<VV> New carbs - idle rough/ trash

[Louis C. Armer, Jr.]

Hey Pat, You need to suspect the carbs. Do you have equal
vaccum when you test the carbs with your hand over one then the
other? Whichever shows weak vaccum, WITH THE THROTTLE LINKAGES
DISENGAGED, should be inspected closely for a fuel blockage or vaccum
leak. Even brand new rebuilt carbs can get trash in them. Next, I would
reinstall regular points and condenser and see if the situation corrects.

Chuck Armer

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At 07:33 AM 4/16/04 -0500, you wrote:
>Got an issue I can't figure out. Rebuilt my 102 completely including
>professionally done carbs.
>
>Background:
>Had been breaking it in the last couple of weekends to get all the bugs
>worked out of it. The engine has nearly 300 miles on it, new pertronics
>ignitor one gapped per the instructions, new Clark's Magwire plug wires, NOS
>dist. cap and rotor, and the car is a powerglide and has single exhaust. The
>entire fuel system is new - tank, sender, hoses, clamps, fuel pump, etc. It
>also has an inline fuel filter. The entire wiring harnass is new. The only
>thing that is not new is the coil. It is a fairly new Crane that I had on my
>65 Turbo. It worked fine on that car and was only replaced because it was
>black and I wanted chrome.
>
>Issues:
>1) Cold blooded. When I try to start it, it will fire and die. I have to
>pump the pedal to keep it running. It takes a couple of minutes of this
>before it will idle without killing. Chokes are closed and the pull offs are
>new and operational. The Choke thermostats are strong and open fully when
>warm. The accelorator pump squirts a nice stream of gas like it is supposed
>to.
>
>2) Once warm the idle is rough and unacceptable. It jumps around quite a
>bit. Looking at my dwell/tach meter the idle changes 100 - 300 RPM
>inconsistently. I used a uni-sync to balance the carbs and they are
>identical in vacuum at idle. The linkage engages the carbs evenly. Pulling
>the linkage shows both carb butterflys starting to move at the same time.
>
>3) The idle mixture screw is set to 1 1/2 turns out. Moving the screw either
>way does not improve the rough idle. The fast idle cam is not contacting the
>tab once warm like it is supposed to.
>
>4) All Vacuum hoses are new and tight. The base insulators are new and the
>bolts securing the carb to the head are torqued correctly. The hoses to the
>balance tube have clamps attached. The vacuum at the modulator valve is
>strong and disconnecting the hose and plugging it does not change the rough
>idle.
>
>5) Disconnecting the vacuum advance and plugging it does not change the
>rough idle. The timing is set to 12 dgrs and with a timing light on the
>pully the mark does not bounce around with the idle.
>
>6) Once warm, I can run the throttle to about 1500 rpm, hold the linkage
>steady and the RPM's will fluctuate. I do feel a slight surge or pulsating
>at driving speeds.
>
>7) One interesting note - when balancing the carbs I initially placed my
>hand momentarily over the throat of the drivers side carb and all of a
>sudden the idle smoothed out. It ran smooth for a few minutes and all of a
>sudden it was rough again.
>
>If anyone has any suggestions on what to do next, please let me know.
>
>
>Pat Vanderlind
>62  Monza 900 cvt 102 PG
>65 Corsa 180 cpe
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Corvair Atlanta, BOD
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