Previous Thread
Next Thread
Print Thread
Page 2 of 2 1 2
Re: You guys were right about the bigger carb [Re: justinp61] #1909916
09/10/15 02:07 PM
09/10/15 02:07 PM
Joined: Jan 2003
Posts: 11,701
Portage,michigan
B
B3422W5 Offline OP
I Live Here
B3422W5  Offline OP
I Live Here
B

Joined: Jan 2003
Posts: 11,701
Portage,michigan
Originally Posted By justinp61
How much HP does the 323 make? You can't make HP without air and fuel regardless of CI.


The dyno said 475, but that was without the accessories I am running on it.


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, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8

Re: You guys were right about the bigger carb [Re: Monte_Smith] #1909974
09/10/15 03:18 PM
09/10/15 03:18 PM
Joined: Aug 2003
Posts: 3,245
Between a rock & a hard place
C
cudadoug Offline
master
cudadoug  Offline
master
C

Joined: Aug 2003
Posts: 3,245
Between a rock & a hard place
Originally Posted By Monte_Smith
Not surprising at all. You seemed to be basing your 750 choice by stating "it's only a 318". The size of motor was irrelevant. It made X HP and that HP needs some air flow. The small venturi of the 750, at least in my mind is way too small for about anything that makes decent power, regardless of inches


I think many (I know I have!) fallen under that assumption.

Re: You guys were right about the bigger carb [Re: cudadoug] #1909988
09/10/15 03:39 PM
09/10/15 03:39 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Originally Posted By cudadoug
Originally Posted By Monte_Smith
Not surprising at all. You seemed to be basing your 750 choice by stating "it's only a 318". The size of motor was irrelevant. It made X HP and that HP needs some air flow. The small venturi of the 750, at least in my mind is way too small for about anything that makes decent power, regardless of inches


I think many (I know I have!) fallen under that assumption.


I had a 1050 dom on a 405ci... but just think of the
old pro stock truck engines.. a SB with 2 doms sitting
on the top.. I dont remember the ci on them but they were
SB engines.... every time I put a larger carb on I went
quicker and faster... I was gonna try a 1150 dom but I ended
up selling the engine
wave

Re: You guys were right about the bigger carb [Re: MR_P_BODY] #1909993
09/10/15 03:44 PM
09/10/15 03:44 PM
Joined: Jul 2004
Posts: 19,317
State of confusion
T
Thumperdart Offline
I Live Here
Thumperdart  Offline
I Live Here
T

Joined: Jul 2004
Posts: 19,317
State of confusion
The bigger carbs work even better if you spin em higher and that`s probably why the twin dommies worked so well on the old pro-stocks.......


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.....
Re: You guys were right about the bigger carb [Re: B3422W5] #1910027
09/10/15 04:55 PM
09/10/15 04:55 PM
Joined: Nov 2004
Posts: 6,890
North Alabama
M
Monte_Smith Offline
master
Monte_Smith  Offline
master
M

Joined: Nov 2004
Posts: 6,890
North Alabama
All a carb guy can do is tailor the fuel curve.......can't make it pass more air. As long as the carb will maintain signal and air speed, you are not really going to "over carb" a motor. If it felt "sharper" down low with the smaller carb, that tells you the 950 is likely a bit rich down low, but that's easily fixed.

Last edited by Monte_Smith; 09/10/15 04:57 PM.
Re: You guys were right about the bigger carb [Re: B3422W5] #1910098
09/10/15 07:32 PM
09/10/15 07:32 PM
Joined: Jan 2003
Posts: 30,947
Oregon
A
AndyF Offline
I Win
AndyF  Offline
I Win
A

Joined: Jan 2003
Posts: 30,947
Oregon
Originally Posted By B3422W5
Originally Posted By justinp61
How much HP does the 323 make? You can't make HP without air and fuel regardless of CI.


The dyno said 475, but that was without the accessories I am running on it.


A 650 carb will feed 475 hp. If you have that engine on a dyno with a mass air flow setup I bet it isn't using more than 650 cfm. That tells me that something was wrong with your 750 carb.

Re: You guys were right about the bigger carb [Re: AndyF] #1910100
09/10/15 07:44 PM
09/10/15 07:44 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Originally Posted By AndyF
Originally Posted By B3422W5
Originally Posted By justinp61
How much HP does the 323 make? You can't make HP without air and fuel regardless of CI.


The dyno said 475, but that was without the accessories I am running on it.


A 650 carb will feed 475 hp. If you have that engine on a dyno with a mass air flow setup I bet it isn't using more than 650 cfm. That tells me that something was wrong with your 750 carb.


You have to look at RPM also.. as the RPM goes up you need
to move more air... I use my header program to figure the
air flow at max RPM... its the same program you use Andy
wave

Re: You guys were right about the bigger carb [Re: B3422W5] #1910279
09/10/15 11:14 PM
09/10/15 11:14 PM
Joined: Jan 2003
Posts: 30,947
Oregon
A
AndyF Offline
I Win
AndyF  Offline
I Win
A

Joined: Jan 2003
Posts: 30,947
Oregon
CID x RPM x VE gets you the same basic number as using HP for carb sizing.

323 cubes at 6500 rpm only needs about 650 cfm. So something was wrong with the 750 carb. A properly built 650 carb on that engine would make more torque and go down the track faster than the 850 that is on there now.

Re: You guys were right about the bigger carb [Re: AndyF] #1910285
09/10/15 11:19 PM
09/10/15 11:19 PM
Joined: Jul 2004
Posts: 19,317
State of confusion
T
Thumperdart Offline
I Live Here
Thumperdart  Offline
I Live Here
T

Joined: Jul 2004
Posts: 19,317
State of confusion
Originally Posted By AndyF
CID x RPM x VE gets you the same basic number as using HP for carb sizing.

323 cubes at 6500 rpm only needs about 650 cfm. So something was wrong with the 750 carb. A properly built 650 carb on that engine would make more torque and go down the track faster than the 850 that is on there now.


How bout a friendly challenge Andy......you build the 650 and I`ll do the 850 and see which is faster. We all could learn some stuff here...... shruggy I thought it was a 950 though which will still work. thumbs

Last edited by Thumperdart; 09/10/15 11:20 PM.

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.....
Re: You guys were right about the bigger carb [Re: AndyF] #1910294
09/10/15 11:48 PM
09/10/15 11:48 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Originally Posted By AndyF
CID x RPM x VE gets you the same basic number as using HP for carb sizing.

323 cubes at 6500 rpm only needs about 650 cfm. So something was wrong with the 750 carb. A properly built 650 carb on that engine would make more torque and go down the track faster than the 850 that is on there now.


I never agreed with that formula... a 1050 dom
would be way to big on my 405.. yet every carb
that was bigger went quicker/faster
wave

Re: You guys were right about the bigger carb [Re: B3422W5] #1910376
09/11/15 02:23 AM
09/11/15 02:23 AM
Joined: Nov 2004
Posts: 6,890
North Alabama
M
Monte_Smith Offline
master
Monte_Smith  Offline
master
M

Joined: Nov 2004
Posts: 6,890
North Alabama
I don't agree with that formula either. Doesn't seem like it would matter what the cubic inches are. To make power, you need a certain amount of air flow. And as we all know......what works best on the dyno, many times is NOT the best for making the car run at the track

Re: You guys were right about the bigger carb [Re: B3422W5] #1910377
09/11/15 02:28 AM
09/11/15 02:28 AM
Joined: Jan 2003
Posts: 11,701
Portage,michigan
B
B3422W5 Offline OP
I Live Here
B3422W5  Offline OP
I Live Here
B

Joined: Jan 2003
Posts: 11,701
Portage,michigan
Car has a 950 proform on it currently, jetted 86/92.
I tried a new proform 750, jetted 78/84. With this carb the car was slower in all incrementals, including 60 foot. Seemed lazy, throttle not as crisp, didn't rev as quick.
Best ET with 750 was 12.11. Same night 950 went 11.91. About 3 mph less with 750
Has been 11.79 with the 950 in much better air. Will race it this weekend in good air.
I frankly don't get it.
My little brother has an old 750 Holley of mine on his 360 motor, about 10 to 1. Eddie heads, single plane, flat tappet cam. Roughly same weight as mine, has been 11.30's with the 750. Makes me wonder what it might run with my 950 on it............

Last edited by B3422W5; 09/11/15 02:46 AM.

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, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8

Re: You guys were right about the bigger carb [Re: Monte_Smith] #1910380
09/11/15 02:36 AM
09/11/15 02:36 AM
Joined: Jan 2003
Posts: 11,701
Portage,michigan
B
B3422W5 Offline OP
I Live Here
B3422W5  Offline OP
I Live Here
B

Joined: Jan 2003
Posts: 11,701
Portage,michigan
Originally Posted By Monte_Smith
I don't agree with that formula either. Doesn't seem like it would matter what the cubic inches are. To make power, you need a certain amount of air flow. And as we all know......what works best on the dyno, many times is NOT the best for making the car run at the track


Interestingly, at the engine masters challenge this motor was run with a Holley 950hp on it, which it belted out 477 with. The guy who built the motor is mighty intelligent, but the motor wasn't going down the track on those dyno pulls.
I suspected( and several knowledgable friends of mine agreed) that the car might 60 foot better with a smaller carb on it, and not lose elsewhere with a smaller carb for a net gain.

Thus far, that provably has yet to be the case. Even in the worst air the car has ever been in, it 60 footed it's best ever( this last outing). I have tried timing, next is to play with jetting on this 950. Probably yank 4 out front and back tomorrow after a test pass as it currently is set up, and see what happens. 86/92. HAS to be more jet than I need. We will see.

Edit...... I should add I have now had the timing everywhere on this little motor, I hadn't previously. It's very " timing sensitive. It runs best at 32 degrees, with it there it produced that best 60 foot. The pass before that I had run it at 36, and that slowed it down a whole tenth. Anywhere except 32 it's slower..... That said, I haven't tried 30, but I know going anywhere past 32 at all slows the car down.

Last edited by B3422W5; 09/11/15 02:43 AM.

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, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8

Re: You guys were right about the bigger carb [Re: B3422W5] #1910388
09/11/15 03:49 AM
09/11/15 03:49 AM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
C

Joined: Aug 2003
Posts: 43,007
Bend,OR USA
Years ago I tried a bunch of different size carbs. on a 440 bracket motor(452 C.I.) in a Duster that weighed right at 3200 lbs with me in it, I wanted to run Super Street with that car that year with a 727 and a trans brake. I started off with a Holley 650 CFM DP and ended up at the end of the year with Holley 1050 CFM Dominator to make it run the index at LACR, that car ran 11.70 ET with the 650 and got faster and quicker every time I put a bigger carb on it shock I treid a Holley 750 D.P., 850 D.p., 950 HP and finally the 1050 Dominator shruggy Most of them stupid Mopar V8 don't know the rules like the other motors follow whistling grin shruggy


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: You guys were right about the bigger carb [Re: B3422W5] #1910394
09/11/15 05:12 AM
09/11/15 05:12 AM
Joined: Aug 2014
Posts: 161
In a house near you
S
Street Monkies Offline
member
Street Monkies  Offline
member
S

Joined: Aug 2014
Posts: 161
In a house near you
well you have pressure differences, more fuel doesn't necessarily make more power.. It's the efficiency of the fuel.

Re: You guys were right about the bigger carb [Re: B3422W5] #1911024
09/12/15 11:33 AM
09/12/15 11:33 AM
Joined: Jan 2003
Posts: 16,917
NC
440Jim Offline
I Live Here
440Jim  Offline
I Live Here

Joined: Jan 2003
Posts: 16,917
NC
Originally Posted By B3422W5
Car acts funny with the 750, doesn't rap crisply, accelerates lazy.
Put the 950 on, in the water box car raps so quick it hits the shift light ultra fast, sounds different even, accelerates faster.
The 750 may need the idle circuit richened up. Perhaps the idle air bleeds, or even the idle feed restrictor on the metering blocks. That might help it rap crisply, but the 950 will still be quicker.

Page 2 of 2 1 2






Powered by UBB.threads™ PHP Forum Software 7.7.1