68 Starts, Idles rough then dies

[terenzim]

Had the car running great for a few weeks after putting the engine in the car. It's a 68 engine with a Weber carb conversion on it in a 72 MGB. All emmisions plugged and/or removed. All of a sudden it started driving like it was cutting out or starved of fuel intermittently. Engine starts, idles rough then dies and usually shoots a steam like mist back out of the carb when it dies. If you try to give it the slightest amount of throttle it acts like it's flooding or starving and dies. Idles from 1 to 5 minutes.
Here's what I did and the results:
Replaced fuel filter - no difference. Put a clear fuel line to the carb so I could see the fuel flow which was fine and clear.
Replaced fuel pump - no difference. Pump puts out a solid stream of gas.
Removed carb cleaned float bowl, blew out orifices. Floats working fine - no difference
Had carburetor rebuilt - no difference
Took fuel line from input side of pump and put it in a gas can of fresh gas to eliminate the tank or bad gas - no difference
Reset timing, was off about 10 degrees even though it was set correctly before - no difference. Noticed that timing light is not steady when engine runs.
Checked plugs and all are carboned up. Cleaned plugs - no difference
Checked and cleaned points. Checked dwell and are within limits. Rotor is not burnt - no difference
Replaced Coil. All connections on leads are fine. Battery connections fine. Engine ground wire fine. - no difference
Removed intake housing from engine and sealed with permatex to eliminate possibility of air leak - no difference

I'm open for suggestions.

[Flash75]

"All emmisions plugged and/or removed." Did you provide venting for the crankcase and the fuel tank when the emissions were removed? If not you need to be sure the gas tank and crankcase are vented. Weber, DCOE or DGV? Most people cannot tune a DCOE, takes lots of time and jets can be expensive. I would start with a complete engine tune up, including compression check and valve adjustment. Use an ohm-meter to check the resistance of all the plug wires, they should all have about the same resistance. Where is you distributor vacuum advance hooked? I would also change the rotor and condenser and get a new set of spark plugs. What kind of fuel pump do you have, what pressure? Use a timing light on each plug wire and note that each cylinder is firing based on the light flashing. Once the ignition and compression is known to be good you need to determine if the carb is running too rich, sounds like it is. I don't use a Weber but I remember some comments from others about the DGV requiring lots of ignition advance to eliminate stumbling.

Clifton

[terenzim]

The engine was running fine and no changes were made to the plugged/removed emissions. The fuel pump is from a 68 and is a known good pump. It pumps about a pint in 30 seconds. The carb is a 32/36 DGV and the distributor vacuum is hooked to the carburetor. I tried adjusting the mixture but it hasn't eliminated the problem. I'll try the complete engine tune up and repost the results probably Tuesday. Thanx.

Mike

[terenzim]

The complete engine tune up WORKED!!!!!! Thank you very much for the suggestion. Now all I have to do is tweak the vacuum advance and timing. I set the timing at about 12-14 degrees btdc and messed with the vacuum advance a bit, but at full throttle or high rpms I get some missing. For now I'm on the road. Thanks so much.

Mike

[terenzim]

**** New Update - see end of this post******* I'm back with more rough running issues. I've replace the points, condensor and rotor again. The car starts and idles great. When I take the car on the road and try to gradually increase speed/rpm to 2500-3500 rpm it starts to back fire in the carb. The carb, a webber, has been rebuilt. If I go full throttle the car accelerates without a problem and I could probably redline the car. If I want to maintain a speed in 3rd or 4th gear and ease back on the throttle the engine runs rough as if it's starving or fouling. Plugs are clean and burning good with good color. If at the cruising speed I push on the throttle just a little the car responds and then will maintain a speed until I ease off the throttle again. I've adjusted the valves and set the timing (12-14). I've set the mixture on the carb so that it idles the fastest then backed off 1/4 turn.
Looking for suggestions.

New Upate:
Due to a broken choke cable, I used a piece of wire and set the choke to somewhere between 3/4 closed and fully closed and after a 3 minute warmup the car runs great. I don't disconnect the wire at all. Could this be a mixture issue and if so which way am I, too lean or too rich?