1932 Packard 900: Keeping it running...

1937 Buick 66C · June 3, 2018

Good day everyone,

I have been making significant progress on the 900 Roadster. After draining several gallons of shellac-like material from the fuel tank, replacing an old electric fuel pump that was full of goo, and rebuilding the mechanical fuel pump I have it running. but....

After initial startup the engine runs beautifully. It's quiet, smooth, has good oil pressure and stabilizes at 160F operating temperature. About the time it reaches operating temperature, something changes radically and the engine suddenly starves for fuel and stalls. It has exhibited this symptom each time I have fired it up. Given that the Detroit Lubricator 51 carburetor is the next item downstream in the fuel system, it is the prime suspect at this time. I removed the carburetor today, and have it on my workbench awaiting my next opportunity to spend a few hours working with it. Unfortunately, I been unable to find any technical information about these carburetors, and would appreciate some assistance from the collective wisdom from the forum.

When the Packard stalls when it warms up, it is a very deliberate stall. I cannot override the stall by vigorous feathering the throttle or by manipulating the choke.
In my mind it is as if there is a cold start fuel circuit that is thermostatically controlled and is operating properly. When the engine reaches a specific temperature the cold start circuit turns off; In my case the idle circuit is apparently blocked, therefore the engine starves of fuel as soon as the cold start circuit is no longer feeding fuel.
Is there some function in the Detroit Lubricator carburetor that does something like this? If yes, can someone on the forum please explain how this is works?
Is there any type of thermostatically controlled device in the intake manifold that would abruptly lean out the mixture after warm-up?
When I disassemble and clean this carburetor, is there anything that I should pay particular attention to?
I have determined that the is a two tiered adjustment on the bottom of the carburetor that appears to adjust the mixture. How does one go about adjusting this; Although I am quite familiar with various carburetors, I've never seen this type of adjustment.
Once I clean and reassemble the carburetor, where should the baseline adjustment be for initial restart?
I have also found a chrome knob on the right side of the distributor that permits the distributor to rotate about 20 degrees and lock into another predefined position. What is the intent of this rather unusual way to quickly change the ignition timing to a second preset position? Which position should it be set to (I'm at 5000' altitude).

I would appreciate any recommended contacts that any forum member might have regarding obtaining any technical documentation for this carburetor and distributor.

Thank you to everyone in advance...