Greetings. '59 Laurentian has had carburetor intermittent oddness for the time that I've owned it - 4ish years. A couple of times, float has stuck (I think) as it began to run rough just after a cold start. Noticed fuel pouring down the carburetor from the gasket between bowl and air horn. A smack with a wrench and installation of a fire extinguisher under the dash has put that right.

More concerning and more frequently, it will momentarily run rough and sometimes stall when coming to a stop with clutch in. The more abrupt the stop, the more drastic the symptom.

Most problematic symptom - one can be cruising in any gear and letting foot off Accelerator with clutch out can set up sort of an oscillation, lurch lurch lurch. Looks like someone learning to drive standard for the first time.

Problem directly proportional to the movement of the car, or change in movement I suppose. 

I carefully disassembled carburetor, ultrasonically cleaned, blew out passages. Carefully reassembled with a high quality kit following '58, '59, '59-'60 manuals as well as instructions with the kit. Even with new needle and seat, float levels were spot on with no adjustments. 

Surgy buckle oddness remains although idle smoother and responds well to mixture adjustment.

Some research shows these were prone to warping and as a result both internal and external leaks.

Some specific examples with behavior similar to mine were attributed to this.

I am at a loss and welcome any thoughts, ideas, past experiences, etc.

*Sincere thanks*

Robert