Hi folks, is this a common thing with electric chokes? I've tried my best to illustrate in the pics as I'm no mechanic. Is it a fairly straightforward fix, or does this usually mean a new carb/rebuild? The car otherwise runs beautifully.


Also, with there being no temperature gauge (the only thing I don't like about the car), how warm do they normally get? From cold I can drive it half a mile and the hoses are too hot to touch, you can feel the heat resting your hand on the hood. But there is no steam, no hissing and other than a tiny drip from the radiator filler neck, no leaks whatsoever. Is there a way to tell if the radiator/water pump etc is doing its job properly? It's going in next week to have the system flushed and the thermostat replaced.


Thanks,
KiwiCadi

That vacuum device is called a vacuum break or pull-off and they are known to develope leaks and fail. Does it retract when the engine is started?
During cranking the choke is held closed by the tension of the thermostwtic spring. When the engine fires the engine vacuum will pull the vac break unit and bias the choke open to allow the engine to run.
These engine and carb arrangements are very sensitive to vacuum. Test both the vacuum pull offs with a small hand vac pump and replace as needed. After both vac pull-offs are known to work then the elcetric choke mechanism needs to be cleaned lubricated and adjusted.
You need to get the 1975 shop manual supplement. It addresses these details. Getting this function working correctly will save fuel and wear and tear on the engine internals.
As far as temperature goes, install a water temperature gage. The cooling system is the most overlooked of all systems. It needs to be drained, flushed with clear water and refilled every 24 months, regardless of mileage.
This care will protect the rad, heater core - nasty to replace, and freeze plugs in the block - another nasty.

when you say the hoses are too hot to touch, how hot does the radiator feel? If it is cool than the thermostat could not be opening... that would be the first thing I would change..

Hi guys, thanks for the replies.

drmenard: - The car's sat now for about an hour and a half, so probably not a good indicator now, but the radiator is definitely cooler to the touch than the hoses which are still warm (I should also add that its about 70F here too). It's getting flushed and the thermostat replaced next week.

blue_eldo: - The rod does not retract on the slide - I had it tied back with wire to keep the door open, but the car didn't like it when cold. Would replacing the choke pull-off assembly fix this? I have bought an aftermarket 2 inch water temp gauge, this will be installed when it goes in next week. It is also going to have the timing checked as it tends to pre-ignite.

The smog pump has been removed, as has the cat. The flexible tube on the left side exhaust manifold has been blocked off to stop hot air getting into the air cleaner carb etc.

Yes, replacing the choke pull-off would fix this.
You are going to have to look at the entire advance system in the dist. From sitting the mechanical adv tends to stick and the factory curve is not very good. Make sure it is free to move and springs back into position.
The combustion chambers tend to get carbon build-up that causes pinging. Look into using the GM top engine cleaner. If you get it to run cooler it will not ping as much either.
Plus the vac advance diaphragms are known to leak and not function.
Another aspect of these 500's, it all happens at low RPM below 3,300.