Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2523366
07/18/18 12:14 AM
07/18/18 12:14 AM
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Joined: Feb 2005
Posts: 20,203 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,203
PA.
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Kinda explains why I like me my proform 850 so much. It may be flowing more than I think it is
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2523371
07/18/18 12:27 AM
07/18/18 12:27 AM
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Joined: Jan 2003
Posts: 11,728 Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,728
Portage,michigan
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Been known for a long time. Most small block guys jump from a 750 to a 950. The 850 is more commonly used on big blocks
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, low 10.30’s 1/4 1.41 best 60 foot 6.56 at 104.17
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2523373
07/18/18 12:39 AM
07/18/18 12:39 AM
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Joined: Dec 2014
Posts: 304 Florida
Mark Whitener
enthusiast
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enthusiast
Joined: Dec 2014
Posts: 304
Florida
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Flow tested a few carbs the other day, thought I'd share my findings. The Ultra HP carbs are the older design from around 2005 they are no longer sold.
Holley Ultra HP 750 part#80675 1.375 venturi / 1.687 base plate 819 cfm
Holley Ultra HP 950 part#80676 1.375 venturi / 1.75 base plate 825 cfm
Holley 850 "old style main body" part# 9380 Choke horn milled off, slabbed throttle shafts, annular boosters 1.58 venturi / 1.75 base plate 945 cfm
I'll be replacing the 1.375 main body of the 950 with a 1.45 main body and retesting in the coming weeks.
This test backed my suspicions about the true flow of the 950, as it was only able to make about 5 more HP than the 750 on an upper 500 HP 360 motor. 950 my ass lol, I know Holley took a lot of [censored] over that carb and the new XP950 has a 1.6 venturi because of it. Be aware that that new 950 with the 1.60 venturi is a poor choice. The entrance shape causes turbulence. I've had 3 on my flow bench, put every booster available in it. Flow and booster signal are down because of it, and I can get a 1.45 venturi Quick fuel to flow the same and have a much better booster signal. And you can hear the turbulence on the bench. Quick Fuel/Proform bodies are a much better choice, the entrance to the venturi is shaped better, as well as the new billet bodies from BLP and APD.
Mark Whitener [url=www.racingfuelsystems.com[/url]
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Re: Holley 750 vs 850 vs 950
[Re: Mark Whitener]
#2523376
07/18/18 12:47 AM
07/18/18 12:47 AM
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Joined: Jul 2012
Posts: 429 Washington
skrews
OP
mopar
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OP
mopar
Joined: Jul 2012
Posts: 429
Washington
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Flow tested a few carbs the other day, thought I'd share my findings. The Ultra HP carbs are the older design from around 2005 they are no longer sold.
Holley Ultra HP 750 part#80675 1.375 venturi / 1.687 base plate 819 cfm
Holley Ultra HP 950 part#80676 1.375 venturi / 1.75 base plate 825 cfm
Holley 850 "old style main body" part# 9380 Choke horn milled off, slabbed throttle shafts, annular boosters 1.58 venturi / 1.75 base plate 945 cfm
I'll be replacing the 1.375 main body of the 950 with a 1.45 main body and retesting in the coming weeks.
This test backed my suspicions about the true flow of the 950, as it was only able to make about 5 more HP than the 750 on an upper 500 HP 360 motor. 950 my ass lol, I know Holley took a lot of [censored] over that carb and the new XP950 has a 1.6 venturi because of it. Be aware that that new 950 with the 1.60 venturi is a poor choice. The entrance shape causes turbulence. I've had 3 on my flow bench, put every booster available in it. Flow and booster signal are down because of it, and I can get a 1.45 venturi Quick fuel to flow the same and have a much better booster signal. And you can hear the turbulence on the bench. Quick Fuel/Proform bodies are a much better choice, the entrance to the venturi is shaped better, as well as the new billet bodies from BLP and APD. I've heard that about the 950 XP. That's why I'm working with the 1.45 QFT main body. Should be a good match to my engine.
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Re: Holley 750 vs 850 vs 950
[Re: J_BODY]
#2523384
07/18/18 01:03 AM
07/18/18 01:03 AM
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Joined: Jul 2012
Posts: 429 Washington
skrews
OP
mopar
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OP
mopar
Joined: Jul 2012
Posts: 429
Washington
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wonder where my 1.48 venturi 1.79 would fall into that... Is that a Braswell ?
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2523456
07/18/18 09:19 AM
07/18/18 09:19 AM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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Carb companies would be better off just listing the venturi diameter and base plate diameter than giving us BS CFM ratings. back before the holley craze started in the mid-late '60's venturi and throttle bore sizes were the ratings. cfm ratings are bogus marketing tools.
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Re: Holley 750 vs 850 vs 950
[Re: justinp61]
#2523719
07/18/18 06:31 PM
07/18/18 06:31 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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FWIW, stuff I posted about 5 years ago: Carb ----------------------------------------------------------Dry Flow -- Calc'd Wet Holley 3310-2 "750" with choke ------------------------------ 796.6 ----- 732.9 Quick Fuel "950" 1.45 v body on Demon RS baseplate ----- 963.0 ----- 886.0 BG (Gold Claw / Demon RS) 1.425 venturi sleeve ---------- 958.1 ----- 881.5 BG (Gold Claw / Demon RS) 1.500 venturi sleeve --------- 1001.3 ----- 921.2 BG (Gold Claw / Demon RS) 1.562 venturi sleeve --------- 1012.0 ----- 931.0 Original thread LINK
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2524225
07/19/18 08:22 PM
07/19/18 08:22 PM
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Joined: Oct 2007
Posts: 4,213 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,213
New York
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And the question, relevant but never asked: "Are all of those tests done on the specific engine which develops that intake vacuum with that carburetor (no more, no less), or on the same fixture?
Please: be rude, I'm used to it.
Boffin Emeritus
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Re: Holley 750 vs 850 vs 950
[Re: polyspheric]
#2524226
07/19/18 08:36 PM
07/19/18 08:36 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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And the question, relevant but never asked: "Are all of those tests done on the specific engine which develops that intake vacuum with that carburetor (no more, no less), or on the same fixture?
Please: be rude, I'm used to it. It's a reasonable question with an obvious answer. It's also beyond my R&D budget to test them all in the manner you describe, interesting as the data might be.
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Re: Holley 750 vs 850 vs 950
[Re: skrews]
#2524521
07/20/18 01:40 PM
07/20/18 01:40 PM
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Joined: Oct 2007
Posts: 4,213 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,213
New York
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I apologize - not faulting your valuable work, thank you. Just pointing out that regardless of the rated vs. tested CFM a small engine won't pull enough vacuum to develop the rated CFM, and a big motor will run higher than the test vacuum (and more CFM), and perhaps enough to keep the low number PV closed...
Boffin Emeritus
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