cadillac eldorado 500 ci rough idle

[Thunderstroke]

Hi.
I have a 500 ci 1975 mod that will not start without me pressing the pedal, when it does start it has a very rough idlle and after a while it dies. Never had issues starting and driving it earlier and When I parked it the last winter it was no troubles at all, engine ran smooth and had no issues powerwise.
Any help with where I should start searching for any problem would be nice

ty

[V63]

#1, I would verify your fuel is FRESH if you come from an area where any alcohol is required to be added to the fuel. If you run the engine on stale fuel it can (and often does) seize the valves. Stale fuel does have a distinctive odor.

#2, Critters (rodents) will eat spark plug wires and vacuum hoses.

[76eldo]

Cars with carbs need a couple of pumps and when you depress the pedal it “sets” the choke and high idle.  Then the vacuum pull-off needs to open the choke plate slightly for some air to flow into the carb on full choke.

You may need a little work on the carb.

Brian

[Tony and Ginny 429]

Need to know that the complete tune up is on spec ( all new parts ) with vacuum advance working as it SB
Replace ignition wires if not done in a while

Check the choke for proper operation
Should be open 1/8 inch at first start up of the day
Only set choke when engine is cold before the days first start up each time

Once above is known to be on spec â€"if still a problem the carb might have to be rebuilt
If you feel any hesitation â€"-when you try to accelerate â€"the accelerator pump in the carb has gone bad  â€" So rebuild time for it

Enjoy