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1947 Carburetor / Vacuum connections

Started by Jeff Trahan, November 20, 2014, 09:03:01 PM

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Jeff Trahan

I'm having trouble figuring out the carburetor / vacuum connections for my '47 and the manual isn't much help.  Getting ready to start the engine for the first time in over 50 years.  I had the engine rebuilt and all rebuilt components, including the carburetor (Carter WCD).  Unfortunately, gas spews out of multiple places on the carburetor when either the auxiliary electric fuel pump or the original fuel pump runs.  Maybe the float is sticking??  Maybe the gaskets are dried out from sitting for a year??  Maybe both??  One of the places the gas comes out is a port on the top left side of the carburetor (facing the engine from the front).  What connects to that port?  (Photo attached.)  I also have an unused connection on the bottom left side of the fuel/vacuum pump (again facing the engine from the front) that I think might be for the wipers but I'm not sure.  The bottom right port on the fuel/vacuum pump goes to the intake manifold and the bottom center port on the carburetor goes to the distributor vacuum advance.  Any help will be much appreciated.  Thanks.

Jeff Trahan
Jeff Trahan
#28564
1938 Cadillac V16 9033
1947 Cadillac 62 Convertible Coupe
1958 Cadillac Biarritz

harry s

Jeff, It looks like you are missing the overflow tube at the empty connection on top of the carb. I can't tell if the vacuum line from the carb to advance is there or not. Other things to check are as you mentioned the float and also the pressure of the electric fuel pump. It should not be more than  3 or 4 lbs. Good Luck,     Harry
Harry Scott 4195
1941 6733
1948 6267X
2011 DTS Platinum

Jeff Trahan

#2
What does the overflow tube from the top left of the carburetor connect to?

The port at the front center of the carburetor is connected to the distributor vacuum advance.  I'm pretty sure that is correct.

I don't think the electric fuel pump is causing the problem because the original stock mechanical fuel pump causes the same problem even when the electric pump is off.
Jeff Trahan
#28564
1938 Cadillac V16 9033
1947 Cadillac 62 Convertible Coupe
1958 Cadillac Biarritz

Bill Ingler #7799

#3
Jeff: Too add to what Harry has said, here are two pictures showing the route of the over flow line from the fitting on top of the carb. I second to what Harry has said and check the height of the float. If not set correctly or if the float is binding and preventing the needle valve from seating which stops the in coming fuel, then that would cause fuel to come out the overflow.  The connection on the left bottom side of the fuel pump is the vacuum line which goes up and goes back to the firewall for the wipers, radio antenna and windshield washers. Bill

Jeff Trahan

So is the overflow just dumping out on the side of the transmission below the accelerator pedal?
Jeff Trahan
#28564
1938 Cadillac V16 9033
1947 Cadillac 62 Convertible Coupe
1958 Cadillac Biarritz

Bill Ingler #7799

The routing across the back of the engine was done this way so if there was fuel from the carb then that fuel would be dumped away from the exhaust pipe which is on the right side of the chassis. If the float is set correctly then there should be no fuel coming out of this over flow line. Over flow line was designed as a safety issue just in case.   Bill

Smedly

Have you tried tapping the carb with a hammer. Some times when the float sticks the vibration of a hit will knock it loose. Hit it hard enough, but not so hard you break anything.
When a Doctor "saves a Life" it does not necessarily mean that that life will ever be the same as it was, but he still saved it. My 46 may not be as it was but it is still alive.
Sheldon Hay

Jeff Trahan

Thanks for all the help.  The hammer taps did the trick.  And now I know how to connect the overflow.
Jeff Trahan
#28564
1938 Cadillac V16 9033
1947 Cadillac 62 Convertible Coupe
1958 Cadillac Biarritz