MY72BUG

This is a brief message for you but the end of a long and winding road for me.  Read on and you may save yourself a lot of grief when you find that your dual port does not want to idle.  I did a complete rebuild of my PICT 32 carburetor doing everything in a most meticulous manner.  The engine was done up with the top end, cylinders, pistons, rings given no end of attention.  When the project hit the road in 2003, that engine would do anything but find a smooth idle.  I reset every adjustment from three different books and always seemed so close but it would never give a steady consistent idle.  2004 saw me putter some more and it ran pretty good, even great at speed but never at idle.  I learned that the series of double holes in the throat of the carb venturi MUST be utterly clean especially the bottom set which provide your fuel at idle because unlike other carbs, the PICT idles with the throttle butterfly CLOSED tight.  Cleaning the bottom holes with an ultra fine dental pick got it working a little bit better but still NOT AT IDLE.  This year same old problem and I was getting ready to go for a whole new carb.  I knew it was fuel related.  One last look revealed something I had never noticed before.  That throttle plate has two semi-circular scallops on it.  My spare carb had them on the bottom of the plate.  Where were the ones on the troubled carb?  NOT VISIBLE until I looked down the throat of the carb.  Yes they were there!  Yes, during my rebuild I had installed the plate upside down!  Yes when the throttle plate was turned over and installed right two things happened.  1. the scallops fully exposed the bottom two holes in the venturi which allowed a steady supply of fuel  2. the air hole was moved to the other side of the venturi to allow the proper mixture of the fuel.  One more thing happened.  That old bug developed the smoothest, steadiest idle one has ever seen.  PLEASE learn from my mistake.   Dan Toombs

 

I'd rather have a partial bottle in front of me than a partial frontal lobotomy.
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Nice post Dan.  I have had my '67 rail with a 1600 engine in it since Sept. and it won't idle very well either.  I gave it a complete tune-up, plugs, wires, valve adj. cleaned the fuel tank, etc. and it still idles high at times and then very low wanting to die.  Is the plate basically the same from a PICT 32 to a PICT 34 (which I have)?  I guess I need to tear it apart and take a look. 

Thanks

  

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MY72BUG

Hmm.  I can't be sure as I have never had my hands on a Pict 34.  Remove the carb and look at it from the bottom.  Can you see two semi-circular scallop shaped indentations on the bottom of the brass accelerator butterfly?  Now, open the accelator wide open.  Can you see two scallop shaped indentations on the inside?  If they are on the inside they should be on the underside.  Turning the plate over will expose the idle holes in the wall of the venturi.  You will see a series of double holes all the way down the throat of the carb venturi.  All of these holes must be totally clean.  A bit of varnish or dirt will plug the fuel flow and ruin your idle.  The difference when I changed mine was like night and day.  Try setting your carb according to the methods shown in the various books.  I found subtle differences from one book to the next.  Make sure that all of the other possibilities are eliminated ie: anything to do with spark strength, timing, and compression.  Good luck.  Dan

I'd rather have a partial bottle in front of me than a partial frontal lobotomy.
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