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| My Stumbling 72 Dart https://slantsix.org/forum/viewtopic.php?t=47875 |
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| Author: | Mr. Dart [ Sat Feb 11, 2012 8:18 am ] |
| Post subject: | My Stumbling 72 Dart |
Since owning this all stock 70,000 mile 72 Dart it has one irratating problem. The slant 6 has the holley 1920 1 bbl carb. The Carb. has been replace with a National Reman. and the distributor as well. Timing set to 2 & 1/2 degrees before TDC. Same problem. When you pull out--the bad stumble--once on the way runs good. The replacement carb. is the same type holley 1920 and the replacement dist. is stock with new Standard Blue streak points. Any help with this problem? |
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| Author: | neilskiw [ Sat Feb 11, 2012 8:25 am ] |
| Post subject: | |
First thing I would check is the accelerator pump adjustment on the carb. Some one on this site knows where to give you instructions on how to do it. |
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| Author: | SlantSixDan [ Sat Feb 11, 2012 9:51 am ] |
| Post subject: | |
Welcome on the board. Sounds like a nice car! I hope you kept the original carburetor rather than turning it in; "remanufactured" parts such as the carburetor and the distributor (why?) you installed have a very poor reputation—they almost never work well. If you did trade in the original parts, you are now on the hunt for a new distributor (easy) and a new carburetor (harder, though I may have one on the shelf; send me a PM). Tune-up parts and technique suggestions in this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. Make sure to check the valve adjustment . You will eventually want to convert to electronic ignition; it is enormously better in every respect. See HEI upgrade. |
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| Author: | Jester [ Sat Feb 11, 2012 11:24 am ] |
| Post subject: | |
Both '72 Darts I had with the 1920 carb on a 225 motor would do the annoying hesitation/stumble upon acceleration, unless I feathered the gas. Nothing I did would completely cure the problem, until I super-sixed the intake and added a Holley 2280 carb. Hesitation gone, problem solved. I don't like 1920 Holley's. From what I read on this site, they are either hit or miss. |
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| Author: | Aggressive Ted [ Sat Feb 11, 2012 11:39 am ] |
| Post subject: | |
Jester, You just need to keep the 1920 clean. That means running a good fuel filter, air filter and good gaskets to keep the economizer body free of debris, and replace the accelerator pump diaphragm making sure the linkage is good and snug. With 40 year old age they may not put out a pump shot like when they are new. I have about (4) 1920's now (different styles) and they all will spin both tires (with a 2.76 8 3/4" Sure-grip). They are great carbs, but with like anything, need maintenance. A few years back I found a 1920 sticking out of a coffee can full of water and pine needles under a tree. I cleaned the economizer body that was completely plugged from bad fuel that gummed it up and lots of aluminum oxidation from moisture sitting in it. Cleaned it all up and rebuilt the carb and it runs great! I ran it for two years after that. Hopefully Mr. Dart kept his original parts and will follow Dan's links and rebuild them. Re-manufactured carbs are just junk do the mix and match they do of the parts. Same with the distributors...many stick and will not advance correctly. |
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| Author: | neilskiw [ Sat Feb 11, 2012 6:25 pm ] |
| Post subject: | |
That's what I'm talkin' about! Technical Information !!!  Basically, from idle, when you crack the throttle- you let a bunch of air into the system. If the accelerator pump doesn't squirt in a volume of gas at the same time, the mixture leans out too much, and the engine stumbles. Take off the air cleaner (engine off), hold open the choke flap, shine a flash light down the throat of the carburetor, and activate the throttle linkage. Do you see fuel squirting? |
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| Author: | SlantSixDan [ Sat Feb 11, 2012 7:33 pm ] |
| Post subject: | |
Quote:
A few years back I found a 1920 sticking out of a coffee can full of water and pine needles under a tree. I cleaned the economizer body that was completely plugged from bad fuel that gummed it up and lots of aluminum oxidation from moisture sitting in it. Cleaned it all up and rebuilt the carb and it runs great! I ran it for two years after that.
That's terrific, but it's also nowhere near the usual reality, in which Holley 1920 carburetors definitely reach an end-of-life condition they cannot be brought back from without jacking up the idle mixture screw and installing a new carburetor around it, then installing a new idle mixture screw. It's important, especially with new posters who might be trying their hand at this hobby (or at least at this engine) for the first time, to make clear what the usual/likely scenarios are versus the unusual/jackpot types of happenings.
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