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Looking for a opinion on which is better, a downleg or annular booster. Looking at it, it appears that an annular booster would atomize the fuel better. I’m looking for a new carb, currently way under carbed with a 750BG, have a quote for a 1050 cfm 4150 from ProSystems, but thinking that something with annular boosters would work better. Best time to date is 6.95 at 102 at Clearwater (1.53 60 foot), feel it should be capable of mid 6’s Here are the specs on the car/engine:

’69 454 block Mark IV – 4 bolt main .030 over - 489 cu in. (4.280”)
Eagle 4.25 forged stroker crank
Eagle forged I-beam rods
JE forged domed pistons 10.25:1
Dart Pro1 Aluminum Heads – rectangular port 310 CC, 2.25 intake valves, 1.88 exhaust valves
Dart high rise oval port single plane intake manifold, port matched to heads – 4150 style carb base
1.00" Wooden Carb spacer
Barry Grant 4779-3
750 CFM with a 950 base
Crane hydraulic roller cam and lifters – Grind # HR-306-2S-14 .632 lift intake and exhaust
244 intake duration at .050 lift. 256 exhaust duration at .050 lift
Lobe separation 114 degrees
Springs, Crane Dual with damper 132 lbs on seat, 414 lbs open
Comp Ultra Pro Magnum chromemoly rockers 1.7 ratio, 7/16” stud dia.
MSD 6AL ignition #6420, MSD Pro Billet Distributor
MSD Rev Limiter #8671, 2 Step Retard Box #8739, 3800 pill
Hooker Competition, 2” headers, 3” exhaust, 3” Flowmaster mufflers, 2 ½” crossover
Painless Wiring Harness – 18 circuit Muscle car harness
31” x 18” 2 row aluminum radiator Dual Flex-A-Lite electric fans
Ladder Bars with single adjustable Strange Coilover’s
Ford 9” with Nodular iron center section, 4.11 gears with Detroit TrueTrac differential
Mark Williams 31 spline axles
Turbo 400 with full manual valve body, Trans brake, line lock, 3800 stall convertor
Wilwood 4 piston drag disk brakes on all wheels
10 point mild steel roll cage
Mickey Thompson P315 x R60 x 15 drag radials on Centerline 15 x 10 rear wheels
Fiberglass hood and trunk

Thanks for any opinions on this….bp
 

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i think annular would be the way to go. thats my opinion
 

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Downlegs will flow more. I'd only consider annular on a footbrake ride -- for throttle response. I fb with a HP750 downleg carb (525 horse 406). It was a tenth quicker than an HP750 annular and still had great throttle response.
 

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Annular boosters are generally better off idle due to the better atomization, however because of the larger design they restrict total airflow compared to downleg booster. Always a compromise....
 

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You might want to call Quick Fuel, get a quote for a custom larger 4150 from them. Annular booster is what I suggest for the larger venturi 4150's. Ask for Zack Baker.

One area you may gain more is with a higher stall converter, I'd shoot for about 4500 stall. Another is make sure your timing is locked to full advance.
 
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