You guys were right about the bigger carb

It's faster with the 950 over the 750.
Got it to go 12.11 with the new 750( air was terrible)
Ended up at 11.91 with the 950. Best 60 foot to date with car on that pass.
Didn't have a chance to jet it down, know I left ET on the table, but with moving timing around and swapping carbs around it was enough for one night.

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.

Thats the thing with the SB.... they love the air...
then you just put enough fuel to it to burn right to
make the power... but they love air

LOL ......

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

What was the reason it wouldnt rev? I assume its fixed?

After the season think i am going to stick 4.56 gears in it, and remove these 4.10's. Trapping at barely 6k at the stripe
Problem is this hydraulic cam and springs are going to be maxed at 6500.
Might put a solid in it, have to talk to Dwayne about that...

Timing was off, guys at a shop next door used a fancy setup( digital deal) and set it wrong.
I went and bought my own light.
Plus this little motor doesn't have a lot of grunt from a roll in high gear.
Had too high of fuel pressure( 8), changed it to 6.5, new plugs, and the 750 shiny new carb is a dog

Interested in your combo would you share more info?

30 over 318 magnum
Lightened 340 crank, scat rods, diamond Pistons
Magnum RT heads, 2.02 valves, massaged.
Dual plane, air gap knock off
950 proform
231-238@50 hydraulic cam, 595 gross intake lift
10.44 compression
Cheapy 99 dollar 1 5/8 headers into dyno max bullets
8 inch convertor
904
4.10 gear, 28 inch tire, 3415 with me in it, flat hood.
71 New Yorker rear shocks, CE 3 way fronts, shift at 6200, trap at 6000

Thanks
I ask because my son is building his first car, it's a 71 Demon and he's starting off with a 318.

I see a solid lifter cam
in your future.

IMO, you have certainly have done the job quit well.

Nice run! I vote for the solid cam and more gear!

They usually are................good deal and it would be even faster totally dialed in........the carb that is.

Glad you got that figured out!

Still puzzles me about the 750 not working. Almost think there is internally something wrong with it. Shouldn't be that much difference( and I know the 950 is a wee bit fat)
Just surprised the bigger carb is so much better. I would have thought even a 650 would supply enough fuel.
Learn something every day..... Lol

AIR FLOW........the fuel is not the issue.........LOL!!!!

My stock stroke 360 was quicker and faster every time I went bigger and ended up w/an 850 speed demon(flowed 930)and went a best of 11.88 @ 114 mph at 3200+ lbs at L.A.C.R.`s high elevation track.........

I know, more air, more fuel, equals more power.
My point was at 6200 rpm max, how much air can 323 inches gulp in and burn.
My guess is some carb guru could probably put a 650 on this little motor and get it to run better than I have gotten it to run with a 950... Lol

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.

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

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.......

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.

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

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.

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

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

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............

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.

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 I treid a Holley 750 D.P., 850 D.p., 950 HP and finally the 1050 Dominator Most of them stupid Mopar V8 don't know the rules like the other motors follow

well you have pressure differences, more fuel doesn't necessarily make more power.. It's the efficiency of the fuel.

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.