On 09-25-97 TIM CAMPBELL wrote to ALL... 
 
 TC> Ok, I got the '40 LaSalle running and it runs great at low RPM's and 
 TC> when it 
 TC> is not fully warmed up.  I took it out for an extended run and after 
 TC> about 
 TC> 1/2 hour it really started to run rough.  I have new points, plugs, 
 TC> cap, 
 TC> rotor, etc. the carb was rebuilt, and I still don't have a clue. 
Vacuum/intake leak; as the [automatic?] choke comes open with 
warmup, the mixture gets too lean.  pull the vacuum advance line 
and light a cigarette; blow smoke into the the vacuum and look to 
see where it comes out. You might wanna remove the airfilter and 
use a rubber band & baggie to seal the carb throat. several hits. 
 
Izznt there a exhaust bypass that feeds hot gasses to bottom of 
the intake casting so as to prevent the cooling caused by the 
evaporation of gasoline from frosting up the intake.  Lots of 
times there is a leak between the exhaust and the intake which 
dont open up till it warms up some. 
 
Those intakes had a bimetal spring to open the hot exhaust to the 
baffle chamber, and they get corroded and hung up a lot. 
 
One other possibility: carb rebuild- the throttle plate shaft will 
often woller out the hole in the side of the carb over time, and 
then the open angle is no longer stable.  Competent rebuilders 
counter bore the throttle body and fit brass bushings to make 
the shaft rotate freely and true. disconnect the throttle return 
spring, and shake the shaft parallel with the air flow; rattle? 
  
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 * OFFLINE 1.58 * I went see Murphy for more law, but now he has alzheimers. 
--- Maximus 3.01
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