 pm ] |
| Post subject: | Slant Six Stuttering and Stalling |
I have a 1973 Dart with a 225 slant 6 and have been having problems with it for quite some time now. When it is started cold, it does not like to have the gas pedal touched much if at all because it tends to stall very easily. After it has warmed up, it only seems to try and stall if I am too aggressive on the gas, otherwise it can very slowly accelerate. If I try to push the gas much, even once it is warmed up, the car stutters and loses power - sometimes it backfires through the carb and then stalls, other times it will slowly rev through the stuttering and keep running, though in either case the thing is lethargic. What's worse is that all of these symptoms happen most of the time, but sometimes the car runs well enough. Any ideas anyone? |
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| Author: | Sam Powell [ Mon Aug 21, 2006 6:11 pm ] |
| Post subject: | |
There is a whole list of things to check. I will name a few, and other members will fill in the blanks. Check the choke, and see if it is closing when the engine is cold. See if the choke linkage is binding. It sounds like the carb needs to be replaced or rebuilt. The acceleration pump is liely not doing it's job, resulting in a very lean condition when you first open the throttle. Check the timing, and see if it is retarded. It should be set at least at 2 degrees advanced, and between 5 and 12 advanced will be better if you can advance it that far withougt having troubles with preignition. Unhook the vacuum advance when you check this. It should not make a difference, but will if it is hooked up to the wrong vacuum tap on the carb. |
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| Author: | Doctor Dodge [ Mon Aug 21, 2006 8:45 pm ] |
| Post subject: | |
It sounds like a lean condition and /or the lack of distributor advance. Check for the correct choke adjustment as already suggested. Also check the timing to be sure the initial is set to at least 6 degrees BTDC and that the mechaincal and vacuum advance systems are working. It would also be a good idea to check the valve lash and adjust as needed. DD |
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| Author: | DireRodent [ Tue Aug 22, 2006 1:48 am ] |
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I hope you'll pardon my ignorance, but what do you mean by checking to see if "the choke linkage is binding?" How would I find out if it is a lean condition and how would I check if there is a lack of distributor advance? I hope you'll have patience with me as I'm not exactly the most practiced of mechanics. |
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| Author: | Sam Powell [ Tue Aug 22, 2006 4:49 am ] |
| Post subject: | |
Your engine runs on a mixture of fuel and air that is blended in the carburetor. A lean condition is where there is not enough fuel compared to air. This can be from too much air, or not enough fuel. With the engine turned off, remove the air cleaner from the carburetor, and work the thriottle cable or rod (I don't know which you have) by hand a little bit. As yoiu open the throttle you should see a small stream of raw gas squirt down into the carb. This small stream is produced by the accelrator pump inside the carb. When they wear out, they will no longer put enough extra gas in to comensate for the sudden rush of air from opening the throttle, and the engine will stumble and falter. Sometimes the linkage to the accelerator pump is just gone altogether, and your symptoms sound like this to me. With the throttle open slightly, wriggle the round plate that is in the top opening of the carb. This is the choke. It is designed to close when the engine is cold, to limit the amount of oxygen rich molecules that are in cold air so the mixure does not become too "lean" with the oxygen rich cold air. If the choke is not free to close when the choke coil and rod pull on it, then it wil fail to close when the engine is cold and you will get way too much oxygen rich coldl air molecules for the engine to tun well. If both the choke, and the accelrator pump are not working you end up with an engine that runs pretty much as you describe your runs. Check to see if the choke linkage is hooked up. There is a rod that runs down to a bi-metal spring in a well in the exhaust manifold. When it is cold, this spring coils up and pulls on the ord, thus closing the choke. As the engine warms up, the coil relaxes, and the rod pushes the choke open. I may have the push and pull backwards here, but you be able to see which is which by examining the linkage, rod, and bellcrank on the end of the choke plate rod. If your carb has been either sitting for a long time, or if it has alot of miles on it, it might just be so gummed up or worn out, that it needs a complete ovehaul, or rebuild as they say. You can buy rebuilt ones at the better parts houses, but the rebuild jobs these days are not too great any more. It is really a skill you might want to learn yourself. Do a search on this forum for carb rebuilding tips. I'll let someone else explain how to time the engine. Guys, your on: Sam |
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| Author: | SlantSixDan [ Tue Aug 22, 2006 7:38 am ] |
| Post subject: | |
Howdy, DireRodent. Welcome onto the board. First step: Read and follow the instructions in this post. Buy the three books detailed there, read 'em, and you'll be much better able to tackle this problem with a minimal of difficulty and expense and maximum success. |
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| Author: | Doctor Dodge [ Tue Aug 22, 2006 8:02 am ] |
| Post subject: | |
The great thing about owning a SL6 is the fact that they are easy to work on and "forgiving", so time to jump in and learn how to get the engine to run better. Do your homework, read-up on the suggestions given and ask more questions as you go. Quote: I'll let someone else explain how to time the engine. Guys, your on...
Here are a couple of additional simple tests to do on the distributor:- Find the distributor and the small vaccuum hose coming off the vacuum advance pod. Use a clean piece of hose, connect it to the pod and suck on the it, to see if it holds vacuum. if it does not hold vacuum, it needs to be replaced. - Pop-off the distributor cap and grab the rotor, give it a light twist in the clockwise direction. You should feel some smooth movement, under spring tension. When you let go of the rotor, it should snap back to it's original position, this is your machanical advance system at work. For the actual timing checks while the car is running, you need a timing light, do you have one? DD |
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| Author: | DireRodent [ Wed Aug 23, 2006 1:40 am ] |
| Post subject: | |
Lots of great info and advice. I will do what I can as far as getting those books but it will probably have to wait a little while until the semester starts and I get some more money (college student). I'll get right on checking the choke and distributor stuff. I do have access to a timing light. I hooked it up and the car seemd to be right near if not on top dead center. For kicks and giggles, I decided to advance a little while it was running and the thing smoothed out quite a bit but because I didn't know what kind of effect it would have in the long run, I set it back to where it was. I appreciate all the responses you guys have given and how quickly. I'll do my best to keep you updated. |
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| Author: | Sam Powell [ Wed Aug 23, 2006 4:22 am ] |
| Post subject: | |
Go ahead and advance it at least to the first advance mark on the balancer. It will not hurt anything to do this. That should be 5 degrees on most balancers. Sam |
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| Author: | SlantSixDan [ Wed Aug 23, 2006 6:57 am ] |
| Post subject: | |
Yep, I agree with Sam. Advance it to about 5°. That means turning the distributor counterclockwise so that the timing mark moves "down" from the zero point. |
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