View Full Version : Rochester carb help

24-05-2004, 10:00 PM
Does anyone know anything about rochester 4 barrel carbs?

i rebuilt mine off my VL the other day, and had to remove a screw (with a spring underneath) next to the power piston. when i checked the manual while re-***embling it, it reads "this is set at the factory and will not rewuire adjustment", but where do i set it to? it seems to adjust where the needles sit when its idling, and sure enough theres way too much fuel coming in at idle! but as the w**** carb has to come apart to adjust this, i cant really tune it up properly.

(from memory this screw doesnt exist in the older quadrajets)

Does anyone know where to set it as a starting point?
theres a beer in it for you :D



05-02-2005, 05:00 PM
8) Contact Graeme at southern steering services in oak flats NSW he may be able to help u . He used to do dyno tuning & was an expert with rochestors & thermoquads. 02 42575502. Just ring & say u were talking to an avalanche owner online.

Generation Motorsport
12-07-2005, 03:50 PM
It sounds like the primarary mixture control piston, look at the top of the carby, and directly above where the piston is, there should be a alloy plug, drill a small **** into it, but not all the way, insert a screw, and pull the plug. You can buy a special tool to adjust it, or you can use needle nose pliers. start the eng, wind the idle screw up to about 1500 rpm, then adjust the piston as you would a mixture screw, to obtain the highest rpm. then fit the plug, adjust idle speed and mixtures. Setting it this way will give the car better fuel economy, power, and throttle response.
Hope this helps.
generation motorsport