Re: Quadrajet Idle Mixture Adjustment
As stated,its very likely a retarded base timing issue causing the idle screw to be set higher then normal to obtain an idle which pushed the prim throttle blades past /out of the idle circut which will make the odle mix screws inactive.
Many marine motor have mild perfcams from factory so try 16-18 deg base timing and i bet the motor well be much happier there.
Adv the base timing will also make you have to decrease the idle enough to drop the prim throttle blades back down into the idle circut so the ildle mix screws will become active again.
If the dist has a vac adv also try hooking it to full intake vacuum all te time too.
Sobefore going nuts digging into the carb take a few mins to try doing the above suggested items which very well may fix the problem.
If not then go deeper into carb issues.
Let us know how you make out .
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)