carburetor tuning

I

iddie makel

Active Member
Hello everyone,
I've been reading the manual about carb tuning and have a question.If I start turning idle screws & making fast idle adjustments,what is the worse case scenario (other than the engine stopping) if I screw up the adjustment?? :eek:
Right now the Buick seems to be idling a little slow.It is not smoking.I have an old (DIXCO) engine analyzer but have not been able to get the engine speed up to the RPM stated in the manual(1200).Maybe I need to buy a modern analyzer,and maybe I'm just doing something wrong.I'm wondering if I should just leave it alone for now & worry about it when I rebuild the carb. :confused: As always,I am thanking you in advance for your thoughts.
iddie
 
iddie,
I dont know the exact year and model of your car, but 1200 rpm sounds kind of high for an idle speed to me. Most older American cars idled in the 500-700 rpm range.
 
Also, at 1200 rpm, you will not be able to make any adjustment with the idle adjustment screws. The idle circuit depends on the butterfly valves being close to closed to draw air around them to activate the circuit. At 1200 rpm your mixture should be controlled be the main metering system.
 
Hello BillK,& bob,
Thanks for the fast response.I'm sorry that I did not explain myself correctly.I was trying to refer to page 3-25 in my '55 shop manual paragraph 7 (a)"if carburetor is on engine,turn adjustment screw to obtain engine speed of 1200 RPM.see figure3-26).This is in reference to giving a throttle position of approx.20 MPH on level road.Sorry for the confusion.
iddie
 
hey iddie,
turning the idle screw shouldn't do any damage that wouldn't occur with stepping on the gas pedal. you should feel safe to get it up to the 1200 rpm, make your adjustments, and return it to the specified idle rpm.
 
Hello chub chub,
Thanks for the help.I'll play around with it.I just didn't want to mess up because it is running pretty smooth,and knowing me,I have the capability of "unsmoothing" it.
iddie
 
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