Is a worked 850 big enough for an 485 cu in big cam Hemi or is a 4500 in the future?

You’ll definitely want the opinions of more experienced guys than me; but I’m gonna say an 850 - 4150 would be an extremely conservative choice for any 482” mill, especially a healthy Hemi. Would it run good? Sure. But I’m thinking there would be quite a bit left on the table as far as drag strip use. I run a 1000cfm 4150 (pretty similar to an 850) on my street/strip 451, and it runs great. 30 more cubes and the flow capabilities of a Hemi-head..... I would think a large 4500 would be in order.

Thanks,

Best out of the box carb we ever used on a Hemi of that size!

Proform 1050 in 4150 trim.....
https://www.jegs.com/i/Proform/778/67209/10002/-1

Vid to go with the one we ran.......

https://www.youtube.com/watch?v=mrm62S2Fmow

850 will work fine on the street. If you are going to race it and want to make max power then you'll need a good intake and a Dominator.

Thanks, I have a rat roaster with the standard two AFB top and a nice machined single four top, weighting my options here

We raced a 400 inch Hemi in A/SM back in the late 70’s with a Rat Roaster single four barrel and 850.

Every time we cracked the throttle the lid would deform from the vacuum.
Eventually cracked the lid.

Makes me think that carb was a little too small for that engine.
Went a 133 mph at 3400 pounds on 10.5” tire but we couldn’t get it to stick - only went 10.30’s.

Well that depends

http://4secondsflat.com/Carb_CFM_Calculator.htm

https://www.inchcalculator.com/carburetor-size-calculator/

Just google Carb CFM requirements

Everyone already knows this

I have bigger carbs on small blocks just sayin............No matter what anyone sez, I've been pitting Dommys on small and big blocks for years w/great results just go to my FB page and see for yourself.....

The lid I have was made from a 1-1/4 thick piece then milled inside to 3/8 thick. Feels very substantial, plus the bottom has 3 bolt bosses in the center that the lid could be attached also. Like I said the bottom was a later setup for the single four with the cast in dams. I have a milled 4150 carb that’s supposed to flow 900 but it wouldn’t work on my 499 Indy head engine, had to use a 4500 (7320)

I've never had a car yet that didn't run a whole lot faster using a carb bigger than the recommended. That's just my experience.

I had a 302 Maverick in high school. It ran best with an 800 Holley. (And you want to put an 850 on a 485 cu in Hemi?) 351 Cleveland Pro Stockers had 2 Dominators. I was at Sonny Leonards shop one day. He was dynoing an engine with EFI. (I know it's not carbs.) It had 7300 CFM throttle bodies on it. I said "Why so big?" He said because every time we put bigger throttle bodys on it we make more horsepower.

Yep, and a bigger carb smooths out the frequencies making the motor much happier and less "peaky".....do it all the time.....

Have a nice day

I've only work on Mopar race cars but all the motors from the early 331 C.I. hemi up to and including SB LA motors and B and RB as well as 426 Hemi motors have all ran faster at the tracks and made more power on a engine and chassis dyno testing with more air and fuel flow
Be careful on the fuel volume, you can run out of enough fuel to feed the bigger carbs making you think it isn't making more power with more air flow
if you can't enrichen the carbs fat enough to slow the car down in the 1/4 mile you don't have enough fuel delivery
Been there, done that way to many times
EDITED: That formula for CFM seems way to small for real world WOT drag racing results for max power

All that yackin, and you didn't answer the OP's question.....lol...Care to add any experience with all the numbers?

A lot of good replies already. My is also that every time I have added CFM to these larger engines, I have seen more HP.

Do you already have the 850? If so, or if you have access to an 850, why not strap it on and see how much vacuum it pulls at WOT? That would seem a good starting place to me.

Lacking any real engine specs or it's intended use, my first reaction is MORE CARB. 4500 all the way. But that's just me.

Thanks for all the reply’s so far, trying to get as much info to go in one direction. Never had a Hemi on the street before and looking for decent drivability with a four speed and 4.10 gears. I do like the looks-appeal of the AFBs. Single four top is for the 4500 so I’d have to use an adapter for the small carb. Has anyone had experience with the rat roaster and stock carbs?

So, you didn't understand what I wrote?