ChrisP

ok these replies are helpful..bob do you think i can get the pieces out of the switch to clean them up WITHOUT removing the carb? i can see the screw that hold the switch in but I'm a little concerned about the vacuum piston and spring falling out if i pull the plunger out of the switch...i've heard it said that it's offen just a matter of cleaning up the contact inside

I think i've isolated a problem on the '48 S-11 custom to the kick down switch on the carb body. has anyone taken one of these out of the carb and attempted to service it? many thanks for any experiences anyone can share

Bernbaums does sell the dashpot plunger for the fluid drive cars, you have to ask them for it, it's not in the catalog

thanks for all the good suggestions guys....could be a simpler explanation: car was sitting around for 2 or 3 weeks with low fuel (dumb)....temp changes here in New England may have caused condensation in tank, because i filled up today and problem seems to have disappeared...may have been water in fuel? i'll keep an eye on it, many thanks again i learned some things...

So all of a sudden my 48 Desoto has developed a "stumble" that only seems to manifest itself when im driving in "high high" range....or 'fourth" on the fluid drive. That is what im observing: no prob in either low range gear, and "third" seems to provide good smooth acceleration...but in fourth, big time rough spot Car stumbles, hesitates, even wants to backfire. I know there is a second accelerator pump in the carb for the fluid drive...anyone able to shed some light on what this symptom might be? Vacume advance? Maybe im imagining it and need to drive it out to further observe but it seems like it's only demonstrating the problem in fourth Any ideas from the brain trust greatly appreciated CP