Re: 850 holly on a hemi
[Re: AndyF]
#2739178
02/02/20 09:30 PM
02/02/20 09:30 PM
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Joined: Jan 2004
Posts: 8,343 fredericksburg,va
cudaman1969
OP
master
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OP
master
Joined: Jan 2004
Posts: 8,343
fredericksburg,va
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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
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Re: 850 holly on a hemi
[Re: cudaman1969]
#2739303
02/03/20 11:49 AM
02/03/20 11:49 AM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
I Live Here
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I Live Here
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Posts: 19,318
State of confusion
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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.....
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: 850 holly on a hemi
[Re: A727Tflite]
#2739328
02/03/20 01:23 PM
02/03/20 01:23 PM
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Joined: Jan 2004
Posts: 8,343 fredericksburg,va
cudaman1969
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OP
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Joined: Jan 2004
Posts: 8,343
fredericksburg,va
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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. 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)
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Re: 850 holly on a hemi
[Re: hemi-itis]
#2739349
02/03/20 02:34 PM
02/03/20 02:34 PM
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Joined: Jan 2012
Posts: 2,678 Stuttgart, Arkansas
rickseeman
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master
Joined: Jan 2012
Posts: 2,678
Stuttgart, Arkansas
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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.
2011 Drag Pak Challenger
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Re: 850 holly on a hemi
[Re: rickseeman]
#2739351
02/03/20 02:42 PM
02/03/20 02:42 PM
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Joined: Jan 2012
Posts: 2,678 Stuttgart, Arkansas
rickseeman
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master
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Posts: 2,678
Stuttgart, Arkansas
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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.
Last edited by rickseeman; 02/03/20 02:42 PM.
2011 Drag Pak Challenger
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Re: 850 holly on a hemi
[Re: rickseeman]
#2739360
02/03/20 03:12 PM
02/03/20 03:12 PM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
I Live Here
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I Live Here
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Posts: 19,318
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Yep, and a bigger carb smooths out the frequencies making the motor much happier and less "peaky".....do it all the time.....
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: 850 holly on a hemi
[Re: rickseeman]
#2739411
02/03/20 07:44 PM
02/03/20 07:44 PM
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Joined: Aug 2003
Posts: 43,292 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,292
Bend,OR USA
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Last edited by Cab_Burge; 02/03/20 10:50 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 850 holly on a hemi
[Re: polyspheric]
#2739453
02/03/20 09:55 PM
02/03/20 09:55 PM
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Joined: May 2004
Posts: 12,416 Taxes & Virus's R-US, NY
Dragula
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I Live Here
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Taxes & Virus's R-US, NY
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All of the calculators do the same thing: allow you to not use your computer's calculator to do this: CFM = displacement × volumetric efficiency × peak power RPM ÷ 3,456
What it doesn't do: 1. allow for any manifold design except single plenum (the results for IR, divided single plane and dual plane will be completely wrong) 2. factor in manifold plenum volume (treats OEM low rise 273 manifold exactly the same as shoe-box tunnel ram) 3. factor in how nominal carburetor flow (what the manufacturer says) changes when it's not exactly the "right" size.
An 850 on that engine will flow more than 850. An 850 on a 273 will flow less than 850
All that yackin, and you didn't answer the OP's question.....lol...Care to add any experience with all the numbers?
Last edited by Dragula; 02/03/20 09:56 PM.
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Re: 850 holly on a hemi
[Re: cudaman1969]
#2739464
02/03/20 10:26 PM
02/03/20 10:26 PM
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Joined: Jan 2003
Posts: 12,256 Benton, IL.
DaveRS23
Special needs idiot
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Special needs idiot
Joined: Jan 2003
Posts: 12,256
Benton, IL.
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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.
Master, again and still
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Re: 850 holly on a hemi
[Re: Dragula]
#2739627
02/04/20 12:51 PM
02/04/20 12:51 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
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master
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Posts: 4,210
New York
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So, you didn't understand what I wrote?
Boffin Emeritus
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