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Re: Carb size question
[Re: 68LAR]
#1567037
01/22/14 03:11 PM
01/22/14 03:11 PM
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Joined: Aug 2003
Posts: 43,215
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,215
Bend,OR USA
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I've never seen a 440 Mopar motor slow down at the track or loose power on the dyno by putting more air and fuel to it  Unless the guy doing the swap didn't know how to tune the carbs  One of my old race cars, 440 powered Duster that I bracket raced and ran in S/ST was used as a mule for carb size testing by me back in the early 1990s, I started it off with a Hollet 600 D.P. thinking the car would leave harder and react quicker with the smallert carb, back then NHRA Division 7 used the 4 tenths Pro Tree in S/ST and Pro bracket racing. I had bought a tranny with a trans brake in it so that was the reason to try and step up the reaction times. I put 4 or 5 carbs and two different intakes on the car by the end of that year, every time I put a bigger carb on it the car ran quicker and faster It picked up almost .8 ET and 7 or 8 MPH by going from the Hollet 600 D.P. on a TM7 intake to a Holley 1050 CFM Dominator List # 9375 on a Mopar M1 4500 intake My last mule motor, 526 C.I. Bracket race motor, liked the dual 1050 Holley Dominator carbs. a lot comparted to a single 1050 Dominator 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Carb size question
[Re: BradH]
#1567040
01/22/14 04:44 PM
01/22/14 04:44 PM
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Joined: Mar 2010
Posts: 341
Highland beach Fl
poisondart2
enthusiast
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enthusiast
Joined: Mar 2010
Posts: 341
Highland beach Fl
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Quote:
My experiences have been that you can get to the point where a bigger carb that makes more HP on the dyno actually goes slower than a smaller carb that's more responsive and has better shift recovery.
I've dropped from a Holley 1.562" v downleg carb to the original "950" HP w/ the 1.375" v downleg design and the car picked up .15 in 60-ft, .2 in ET and 2 MPH because the smaller carb simply ran better. Yet on the dyno, they showed virtually identical HP.
Plenty of people on here seem to "always" go faster w/ bigger carbs, but I'm not one of them.
Iam with you but got to say I believed bigger was better until I was talked into smaller by profesional carb builder. Now I just make a call have a carb built for any of my cars and dont question if I can go faster with a larger carb cause Iam no profesional. 
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Re: Carb size question
[Re: dynamite]
#1567042
01/22/14 07:41 PM
01/22/14 07:41 PM
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Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
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OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
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Do you guys think that maybe engine size and transmission type play into this question? Example, I have a stick car with a big block. On the street, I have enough torque to get moving without having to dip into the "go pedal" very much. At the track, I leave off of a 2 step and I'm usually into the secondary side of the carb at launch. With an automatic, unless you're leaving off of a trans brake, you're leaving off of the primary side of the carb at the track. On the street, I don't see much difference if you're running a big block. Small blocks usually make torq higher in the rpm range. Of course, cam and heads have something to do with all of this. Maybe I'm getting into the weeds too far on this subject. 
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
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Re: Carb size question
[Re: 68LAR]
#1567043
01/22/14 08:06 PM
01/22/14 08:06 PM
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Joined: Nov 2005
Posts: 690
New Hampshire, USA
oldiron
mopar
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mopar
Joined: Nov 2005
Posts: 690
New Hampshire, USA
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OK, here's a thought for you. At my last race at Atco, I was trying to slow my car down, to 10.0 I was running 9.95 to 9.98 lifting early in time trials. I got through the 1st round but had a much better light and passed the slower car by the 1/8th and lifted to just stay ahead and ran a 10.02. Being the idiot that I am, I backed the throttle cable so the secondaries opened about 1/2 way. 2nd round, I passed the car at about 1000' and lifted and did a 10.89 at 110. The 60' improved by .05 while the mph at the 1/8 was down by 2. So in my case, less carb was better (at least that day)
66 Belvedere Vert, 4 Speed/Jerico, slowly, very slowly, getting faster - NA LD Wedge New New Best: 10.56 @129 68 B'cuda 4 gear Jerico - Another New Best of 9.86 & Trying to slow up https://www.youtube.com/watch?v=T4jDLKwd9Gs
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Re: Carb size question
[Re: oldiron]
#1567044
01/22/14 08:18 PM
01/22/14 08:18 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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I dont know how much you drive your car on the street but I do drive mine alot and right now I use an 850 DP which along with the Indy dual plane it has great driveability. I can nail it at any rpm driving around and it is right there with instant responce. I feel I can go faster with a 1050 Dominator as when I put this eng together the eng just wanted more and more jet in this 850. So I found a happy spot where it runs good but is not to fat to foul plugs out driving on the street. I dont know if larger carb like a Dominator would have as good driveabilty on the street but I am pretty sure it would go faster at the track with a Dominator. But I am the kind of guy that when I find a good spot for jetting I leave it there for hot and cool weather driving as I dont feel like changing jets all the time. Last time at the track my brother-in-law said why dont I jet up some and try to go faster but I told him I dont want to because it drives so good with the jetting in it. I want to try a single plane and a Dominator one day and even if it goes faster if the driveabilty on the street is worse I may not leave it on. Ron
Last edited by 383man; 01/22/14 08:24 PM.
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Re: Carb size question
[Re: oldiron]
#1567045
01/22/14 08:22 PM
01/22/14 08:22 PM
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Joined: Jan 2014
Posts: 8
Southern Illinois
wedgedave
member
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member
Joined: Jan 2014
Posts: 8
Southern Illinois
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The last 2 years I have been running with the Victory Super Stock guys. I run SS/A so I cant run any faster than 10 Flat with 2- 750's on a Modman Indy manifold. With a 1080 dominator I have been 9.89 141.00 mph, so In some cases a bigger carb will help, it depends on what your trying to accomplish, Just want to run my numbers 10 flat.
Last edited by wedgedave; 01/22/14 08:25 PM.
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Re: Carb size question
[Re: dynamite]
#1567046
01/22/14 09:12 PM
01/22/14 09:12 PM
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Joined: Mar 2010
Posts: 341
Highland beach Fl
poisondart2
enthusiast
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enthusiast
Joined: Mar 2010
Posts: 341
Highland beach Fl
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Quote:
I lost .2 in going from a 750 Holley to 870 Holley..no other changes ,,just a carb swap at the track...
WOW That car is really good lookin.
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Re: Carb size question
[Re: oldiron]
#1567047
01/22/14 09:31 PM
01/22/14 09:31 PM
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Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
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OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
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Quote:
OK, here's a thought for you. At my last race at Atco, I was trying to slow my car down, to 10.0 I was running 9.95 to 9.98 lifting early in time trials. I got through the 1st round but had a much better light and passed the slower car by the 1/8th and lifted to just stay ahead and ran a 10.02. Being the idiot that I am, I backed the throttle cable so the secondaries opened about 1/2 way. 2nd round, I passed the car at about 1000' and lifted and did a 10.89 at 110. The 60' improved by .05 while the mph at the 1/8 was down by 2. So in my case, less carb was better (at least that day)
This had something to do with why I posted this. As you know when we race at National Trail, I have to slow down to an 11.50. I do have a smaller carb, but have never tested back to back with my 1050. when I did run this smaller carb, I also was running a different combo. I do plan on doing some track testing this spring with the smaller one for the NTR meet later this summer.
As far a street ability. My car has no issues. I wouldn't be afraid to get in it and drive across country. I'd run out of gas money before I got to the Mississippi, but it is what it is. Throttle response ... lets just say that from just above idle (1300rpm) with my foot off of the clutch, I can punch it and it will go sideways with ease. (This is the reason I use for not street racing anymore.)  
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
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Re: Carb size question
[Re: 68LAR]
#1567048
01/22/14 11:33 PM
01/22/14 11:33 PM
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Joined: Feb 2003
Posts: 1,942
Metro Detroit
OUTLAWD
top fuel
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top fuel
Joined: Feb 2003
Posts: 1,942
Metro Detroit
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Same day testing on the 493 that I have in my Plymouth
3310 holley 750 vac sec: 11.60 114.8
80496 Holley 950 HP: 11.44 116.5
when trying to knock it down to 12.0 at E-town (no roll bar, quite a while ago), had a mechanical throttle stop pulling more than half the travel out, still running high 11's
950 has good street manners, just drinks fuel!
Faster, Faster until the thrill of speed overcomes the fear of death...
71 Swinger - slowly collecting dust/parts
66 Belv. II - just a streetcar
88 Mustang - turbo LS beater
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Re: Carb size question
[Re: 68LAR]
#1567049
01/22/14 11:55 PM
01/22/14 11:55 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Quote:
Quote:
OK, here's a thought for you. At my last race at Atco, I was trying to slow my car down, to 10.0 I was running 9.95 to 9.98 lifting early in time trials. I got through the 1st round but had a much better light and passed the slower car by the 1/8th and lifted to just stay ahead and ran a 10.02. Being the idiot that I am, I backed the throttle cable so the secondaries opened about 1/2 way. 2nd round, I passed the car at about 1000' and lifted and did a 10.89 at 110. The 60' improved by .05 while the mph at the 1/8 was down by 2. So in my case, less carb was better (at least that day)
This had something to do with why I posted this. As you know when we race at National Trail, I have to slow down to an 11.50. I do have a smaller carb, but have never tested back to back with my 1050. when I did run this smaller carb, I also was running a different combo. I do plan on doing some track testing this spring with the smaller one for the NTR meet later this summer.
As far a street ability. My car has no issues. I wouldn't be afraid to get in it and drive across country. I'd run out of gas money before I got to the Mississippi, but it is what it is. Throttle response ... lets just say that from just above idle (1300rpm) with my foot off of the clutch, I can punch it and it will go sideways with ease. (This is the reason I use for not street racing anymore.)
Thats great that it has good driveability with the Dominator. What intake are you running ? Ron
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Re: Carb size question
[Re: 68LAR]
#1567051
01/23/14 01:32 AM
01/23/14 01:32 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Quote:
Quote:
Thats great that it has good driveability with the Dominator. What intake are you running ? Ron
Ron, No dominator. Quick Fuel Q 1050 AN on top of a Victor.
Larry
Oh I just assumed it was a Dominator. Thanks , Ron
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Re: Carb size question
[Re: 68LAR]
#1567052
01/23/14 05:59 PM
01/23/14 05:59 PM
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Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
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OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
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So what is the defining factor that determines what size carb to be used? From the replies, some have gone faster with a bigger carb, some have slowed down, some have gone faster with a smaller carb. Kind of confusing, but the question is still, what determines what size carb to be used? With so many different outcomes, maybe tuning is the answer, who knows? In the past, I've started with what has worked for other guys and moved on from there. (Trial and Error method)
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
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Re: Carb size question
[Re: 68LAR]
#1567053
01/23/14 06:55 PM
01/23/14 06:55 PM
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Joined: Mar 2009
Posts: 2,464
Sydney,Australia
tex013
top fuel
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top fuel
Joined: Mar 2009
Posts: 2,464
Sydney,Australia
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68LAR, my opinion is it not just putting more carb on it . It is a complete package with basic start line . My experience with my 440 with 8:1 ran 12.88-90 with a HP750 vac sec . But when I rebuilt it with more comp I went 825 mighty demon , this carb was good enough to finally crack a 10.99 with a lot of time spent tuning the car and motor, and some additional weight loss . I tried a dual quad modman , made the same peak rwhp , same mph but lost et due to a poor 60' .I back to backed the 825 to a HP1000 for maybe 3rwhp and maybe a couple of hundredths .When I put better flowing heads on I tried the 825 back to back to the hp1000(prosystem I had been trying)I picked up 28-29 rwhp .I have not tried the modman with these heads - yet . As you can see like you trial and error but the bigger carb will only inprove if the rest of the package will take benefit of the flow . For performance I would lean towards the 825 , QF 850 or Proform 850 as a starting carb ,then if I can borrow one try the hp1000 sized carbs - QF950 , Proform 950 by the way I did try a HP950 , 750 body 850 baseplate , at one stage it lost nearly 3/10's in the quarter Tex
New best ET 10.259@129.65 .
New best MPH 130.32
Finally fitted a solid cam,
stepped it up a bit more
3690lbs through the mufflers
New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm
Power by Tex's Automotive
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Re: Carb size question
[Re: tex013]
#1567054
01/23/14 07:43 PM
01/23/14 07:43 PM
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Joined: Oct 2003
Posts: 4,013
South Park, Pa.
68LAR
OP
master
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OP
master
Joined: Oct 2003
Posts: 4,013
South Park, Pa.
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Quote:
For performance I would lean towards the 825 , QF 850 or Proform 850 as a starting carb ,then if I can borrow one try the hp1000 sized carbs - QF950 , Proform 950
I'm currently running a Quick Fuel Q1050AN.. So you think I will go faster with a smaller carb????
Here's a thought. Isn't it true that a carb will only pass the quantity of air that the engine demands? If so, then putting a larger carb on and tuning it should be the answer and to slow a car down, put a smaller carb on so it can't pass the amount of air that the engine needs. After all, isn't an engine just an air pump? Just thinking out loud, maybe I'm completely out in left field here????????!!!!!!!
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
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Re: Carb size question
[Re: 68LAR]
#1567055
01/23/14 08:12 PM
01/23/14 08:12 PM
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Joined: Mar 2010
Posts: 341
Highland beach Fl
poisondart2
enthusiast
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enthusiast
Joined: Mar 2010
Posts: 341
Highland beach Fl
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Quote:
Quote:
For performance I would lean towards the 825 , QF 850 or Proform 850 as a starting carb ,then if I can borrow one try the hp1000 sized carbs - QF950 , Proform 950
I'm currently running a Quick Fuel Q1050AN.. So you think I will go faster with a smaller carb????
Here's a thought. Isn't it true that a carb will only pass the quantity of air that the engine demands? If so, then putting a larger carb on and tuning it should be the answer and to slow a car down, put a smaller carb on so it can't pass the amount of air that the engine needs. After all, isn't an engine just an air pump? Just thinking out loud, maybe I'm completely out in left field here????????!!!!!!!
Call a profesional carb builder as you are right but weight of the car heads cam headers trans rear all can be put into the equation
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