Re: You guys were right about the bigger carb
[Re: justinp61]
#1909916
09/10/15 02:07 PM
09/10/15 02:07 PM
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B3422W5
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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
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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
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cudadoug
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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.
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Re: You guys were right about the bigger carb
[Re: cudadoug]
#1909988
09/10/15 03:39 PM
09/10/15 03:39 PM
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MR_P_BODY
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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
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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
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Thumperdart
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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.....
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Re: You guys were right about the bigger carb
[Re: B3422W5]
#1910027
09/10/15 04:55 PM
09/10/15 04:55 PM
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Monte_Smith
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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.
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Re: You guys were right about the bigger carb
[Re: B3422W5]
#1910098
09/10/15 07:32 PM
09/10/15 07:32 PM
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AndyF
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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.
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Re: You guys were right about the bigger carb
[Re: AndyF]
#1910100
09/10/15 07:44 PM
09/10/15 07:44 PM
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MR_P_BODY
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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
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Re: You guys were right about the bigger carb
[Re: AndyF]
#1910285
09/10/15 11:19 PM
09/10/15 11:19 PM
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Joined: Jul 2004
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Thumperdart
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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...... I thought it was a 950 though which will still work.
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.....
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Re: You guys were right about the bigger carb
[Re: AndyF]
#1910294
09/10/15 11:48 PM
09/10/15 11:48 PM
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Joined: Jun 2003
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MR_P_BODY
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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
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Re: You guys were right about the bigger carb
[Re: B3422W5]
#1910377
09/11/15 02:28 AM
09/11/15 02:28 AM
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B3422W5
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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
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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
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B3422W5
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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
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Re: You guys were right about the bigger carb
[Re: B3422W5]
#1911024
09/12/15 11:33 AM
09/12/15 11:33 AM
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440Jim
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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.
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