Stutters and Stalls on Schedule

[Pathfinder]

1969 140/4: It seems every few weeks and after 150 miles or so of weekend/about town driving, the car seems to buck or shutter a little bit mostly at the lower rpm of each gear, with the exception of 4th. It does this for a few miles, then gets progessively worse, feels like its choking and then stalls out completely. Wait a few minutes, she'll start up again after a few tries, gun it through through the gears and a few stop signs and I can limp home. Wait a bit more, start it up on the 1st try, and she'll purr like a kitten and run again like nothing ever happened. 3rd time this summer, since June. Gas tank and lines were totally purged and the carbs were rebuilt in May. What the???

[91blaze]

Sounds similar to what mine did, it was a combination of bad timing and wore out throttle shafts.

[Jerry Whitt]

Another idea comes to mind. Between the carburetors and manifold is supposed to be a really thick gasket/spacer to prevent excess heat causing the fuel to boil.

The boiling fuel could cause the symptoms. If the spacer is missing, could cause these symptoms.

Another problem encountered is the fuel lines under the car on occasion, when parked over a very hot spot for a few minutes, will have the fuel actually vaporize, and then cause a no run condition called "vapor lock". When the fuel becomes a vapor hits the fuel pump, nothing happens, the car stumbles and stalls. Usually after sitting a while, it will restart.

[Pathfinder]

OK thanks for the info, I'll let you know how it pans out soon.
Phillip