"Best" carburetor choice(s) on which to focus tuning efforts?

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BradH
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"Best" carburetor choice(s) on which to focus tuning efforts?

Post by BradH »

Still working to get my street/strip junk back together, even though the engine was dynoed last fall.

Based on my 452 BB Mopar making about 680 HP and 600 torque, I'm expecting the car to be capable of solid low 10s at close to 130 MPH in street trim, which would be a few tenths quicker and 3-4 MPH faster than before.

I have a selection of 4150 carbs to work with and am curious if any of them stand out to other people as the most likely on which to focus my tuning efforts. Although I'd like to get one carb dialed in well enough to both drive on the street and run the best on the track, I'm not ruling out having one more street-friendly and another to swap at the track.

Here's "the herd", all of which are 4150s using 1.75" throttle bodies, fully tuneable billet metering blocks, etc.:

BG Gold Claw 1.425v downleg
- My only "known quantity" carb as it was on the car before when it was running mid-10s w/ the old engine combination; wasn't present for the dyno session, though
BG_GC_1_425.jpg

QFT/Proform 1.45v with BLP-modified Holley downleg boosters replacing the original boosters that came with the body
- Untested new build; interested in how it compares to the BG, since it's the closest in venturi size
QFT_1_45.jpg

QFT/Proform 1.50v with Braswell downleg boosters
- Untested in latest config after changing the boosters from the previous BLP-modified Holley downlegs used when dynoed

QFT/Proform 1.58v annular
- "Semi-tested"; hoping the part-throttle tune is refined from when dynoed
QFT_1_58_AN.jpg

Holley Ultra H/XP 1.58v (1.56v "850" venturi blended out) with Braswell downleg boosters
- Untested new build; also, my biggest downleg 4150

I have a Holley Ultra H/XP 1.60v "950" converted to BLP 12-hole x .600" ID annular boosters, but it's been something of a "problem child" testing a couple different configurations and -- to be blunt -- suspect it may need a complete main body swap in the future to be truly usable

Also, I've made a best-effort guess on their baseline tunes, but only the Gold Claw and the QFT/Proform 1.58 Annular have actually been run in their same basic config... and on the dyno the big annular was OK at WOT, but not so good at part-throttle. In many respects, it feels like I'm starting from scratch.

FWIW, member "PRH" (Dwayne Porter, who ported the heads and ran the dyno session) and I believe the two likely to be the best on-track performers are the QFT/Proform 1.50v with Braswell downlegs and the QFT/Proform 1.58v annular, since they both made good power & torque w/o having been really dialed in during the dyno session. However, I'm interested if others think there's a potential dark horse in the mix.

FWIW #2, we're talking about a 3800#s w/ driver, 4500-stall converter, 4.10 gears, DOT radials, full exhaust, drive-to-the-track street car.

Oh, I don't have pics of all the carbs, but did post a few for "eye candy"... :lol:
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by prairiehotrodder »

Are any two suitable to use together on a tunnel ram ? Looks like you have alot of dollars tied up in carbs. I'm not the smartest guy here but i would not build one for street and one for track. Get your favorite one dialed in for street and strip.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by BigBlockMopar »

Sell a few and you could buy one heck of an EFI setup and do your tuning from the driverseat on your way to the track... 8)
Nice stuff though.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by BradH »

Definitely staying with a single 4-bbl intake. If I can get one carb dialed in well enough to do both street driving & track duty, that would be ideal. If not, I can live with having a dedicated track carb.

AndyF has been suggesting that I sell all my carbs and go EFI, too. I've been following his Holley Sniper posts pretty closely, but am not ready to make that jump at this time.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by steve cowan »

Brad,
i wont sell any of my stuff any more,people want everything for nothing,you have spent so much time and money in those carbs and you know your stuff,i have seen you on mark and tuners site plenty,As for EFI well i recon you are not that guy,and as nice as the holley stuff might be i have a couple of mates who have self learning EFI (not holley) and they are still chasing there tail as they keep saying SELF LEARNING-SELF LEARNING and i keep saying tune it manually and then maybe self learning but what do i know,anyhow
i am all for the street carb and track carb deal as i have been in the same situation for last 12 months 500 hp sbc using a 830 annular holley on the street and i like to keep my spark plugs nice and clean and i am amazed how lean we can run these engines on the street,and i swap to a 950 hp holley at the track,i purchased billet metering blocks for the 830 (proform) and done transfer jet mod in the carb body and moved IFR down the bottom of the metering block so i am starting to get a bit of confidence,i have a 850 demon carb as well but have not used that on this engine.
that tried and proven BG carb is more than likely the bread and butter carb as far as the bigger venturi-throttle bore deals only dyno or track can answer that one,
CARBS FOR EVER sorry EFI guys,probably get sprayed for that :D
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by BradH »

steve cowan wrote: Wed Jul 11, 2018 4:23 pm ... you have spent so much time and money in those carbs...
True, but please don't tell my wife what all those shiny things on my work bench are actually worth.
... and you know your stuff...
More accurate to say I ask a lot of reasonable(?) questions. If I knew my stuff, I wouldn't have come away from my last dyno session w/ so many "?" swirling around my head about why the different carbs tested ran the way they did.
i am all for the street carb and track carb deal as i have been in the same situation for last 12 months...
Yeah, I've had carbs that ran well on the track that weren't so happy on the street, so I'm prepared for that to be the status quo. But I hear from a number of people that it shouldn't have to be that way and am certainly interested in trying to find a tune that works for both.
that tried and proven BG carb is more than likely the bread and butter carb...
Yep; it's my "go to" and the baseline against which the rest will be compared. It's always run well for me and had "reasonable" street manners, which I also believe I'll be able to improve.

There's some power to be found in something "bigger", even staying with a 4150, since Dwayne's got an old-school CFS (Competition Fuel Systems) Holley 850-based annular carb that cranked 8-10 HP & torque more than the BG on the previous dyno session when we ran them both on my old 600+ HP combination. Yet, he's the first to say it wouldn't be very happy putting around on the street.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by grant6395 »

I have had extremely good success with the sv1
Carbs. Both on the street and track. Great manners for both. Just a suggestion. Grant.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by jmarkaudio »

Depending on how they were blended the Holley 1.58 down leg should be the fastest, flow the most air. I did one, and it was about the same on the flow bench as the Quick Fuel 1.59. with the same boosters. If you have significant distribution issues in the intake the annular may work better, something you will have to test. The Proform 1.50 would be next in line. Why were the BLP boosters replaced with Braswell?
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by andyf »

One thing I've learned over the years is that dyno testing and street driving are two very different things, especially when it comes to carbs. Getting a carb to make good power at WOT on the dyno isn't super difficult. Cold start, good low speed manners, off idle transition, proper pump shot at all different throttle positions, etc., is a whole nother ball game.

For street driving I'd recommend the smallest carb you have. Then try it at the track to see how well it works. For drag racing only I'd use the biggest one you have and then try it on the street. You'll probably hate the big one on the street and I doubt it will be much, if any faster than the smallest one at the track.

But hey, what do I know. I don't even have a carb on any of my engines anymore......
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by BradH »

Mark: Re the Holley XP venturi blending: it was just me, my Makita & my calipers. As Elmer Fudd would say: "I was vewy caweful..." I practiced on an old 4781 main body first to get a feel for the work. The XP venturi came out very consistent in size, slightly smaller than the cast lip which can still be seen (barely) when looking up from the bottom of the throttle bores.
HLY 1.58v body with Braswells.jpg

Re the QFT/Proform 1.50v post-dyno booster swap... the BLP-modified Holley boosters had .450" venturi holes. We started with 82/92 jets and had to bump 'em up all the way to 88/98 to get the WOT air-fuel ratio rich enough across the 3500-7200 RPM pulls. Verdict: insufficient booster signal. I noticed that BLP recommends .450"-hole boosters for smaller than an "850" and .435" for an "850" and up. However, I decided to give Braswells a shot, because I like their design w/ the larger radius into the booster hole and the wider shear step below the hole than what's left after BLP machines a standard Holley booster to their specs.
QFT_Proform 1.50v body with Braswells.jpg

Also, I was originally going to put annulars in the Holley XP 1.58v, but decided to put Braswells in it instead, since I had the QFT/Proform 1.58v annular already to cover that venturi size & booster config. I think of it as a "proof of concept" on how big of a downleg config I can get to work... or not.

Andy: You're a couple steps ahead of me in the application of modern technology to an old-school ride. I'm still trying to remember what my car sounds like when it's actually running.
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Last edited by BradH on Thu Jul 12, 2018 12:17 pm, edited 1 time in total.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by BradH »

grant6395 wrote: Thu Jul 12, 2018 12:04 am I have had extremely good success with the sv1
Carbs. Both on the street and track. Great manners for both. Just a suggestion. Grant.
Interesting, but I gotta keep my options to what I own already.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by Tuner »

andyf wrote: Thu Jul 12, 2018 11:26 am One thing I've learned over the years is that dyno testing and street driving are two very different things, especially when it comes to carbs. Getting a carb to make good power at WOT on the dyno isn't super difficult. Cold start, good low speed manners, off idle transition, proper pump shot at all different throttle positions, etc., is a whole nother ball game.

For street driving I'd recommend the smallest carb you have. Then try it at the track to see how well it works. For drag racing only I'd use the biggest one you have and then try it on the street. You'll probably hate the big one on the street and I doubt it will be much, if any faster than the smallest one at the track.

But hey, what do I know. I don't even have a carb on any of my engines anymore......
Do you drive any of your test mules on the street or are they all dyno projects?
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by F-BIRD'88 »

Get or make a dual carb to single 4 bbl carb adapter and run 2 650 avs2 Edelbrock carbs. Get all the top end power of a big racing single carb. And all the street sweetness and drivability of a street carb, including choke,fast idle and progressive secondaries and easy of Tuning and no leak carb bodies. Edelbrock has the adjustable progressive linkage too.
The Blowershop has the 2 piece dual carb to single adapter.

DualQuads. I bet it will equal or exceed the single 4 bbl at the track, and far better on street driving ease and convince and dependability. Not to mention look BOSS.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by andyf »

Tuner wrote: Thu Jul 12, 2018 1:48 pm
andyf wrote: Thu Jul 12, 2018 11:26 am One thing I've learned over the years is that dyno testing and street driving are two very different things, especially when it comes to carbs. Getting a carb to make good power at WOT on the dyno isn't super difficult. Cold start, good low speed manners, off idle transition, proper pump shot at all different throttle positions, etc., is a whole nother ball game.

For street driving I'd recommend the smallest carb you have. Then try it at the track to see how well it works. For drag racing only I'd use the biggest one you have and then try it on the street. You'll probably hate the big one on the street and I doubt it will be much, if any faster than the smallest one at the track.

But hey, what do I know. I don't even have a carb on any of my engines anymore......
Do you drive any of your test mules on the street or are they all dyno projects?
I have a street/strip car but my car isn't as fast as Brad's. He might be willing to compromise more on low speed driving and highway fuel economy. I got tired of race carbs that don't really work all that great on the street and made the switch to EFI. Brad is smarter than me and works harder so he'll probably figure out the carb issue. I decided to give up on analog fuel metering and switch to digital.
Last edited by andyf on Thu Jul 12, 2018 4:12 pm, edited 1 time in total.
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Re: "Best" carburetor choice(s) on which to focus tuning efforts?

Post by BradH »

F-BIRD'88 wrote: Thu Jul 12, 2018 2:00 pm Get or make a dual carb to single 4 bbl carb adapter and run 2 650 avs2 Edelbrock carbs. Get all the top end power of a big racing single carb. And all the street sweetness and drivability of a street carb, including choke,fast idle and progressive secondaries and easy of Tuning and no leak carb bodies. Edelbrock has the adjustable progressive linkage too.
The Blowershop has the 2 piece dual carb to single adapter.

DualQuads. I bet it will equal or exceed the single 4 bbl at the track, and far better on street driving ease and convince and dependability. Not to mention look BOSS.
As I mentioned above, I gotta keep my options to what I own already.
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