Fuel starve, or something |
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Fuel starve, or something |
arsprod |
Jul 26 2024, 02:56 PM
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#1
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Member Group: Members Posts: 210 Joined: 14-March 15 From: Indianapolis Member No.: 18,519 Region Association: Upper MidWest |
Teeners,
I swapped out the single carb that came with my 74 2.0 for new to me dual Weber 40's. It took a bit to get them jetted and adjusted but it's at least very close. The car runs great - and then it doesn't. With no consistency, it will start to stumble, cough, and backfire. Most of the time it works itself out though seems to be getting worse. I'm befuddled. (IMG:style_emoticons/default/confused24.gif) Here's what I know: - carbs are jetted main 145, air 200, idle 65, venturi 28 - plugs look ok, if anything rich - I don't seem to have any vacuum leaks - steady 3psi fuel pressure - timing and valves adjusted - new plugs Help! thanks Aaron |
Superhawk996 |
Jul 26 2024, 03:45 PM
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#2
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914 Guru Group: Members Posts: 6,469 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
Sounds more like an ignition issue because of the randomness. Could be sticking advance plate assuming you’re using a traditional mechanical distributor.
Ignition and fuel issues are commonly mis-diagnosed one for the other. Otherwise not enough info in your post to be of much help. No mention if RPM’s and load when this occurs. No photos of plugs. Have you verified bowls are clean and free of debris? Checked the jets for debris / corrosion? The jetting you have is a little bit non traditional (main smaller, idle larger) but should be capable of running consistently and reliably. On the fuel side, are you sure you have carbs properly tuned for best lean idle and synchronized properly? |
arsprod |
Jul 26 2024, 05:17 PM
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#3
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Member Group: Members Posts: 210 Joined: 14-March 15 From: Indianapolis Member No.: 18,519 Region Association: Upper MidWest |
Sounds more like an ignition issue because of the randomness. Could be sticking advance plate assuming you’re using a traditional mechanical distributor. Ignition and fuel issues are commonly mis-diagnosed one for the other. Otherwise not enough info in your post to be of much help. No mention if RPM’s and load when this occurs. No photos of plugs. Have you verified bowls are clean and free of debris? Checked the jets for debris / corrosion? The jetting you have is a little bit non traditional (main smaller, idle larger) but should be capable of running consistently and reliably. On the fuel side, are you sure you have carbs properly tuned for best lean idle and synchronized properly? I know jetting is weird but ended up there after trial and error. I feel comfortable saying they're at least very close to tuned. It's worse under load above 3k rpm. I'll pull the bowls again and check. Interesting theory about ignition. It's an 009 that came with the car. |
Artfrombama |
Jul 26 2024, 06:19 PM
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#4
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Member Group: Members Posts: 156 Joined: 21-January 24 From: Alabama Member No.: 27,870 Region Association: South East States |
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