1967 Cadillac Calais choke

[richardbergquist]

How does the choke work on these? I suspect mine isn’t working as it’s hard to start when cold and when it does start it doesn’t have a higher rpm.

[67_Eldo]

Check the manual, page 6-72.

[richardbergquist]

I'm afraid I don't won the manual as of yet.

I have found that the vaccum clock closest to the firewall that when getting vaccum pulls a lever that will get the choke plate partially closed does not work properly. If it gets vacuum it will not effect the thing it is supposed to effect. I am not sure exactly what that thing does though, maybe offer partial choke under conditions when the engine is started warm.

[Julien Abrahams]

The choke is activated through the spring like action (due to the bi-metal) of the choke coil. You most likely have the choke with the choke coil on the heat stove on top of the intaje manifold. When cold, the choke coil pushes up and the choke plate closes as soon as you hit the accelerator pedal (when you get the manual, then check itpf you want to know why, it is explained well).
Via several small connecting rods, the choke llate closes almost completely. When the engine has started, the choke dashpot moves the choke plate to allow more air for smooth engine operation during warm up. As the engine heats up, the choke coil also heats up slowly pulling the choke coil rod down, opening the choke valve. When the engine has fully warmed up, the choke plate is vertical and it will unlock the secondary air valve via a tang that is pushed upward by the choke shaft lever. If theengine is still at high idle, the idle can be brought to "base idle speed" by tapping the accelerator pedal once. Again, for the details why this happens check the shop manual,pages 345 to 356 where the carburetor  operation is explained in detail. For me this was fun to read 😊.

[richardbergquist]

Thank you Julien! I will be very curious to read about it. I love complex functions that work on interdependence. The physiology of the human body has fascinated me much in my life and the leap to mechanical functions is actually quite logical. I will be getting the manual next week. And yes I have that kind of choke that you are talking about. My friend in Sweden who has a 1940 Dodge has a choke that looks very much the same. The reason that it’s hard to start might even be the fact that it has 87 in him right now; that is 87 AKI, roughly equivalent of 91 RON Octane that we have in Europe. When I receive the head cylinder and have replaced that I will fill up with 93 AKI. A shame that it’s 25-30 % more expensive though. In Sweden the difference from 95 RON and 98 RON is about 6 %.

[TJ Hopland]

The other thing you need to check is that there is still fuel in the carb when you go to start it.   A lot of q jets had issues with internal leaks letting the fuel leak out so you end up with a combination of a flooded engine and or no fuel in the carb when you go to start it.   Even if there are not leaks the heat soak when you shut down can boil the gas out of the carb.

To check things on a cold engine take the lid off the air cleaner or even remove the entire air cleaner housing to give you better access to stuff.    Choke should be open.   Try and position yourself so you can see down the throat of the carb where that gets difficult is you need both hands free so its easier said than done on a car this size.   The goal is to stick your finger in the choke to keep it open while with your other hand you operate the throttle lever.   When you operate the throttle the choke should try and close.   You want your finger in it to keep it open because you want to be looking down the throat for squirts of fuel.   Keep giving the throttle full strokes and observe how many squirts you get.  You should get at least 2 good squirts.   If you get nothing there is either no fuel in the carb or the accelerator pump isn't working.  When you remove your finger the choke should snap shut and more or less be locked shut if you poke at it again.

To see if its lack of fuel or the pump you can try pouring some fuel in it.    The big tube sticking up in the middle is the bowl vent so pouring some fuel down that tube will fill the bowl which is where the fuel is supposed to be.   If you put fuel there try the throttle lever again and see if it squirts.   If it doesn't you got a non working accelerator pump.  If it does squirt you either have leaks or heat soak issues.