Jet Size starting point
 

Could someone please give me a starting point on which jet's to use with a 850cfm on a 468 big block.

Is the carb new? If so, start with what it came with. If not, look up the specs for it and compare to what it has in it. To get a better idea of what it might need you need to give a lot more info on your combo, intended use, etc.

It is not a new carb. It is a BG that came on a big block running nitrous. I just want to get it in the ball park

Start with 80's on all corners and work from there. If the power valves are blocked then step up 2 sizes larger then go from there :!: :!: 80's are stock in a 850 holley :!: :!:

Mark

80 with PV's, 88's with the PV's plugged will be a safer starting point. Put .026 restrictors in the main air bleeds. Once you get it running and get jetting close there are some emulsion changes you can make that will help, but to start this will get you running.

Thanks for the help.