Ive got a 64 in my shop with an exhaust leak that at first listen seems to be under the carb or under the intake manifold. Sound like something common to anyone ? I use the hose from the shop vac to my ear to locate leaks and in the minute I spent on it thats where it seems to be.
Mark
The centre rail of the intake manifold is an exhaust gas passage. When your heat riser valve is closed on the driver's side hot exhaust gases pass under the carburetor to keep it from icing under cool humid conditions while the engine is warming up. A good culprit for the leak is a rusted choke tube as these are notorious for leaking as they become rusted making a ticking noise under the hood near the intake as you describe.
Dan's vote is the most likely as the rusted choke tubes are a common problem on these vehicles. The issue shows up in a variety of fashions from a puzzling sound like an exhaust leak to poor idling and difficult "cold" starts.
You can repair the choke tube if you prefer originality. Many opt to close it off and go with an electric choke. Repair and "close out" does require removing the intake manifold. It's also a good time to check the manifold for cracks since this is also occurs fairly frequently and is also a possible source for the noise you hear.
I was surprised to find a cracked manifold when my engine my rebuilt since the engine still idled and performed adequately. Since I live in a HOT climate and have little need for a choke, I replaced the manifold (which are getting hard to find), had the machine shop seal off the choke tube outlets, and continued with the use of an electric choke.
You can find pictures showing the location of the tube at:
http://6364cadillac.multiply.com/journal/item/9 (http://6364cadillac.multiply.com/journal/item/9)
A number of discussions concerning this issue can be found at:
http://autos.groups.yahoo.com/group/Cadillac_6364_club/messages/21081?threaded=1&m=e&var=1&tidx=1 (http://autos.groups.yahoo.com/group/Cadillac_6364_club/messages/21081?threaded=1&m=e&var=1&tidx=1)
http://autos.groups.yahoo.com/group/Cadillac_6364_club/messages/5817?threaded=1&m=e&var=1&tidx=1 (http://autos.groups.yahoo.com/group/Cadillac_6364_club/messages/5817?threaded=1&m=e&var=1&tidx=1)
http://autos.groups.yahoo.com/group/Cadillac_6364_club/messages/4551?threaded=1&m=e&var=1&tidx=1 (http://autos.groups.yahoo.com/group/Cadillac_6364_club/messages/4551?threaded=1&m=e&var=1&tidx=1)
HTH and good luck. Let us know what you discover.
Chris McBride
Cracked manifolds under the carb are pretty common. They will leak no matter the position of the heat riser valve. Depending on the size of the crack, it is possible to repair them using a common welding technique called "stitching" However, this procedure should be performed buy someone experienced in this method since doing it incorrectly can result in a bigger crack.
In any event, the manifold will have to be removed to ispect for the location and repair.
Mike