Anyone running Stock 800cfm Qjets on their 350? I have "heard" some guys with built 350s like them. Just curious to hear your experience. Do you have to turn the idlemix screws way out to get a good idle? The idle air bypass allows a very small throttle idle setting, but it seems like you would need to set the mix screws way out to counteract all that air. The stock 800cfm units are jetted 73ish with 44 rods or thereabouts, seems like a good mix for a built 350ci. whats your combo and how does it work for you?
How about the idle bypass air? did you block it or leave it? what is your idle rpm? As I sit here and imagine, I tend to "think" a 350 could do fine without it.
ken, its one i had on the shelf. john and his buddy rebuilt it. stock as far as i know. the 350 has a cam in it. but its a stick. it idles nicely. the 650 holley works ok too.
I have ran the 71-74 800 cfm 455 carbs on the 350s from stock to wild with good luck. I used one built by John O with these specs: 0.74 primary jets 44 B primary rods Secondary Rods CV 0.054 All the carbs worked well with no issues, the best I have tried so far though are the 76-80 Buick 350 carbs that are also 800 cfm AND they have the APT feature.
The 76-80 350 Carbs may not have the bypass holes drilled. Look at the bottom of the baseplate and check this. The two grooved out ditches should have small holes at the very end of them. If not, drill them to .080 or up to .110 depending on the size of cam and vacuum it pulls. Pull the idle air/fuel screws and drill them to .090 or more straight thru AND from the top of the base plate. You may need to pull the idle tubes and enlarge them to .036-.037 and open the down channel to about .052. Then back off the idle screw on the drivers side of the carb. Fine tune until the carb idles without opening the throttle with this screw. This will achieve perfection on the idle circuit and avoid nozzle drip problems caused by turning the idle screw in. Mine is all the way off the throttle and I could throw it away I guess. The idea is to not use the throttle for idle assistance, Put all the air and fuel through the idle system. Get Cliff Ruggles book and see all the pictures and specs. There is more than I can put on here. but what I have noted so far gives you an idea as to what you can do to perfect this carb. You can modify an 800 carb for any size engine, but a stock 455 carb on a mild cammed 350 would probably be better than a stock 350 carb without any mods.
