Does there exist a 4150 Holley that flows a true 1000 CFM ? And with 1.75" butterflies ?
Maybe I should also specify the 4150 bolt pattern.

Or do you need to go with a Dominator with 2" throttles ?

To my knowledge, a downleg booster "850" has about the biggest combination of venturi and throttle bore,
and I think even those will not reach 900 CFM.

I kind of want to rule out a fuel injection throttle body, just a conventional carb.

Holley sells a 4150 that they call 1000 cfm. And maybe a few people claim a little higher. I wouldn't know how much they really flow.

If you use a 1.45" venturi HP main body along with a 1.75 base plate with slab sided shafts, it will flow over 1000 cfm.

Sure, you can get 1000+ CFM 4150 carbs. The least expensive is probably the QF 1050. I don't think the Holley 1000 is available anymore. BLP makes a bunch of big 4150 main bodies and I'm sure other carb tuners have big options. I've used a QF 1050 for years on the dyno. Really nice carb that makes good power.

Don’t know for sure, but I would suspect the 1.59 venturi 4150 would be real close.

Well here's why I'm asking about actual flow.

Quick Fuel has a Dom with 2" butterflies and 1.71" venturis that they are also calling a "1050".

Same flow as the 4150 "1050" ?

I don't think so.

I'll be keeping an eye on this thread cause i posted a similar question a few months back on this

Check out ATM Carburetors. Very reasonably priced.

Advertised carb CFM ratings are confusing, if not outright misleading

Can you get 1000+ CFM rated at 1.5" Hg from a conventional 4150?
- dry flow: yes
- wet flow: not that I've seen, although I suppose somebody may have

A "1050" 4150 annular 4150 w/ 1.59 venturi & 1.75" throttle bore isn't going to flow the same as a "1050" 4500 annular w/ 1.72 venturi & 2.00" throttle bore

Yes, its pretty easy to get well north of 1000 cfm from a 4150 baseplate. I use a twin Blade style from Mike Laws Performance via Tony Morris Carbs and Parr Performance . We are flowing a over 1250 cfm on a race 540 and, yes, we had to work pretty hard to get what we needed for this engine . We are carb restricted to 4150 baseplate and, we are still leaving power on the table but, at just shy of 900 hp , we did pretty well at wringing the neck off a 4150 baseplate carb. Yes, we are still pulling too much vacuum at wot so, we could truly make use of the 4500 base.
That said and concurring with others here, yes, you can easily get a good, solid, very tunable 1000+ cfm from a 4150 base.
BLP has a couple options along with those listed by others here.

Dom ( Thumper Carbs ) builds several 1000ish 4150 offerings as well as the twinblade if one needs the higher airflows on the 4150 baseplate/frame.
We are in year 4 with the twins, this one our second iteration with the newer blocks and mainbody.
Extremely tunable, deadly consistent and literally the best "leaving" carbs i have ever worked with- i highly recommend them for racing. I have not worked with them on the street much but, would not anticipate any issues.
One of the Tunability areas we really like is the "upper-jet" system with drop in boosters , much like a dominator. Instead of boosters being pressed in, they drop in and attach with a jet, so we can change flows at the booster and easily try different boosters/skirts etc.
Saves a ton of tuning time when on the dyno and when fine tuning at track.

See :
Thumper Carbs
Tony Morris Carbs
Parr Performance Carbs
Mike Laws Performance
or, little ole me if interested.
Blessings all.

I have a Race Demon with the removable sleeves. I made my 4150 carb into a 1050 using the parts they required, sleeves air bleeds etc... ran like rubbish. I was having atomisation problems, so I stepped it down to a 1025 cfm, huge improvement for my junk. It just needed a bit more venturie to get the signal happening. My experiance.

That can be a problem with the big bore 4150 carbs. The booster needs to match the venturi or else things can get messed up.

I had 2 Pro-Form 1050 bodies, one downleg and the other is a newer body with annular boosters. The annular carb was better everywhere from idle to WOT. The downleg was ok but part throttle was very hard to get tuned right. The annular was fast and smooth right out of the box.

Gus

Braswell 4825 will get you there.

Yeah, the QF 1050AN carb that we use on the dyno has annular boosters. It has always worked great on engine in the 600 to 800 hp range. Makes excellent power and the curves are always nice and smooth. A Dominator on a Dominator intake will make more power, but the 1050AN does a decent job for less money.

Are the proform 1050 annular main bodies a worthwhile upgrade to an existing conventional 850 DP in terms of cfm? I've got similar flow concerns- for my 540 the 850 DP isn't enough, but I also wanted to hold off on buying another complete carburetor. The jump to a dominator (or a dominator-sied EFI system) isn't in the budget for the next year or so.

I think you will love the way the annular performs down low. You don't usually "feel" like you get your money's worth when buying simple to install parts but you will be surprised with this upgrade.

Gus

Yes sir , it is possible. I have two APD billet 4150 style carbs 1040 CFM. One alcohol and one gas. I love them. Very consistent and the tune out of the box is great.

I totally agree. I took off a 9375 Dominator and replaced it with the old Holley 80514 1000cfm annular. Lost very little in performance, but the idle quality, throttle response and low speed manners overall were amazing for the combo I was running. 446" with -1 heads and way too big of a cam and it still behaved really well. I've kind of been on the hunt for a 80514, I think that's a great carb for 410-450" engines.

Flow improvements? Minor; probably < 20 CFM wet; I've come to think dry flow comparisons aren't valid when different booster types (down-leg vs annular) are involved

Atomization and booster response improvements? Yes

And... can you find one? I've been searching for a Proform 67218 main body and don't see one anywhere. I suspect they're being made in limited quantities these days.