my dad's friend has a blown 383 with a 6-71 s/c....with 2 650 quick fuel carbs i think?
he's having a problem tuning them right and has called quick fuel's tech line just to talk to an idiot...not sure if he has called back yet to talk to someone else there...
i'm just trying to help since he painted my new front bumper on my s10 for me...lol
what he says it does is idle fine for 20 seconds then immediately runs rich, black smoke out the exhaust, and even leaves exhaust marks all over the ground...and he just can't tune it right...?
i think he said he had 66 size jets? big fuel line and big fuel pump...lol...not sure what size...and also he has plugged the power valves and/or unplugged them i don't know...sorry carbs are chinese to me...so nevermind my ignorance.
any help would be greatly appreciated.
Brian...hard to tune a carb if the ignition system is not up to snuff and the initial timing is off for the given application.Would be nice to know what is going on there.
The obvious comes to mind.The dual carbs have the float levels set correct,the pump pressure is regulated as to not overpower the needle and seat,the throttle plates are set as to not yank on the transition slots,the idle mixture screws are functioning and idle emulsified mix responds accordingly,low speed air bleeds are free and clear,bowl vents can breathe etc.
The main jet size and pv selection will have no effect on your idle a/f unless your yanking on the boosters.
At this point..I would take that 20 second window and get over the carbs and look for fuel pullover..beit boosters or discharge nozzles.If your not seeing raw fuel atop,suspect an internal leak path by a gasket.
To summarize..square off the transition slots and baseline the idle mixture screws 1/2 to 3/4 turn out off seat.This is a ballpark setting for a 2x4 application.If alls correct..you should be able to alter idle rpm and a/f ratio with mixture screw adjustments only.
Not a lot to go on with your limited info^..just food for thought for now.
Good luck and happy tuning.