Opinions on best carb for big wedge street/strip motor

[440rb]

Hi, were running my mates RR next year with a totally new combo, I don't know all the full spec but can tell you what I know, car will be raced and run in brkts and on a lot of short trips on the street, would appreciate your thoughts.

3850lbs?...10:1cr 589ci, 4.500x4.625? Mega Block, -13's, 365's/385's?, small solid roller .620" 112ls don't know duration, could be the Indy R-1 cam?....440-2 intake, 2.25" hdrs, 727, 4.10 dana, caltracs/mono's, 10x29's bias.

Motor has been dyno'd twice,
with 850DP =714hp/742ftlbs rpm's?
with his 950DP =691hp@5700/724ftlbs@4000, 1.9vac on WOT...the dreaded 950 carb!.

They tried a 1050 Dom as well and it only made another 3hp more, lots of variables on dyno time/tuning, prob not much, but it deff needs a bigger carb. I was looking at either a QF1050 4150 (1.75" bores)or a 1050-1150 Dom+adapter if we have room with current 6-pk scoop, going to run it as is to start to get a base but I know it can run better without that 950. Other considerations later will be a better cam to use the heads more, comp won't change.
thanks.

 

[vance.dykes]

go e.f.i. port style straight shot to cylinder.like the pick that has been showing on the home page.

 

[Tex013]

Hi, were running my mates RR next year with a totally new combo, I don't know all the full spec but can tell you what I know, car will be raced and run in brkts and on a lot of short trips on the street, would appreciate your thoughts.

3850lbs?...10:1cr 589ci, 4.500x4.625? Mega Block, -13's, 365's/385's?, small solid roller .620" 112ls don't know duration, could be the Indy R-1 cam?....440-2 intake, 2.25" hdrs, 727, 4.10 dana, caltracs/mono's, 10x29's bias.

Motor has been dyno'd twice,
with 850DP =714hp/742ftlbs rpm's?
with his 950DP =691hp@5700/724ftlbs@4000, 1.9vac on WOT...the dreaded 950 carb!.

They tried a 1050 Dom as well and it only made another 3hp more, lots of variables on dyno time/tuning, prob not much, but it deff needs a bigger carb. I was looking at either a QF1050 4150 (1.75" bores)or a 1050-1150 Dom+adapter if we have room with current 6-pk scoop, going to run it as is to start to get a base but I know it can run better without that 950. Other considerations later will be a better cam to use the heads more, comp won't change.
thanks.

I ran an adapter on my 505 it fit under a six pack - just and that was with a M1 intake which is 1"lower than a Victor . I found afr was all over the place . I bought a Super Victor afr was better and it was a neater better fit . You might be better off with a custom carb for that big a motor if you want to stay 4150 type carb. You can get billet big bore or 2 blade units . For the cubes I would go 4500 and probably look to a 1150 or even a 1250 . That's a lot of cubes to feed

Tex

 

[440rb]

Thought about going up to 1250 as well Tex, big cubes for sure but not much else in the motor cam wise. Its a pain at the moment not knowing exactly whats inside it and how good the heads are. Maybe a custom Thumpr carb. Didn't think of efi, thats another ball game.

 

[PRHeads]

My .02......

There are a variety of “950” carbs.
Exactly what do you have?(venturi diameter and throttle bore)

If the carb you used on the dyno was working properly, it’s unlikely there’s much power on the table with another traditional (as in 4 separate barrels) 4150 carb.
Maybe 15hp.
Again..... this is assuming the current carb works well, and that all you’re doing by changing to a bigger carb is gaining capacity........ and not capacity plus improved function.

The motor isn’t making very much power, which means it’s not burning a lot of fuel, which means it’s not using that much air.

Ron Wilson’s 572 made 715hp@5700 with a 440-2 manifold.
At 6100, it was only using about 950cfm.

Same motor with a 337 manifold and a 1” spacer, going from a Mighty Demon 850 to a QFT Q1050 was only worth a couple hp.

 

[440rb]

Good info, much the same as Dominic said, the word "function" being relevant, and what we saw on the dyno here is similar. I'll have to look into exactly what carb he has and go from there, its an older 950 (830?) carb, no bleeds etc. Looks like tops would be a billet 950>1050, he will be trapping in the 6300rpm range with slip. Combo is sure a strange one but it suits him well currently and should do what he wanted which was to run 10.5 or better, its all there and ready to drop in, it has potential to become something better later.....thanks

 

[LemonWedge]

A little off topic, but since were talking carbs....
Similar to the XP 850 bore & plate configuration is the HP 1000. A little while back I swapped out my older downleg 830 DP for a brand new HP annular 1000. The swap was good for about a tenth on my combo, but mostly I figured it was a carburetor I could grow into with future changes to my mild 451. What was surprising to me was that with the bigger throttle bores of this 1000 vs the 830, I figured I give up a little throttle response. Not so! In addition to the gains up top, It was also noticeably more crisp down low and off idle. I attribute this to the annular boosters. I’m now a believer in going to a larger carb with annular boosters. It’s interesting to me though that Holley offers annular boosters in the HP line, and they are standard fare in the dominator lineup, but they don’t offer an XP carb with them...... hmmm???

 

[biomedtechguy]

The answer to this question, for me, is THREE carburetors, all at once, with some help from Promax! Around 975 CFM if the 1,350 in 2bbl CFM measurement standards is converted to the equivalent in 4bbl CFM.

 

[440rb]

Well I'll throw this into the mix re big carbs/CI/rpm and function>
back in 1985 I ran a street/strip 10:1 340 '71 Cuda, 727, motor was all stock+ had a .484/284 purple hyd. in it/3500stall/3.55's/hdrs/4779 750DP, ran well, trapped@around 5700. I put a 4781 850DP on it +2"spacer and it picked up nearly 2/10ths in the 1/4, rpm stayed the same, was sold on big carbs since then. I installed a 50cc fr pump on it, milled the choke off, drilled the butterflies, pump cam/shooters and bigger jets etc. and it ran even stronger, noticeably so on the street as well. So this wasn't a race engine with ported heads/big rpm/5000stall/gears etc. combo, why did that work?....perhaps relation of bore size/stroke/head size was the answer but rpm wasn't there to justify a carb of that size. All the other racers in the class kept telling me the carb was too big, so@the time a guy running a Ford Cortina with a rover 3500 v8 (buick 215), it was a stick car and well trick. I persuaded him to try my 850 carb, he was up for it..........well result 2/10ths quicker but throttle response was naff of course and he went back to his 600. But that shut them up for good!!

This 4.625 stroke motor is a different ball game and lazy compared, you have to keep air speed up for good functionality but@5800rpm only a small hp increase going to a 1050 Dom is strange even with the small cam that it has. Plenty of testing ahead of us.

 

[440rb]

ok so now explain why and your theory, I'm all ears.............

 

[biomedtechguy]

I ran an adapter on my 505 it fit under a six pack - just and that was with a M1 intake

If I read that right, you had 3x2bbl carburetors on an adapter on a M1 intake?
That must have been quite an adapter!

 

[33 IMP]

@biomedtechguy , i think he is saying he ran a dominator on a 4150 style manifold with an adaptor, and it barely fit under a sixpack scoop.

 

[biomedtechguy]

@biomedtechguy , i think he is saying he ran a dominator on a 4150 style manifold with an adaptor, and it barely fit under a sixpack scoop.

OH!!....
Well, nevermind then...

 

[33 IMP]

True 850 dp on a 440, 1.93 cfm/cu in.
1150 dominator on a 589, 1.95 cfm/cu in.
Im surprised the 1050 only helped 3hp, i'm not surprised the "950" didn't make power. Almost everybody that has tried a bigger carb on a big mopar has gone faster.
If that was my 589, i would try a 1250 on a super victor.
Edit: as an aside, i don't for a minute believe that a "1050" 4150 style carb flows the same as a 1050 dominator!

 

[biomedtechguy]

If that was my 589

I'd definitely have to buy different tires!

Wow, what a mill!

 

[440rb]

True 850 dp on a 440, 1.93 cfm/cu in.
1150 dominator on a 589, 1.95 cfm/cu in.
Im surprised the 1050 only helped 3hp, i'm not surprised the "950" didn't make power. Almost everybody that has tried a bigger carb on a big mopar has gone faster.
If that was my 589, i would try a 1250 on a super victor.
Edit: as an aside, i don't for a minute believe that a "1050" 4150 style carb flows the same as a 1050 dominator!

I agree, they don't and I also agree that 98% of people have gone faster with a bigger carb on a mopar not just me, how much faster, well here's another example>

My mate who ran a 446ci in a 3150lb Dart
12.5:1cr, Eddy MCH heads@around [email protected]
Dc. .590/[email protected] SFT cam
Victor intake 950 carb
5000stall, 4.56/13x31
low 10's@131@6700rpm trap
Put a 1050 Dom+adapter on, picked up only a few 100ths>1/10th+1mph max.

Trying to pick the best carb for this 589 combo is not going to be easy, ci dictates an 11>1250, but the dyno says otherwise, we'll get there. Max ET is not so much important as consistency unless were in the 10 teens. Everything I've read so far says a 950 flows around 820>830 and an 850 has larger venturi and flows more which showed up with the dyno pulls on this motor, +10>15hp but not that much with a Dom.

 

[33 IMP]

Yep, your results may vary. Then again, if i remember correctly, Mike Gaines on here changed from a 4150 to a dominator, on the gtx ( at least i remember it being a gtx, i'm not sure) that he recently sold, and picked up somewhere around 3-4 tenths.
Sometimes there's no way to know what works till you try.

 

[440rb]

 

[PRHeads]

On Ron’s 572....... 440-2 with a
Mighty Demon 850 with open spacer vs an 1150/4500 on a 2” adapter...... about 8hp better with the big carb.

Obviously, if the motor were making 150-200 more HP....... you’d see a bigger difference between the carbs.

The motor just isn’t all that dependent on carb area in its current configuration..... which is 1.21hp/ci...... or the same efficiency as a 540hp 446.

Is there any a/f ratio info on the dyno sheet for the two carbs from when that 589” motor was on dyno?

The 1050 made 3hp more than which other carb?

I’ll add one more thing.......
Until I had the motor in the car and at the track....... If buying a new carb is a budget concern item....... I’d wait till I had some passes on it to make sure the converter was pretty damn good before I spent the $$$ on a carb that, as dyno testing has shown, might only be worth a handful of HP.

Whereas if the converter sucks....... the car won’t ever put up a good number....... no matter how good the carb is.

 

[PRHeads]

Sometimes there's no way to know what works till you try.

I tell people that all the time.

Every combo is different.