What setup (headers, etc.) do you have? What jets are installed? Is this the edelbrock 1813?
The 800's, especially the AVS, are calibrated very rich from the factory. If the PO of your car just ran it as-is out of the box, it will not run right on a stock 383. Too much fuel.
I run the 650 and the 800 AVS on a warm-ish 383 HP (headers, M1 intake, MP484 and 3000 stall). They are somewhat different designs and there are advantages for both. The 800 will work fine, but you will need the tuning kit for the carb and be prepared to spend some time tuning it as you cannot use the stock calibration. If you have access to a dyno or A/F gauge it will reduce the time considerably. You can tune it using just plugs and a vacuum gauge but you need to get jets installed that are in the ballpark. The stock primary jet is .113" which is too big. For reference, the 650AVS stock primary jet is .095"...which is too small for my 383 and I have to jet up. For the 800, I would start with .107" primary jets and work from there. Then you can adjust with metering rods & springs.
Another example of the differences: on the 650 I run larger secondary jets (4% richer on the edelbrock calibration graph for the 1806) to avoid lean stumble WOT. Using the 800, I have to use 4-8% leaner secondaries to avoid being too rich WOT. This is common for the 800 as the venturies are all the same size, whereas the 650 has small primaries.
My suggestion is to try and run what you have, for now. You will learn a lot in the process of tuning it. The manual, tuning kit, and the calibration graphs from edelbrock are all you need and dont cost much. Then if the results are not what you want, shop for a replacement. Short shifting around town and commuting, a 650cfm or less is ok. If you want to have some room to run high RPM, you can keep the 800 or pick up something like the new Street Demon 750. This is a nice carb because it combines all the features of the quadrajets, thermoquads, holleys and carters into one modern design.
