Fuel starve, or something Options

[arsprod]

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]

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?

[dr914@autoatlanta.com]

agree replace the condenser

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]

agree replace the condenser

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?

Really, condenser? Curious why

[Shivers]

agree replace the condenser

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?

Really, condenser? Curious why

.

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. confused24.gif

It was my first thought. Only because all that you mentioned happened in my 65 Tempest. I replaced the cap, the wires, the plugs and then the points. Still ran like (IMG:style_emoticons/default/stromberg.gif) An old guy I knew asked me if I replaced the condenser. A couple dollars after I threw so much money at it and it ran great. Should have with all the new parts. (IMG:style_emoticons/default/dry.gif)