IDLE TO HIGH

[CHUCK41]

     This is my first post, hope I get right   CLIFF you repaired a throttle plate for me about 2  months ago.
The carb is off a 73 Chevy pickup with a stock 350 engine. T he carb had 73 main jets and 44 main rods, the
rods were very bad, I had a new pair of 43s , I didn`t think it would hurt anything to use them. The P.V. spring
should open at 8in vacuum, the secondary rods are DA. With the timing at 8 btdc and the vacuum advance hooked
up the idle is 1000 rpm and 22in of vacuum, with the vacuum unhooked idle is 800rpm and 18in of vacuum.
With the vacuum hooked up I can cover the carb. with my hand and bring the idle down to 800rpm, any lower and
it dies. At 1000rpm I can put a little pressure on the secondary shaft and the idle will come down to 900rpm.
what do  need to do to get the idle down around 700rpm. this is a stock 350,std. trans. no air
              THANK YOU         CHUCK41

[Cliff Ruggles]

They didn't use manifold vacuum to the advance for most factory set-ups.  The correct port to the advance should be in the front of the main casting, drivers side, just to the right of the fuel filter housing.

Start there and re-set the idle mixture and speed screw.

If it still idles too fast, you may need to remove the baseplate, double check that all the throttle plates are fully closed, and see how much idle bypass air is being used.  If the plates are fine try blocking off the idle bypass air, this will allow you to lower the idle speed some.....Cliff

[429bbf]

just adding 2 cents  I'm not a chevy guy but i got great advice from this site . i had a stock 350 in a van and the timing stated 8 degrees . i advanced it to 12 according to chey guys on this site  and it ran a whole bunch better . moral of the post give it what it likes instead of whats stated on the tag is not always the best. fwiw

[CHUCK41]

  CLIFF  I may be able to get to the carb. this week, I have it off but have not been able to do anymore.
 
           I`M SORRY I DID NOT SAY HELLO TO EVERYONE ON MY FIRST POST, TALL ON THIS WEBSITE
            I SAY HELLO

   

[CHUCK41]

 
   CLIFF
       Went through the carb. again, made sure the float was set at 3/8, worked with the throttle valves to get
       them a little closer, blocked off the idle air bypass and set the  APT lower. have a very good idle at 700 rpm
       with 19 1/2 inches of vacuum, a 1/4 turn in or out will lower more then 50 rpm. The throttle will stick at 800
       rpm if I move it back to idle very slow but I`ll get it freed up.          THANK YOU         CHUCK41

[Cliff Ruggles]

Good news!