High idle speed

[Rick Yasenchack]

My 1963 Cadillac with original carb, rebuilt professionally and finally adjusted to not stall at stops, but not idles to a point I can drive 25-30 mph with no gas pedal.

Nearing the end of a nightmare engine rebuild and would really love to drive before Ohio winter sets in.

I have adjusted the idle air and mixture screws per the shop manual, this makes very little if any difference.

My question, there was a copper plate at base of carb blocking the L-shaped ports in spacer.  This was removed by the engine installer.

I have seen many discussions about this, but cannot find. Is this plate/shim the problem?

Forgive me, I am not a mechanic, I do have a friend, whom is a mechanic and this has frustrated him.

HELP PLEEEEEEEEEEEEEASE

[Dennis P. DiBari]

Hi Rick,

     I have a 1964 2 Door Coupe - Series 62 with a 429 engine and a Delco Rochester carburetor.  There are 5 adjustments to my carburetor and I do each one very carefully.  The automatic choke is first and the butterfly is set to a crack, as I live in NY (Ohio is just as cold).  The fast idle cam is next and adjusted so it idles fast enough to open the choke fully.  The third and most important is the large idle screw at the rear of the carburetor.  If you have no reaction, then the vacuum hole controlling the idle is probably blocked by the wrong gasket!  If it is wrong, they used the FAST IDLE screw to set your idle and this is a big mistake.  Remove the carburetor and look at the gasket directly under the carburetor.  There must be a cut out in the gasket to allow vacuum into the hole to the large idle screw.  If blocked, it will never adjust.  Order a new gasket with the correct cut out.  Under the first gasket is the thick plastic spacer, and under the spacer is another felt gasket.  To adjust the large idle screw, the idle increases as you turn counterclockwise.  After you get the correct idle, then adjust the two front air/fuel mixture screws.  This is the proper order for a correct carburetor adjustment.  Let me know how you make out.  A lot of times, mechanics put a generic gasket under the carburetor (without the cut out) and use the fast idle screw for both - a big mistake.  Pull the carburetor - it is worth doing!

Dennis DiBari , NY