Thread: carb choices

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Edelbrock 750 man. choke
or
Barry Grant Speed Demon 750 Dbl pump manual sec.
(I have both)

1973 Fresh .030 454

.030 over KB 202 Hyper Ure. true flattops w 1 valve relief (8.20 comp. w 118 cc heads)

#049 heads w stock valves (port matched only)

.010/.010 LS6 steel crank w full treatment

3/8 "thumb" rods

Full custom balance

ARP main studs and rod bolts

Weiand Excelerator Intake w 1" 4 hole spacer

Holley race (140 gph) Elec Fuel pump w 4#-9# regulator -

8AN supply line from tank to Fram canister fuel filter, 6 AN lines from filter to pump, 6AN forward.

NO power robbing accs. like no power steering or no mech.fuel pump, has roller rockers. manual Front disc brakes etc

Modern dual pattern , I502 - E524 Lift, w 1.72 factory ratio rockers, 214/224 Dur @ .050 on a 112 centerline etc.., 1800 to 5000 RPM range

Cloyes True roller Tchain set

Stock 049 Oval port heads

1.7 Stamped roller rockers

Felpro .038 Head gasket

The recommended springs

Chrome Moly 3/8 pushrods

3/8 guide plates

Recurved cast iron point factory dizzy w Crane XR1 elec conversion w rev limiter - I have it. I also have an HEI w a hot coil but stock otherwise.

Crane Fireball coil

8mm Taylor spiro core plug wires

Melling M77 stock volume oil pump w L88 spring

Hedman 1 3/4 Primary tube/3" Collector.

2.5" mandrell bent full length exaust w 3" Flowmasters

T400 w Transpac type kit (I am firmly committed to a 3 speed auto)

Stock Converter (for now)

USE- 3400# car w full tank and my fat a-- ,Mostly street cruising runs to shows + cruises (up to 100 mi's) ,no daily driving. Never see drag racing (except from the parking lot). pump gas and low grade at that.I fully admit alot of this is overkill but i had it and I FIRMLY believe in using up (or at least trying) what I have B4 spending more $$$.
I am fully aware that more can be done in the head/cam area's for bigger HP, but I think it is overkill for my use, The block as I said was done B4 for a drag car that never happened. Detuned + rebalanced for street use (sold the 7 1/16 bolt dimple rods, 13:1 forged pistons and square ports), but the bottom is SOLID for over my RPM range.

Anyone hazzard a guess to power numbers??? Which carb is better suited to this combo-Edelbrock 750 man. choke
or
Barry Grant Speed Demon 750 Dbl pump manual sec.
(I have both)

the difference between the 2 carbs is night and day. I am thinking the edelbrock is a very consevative choice for a 454, and will give you by far better drivability and miles per gallon. But alo a tad undersized to give you what the 454 has inside wanting to come out. But is very doable.

And the double pumper is going to need detuned quite a bit and is a too big for what you have, the mechanical secondaries are going to kill the type motor your running and the cars weight you are wanting to use it on. Its not your best choice, I would go with the edelbrock. Its going to be the easiest part to work with as far as tuning it. You will probably have to bump up the metering rods to get the most out of it. But you will get better mileage and a quicker turnaround time in tuning it to work for you.

What tranny and rear end gear are you running?

I agree with mooneye ^^^ For the revs you're running (<5000rpm) 750cfm will be plenty of carb. You'll definitely want vac secondaries for drivability and fuel economy. The Edelbrock is the way to go... I could _guess_ power you will get could be in the 300hp +/- ballpark maybe closer to 400+ tq. (and this is really a wild guess)

-Chris

p.s. smaller exhaust (2.5") might yield better tq/driveability... 3" IMO is a bit big... more for high rev power.

I would go with the Edelbrock 750. Double pumpers were always to much carb for street use. I run a 750 Edelbrock with an electric choke on my 454HO. It's a 454HO crate engine Gen VI four-bolt big-block, forged steel crank, forged connecting rods, and forged pistons, roller camshaft Camshaft duration (@.050 in) 211 degree intake / 230 degree exhaust with .510/.540" lift. Cast iron cylinder heads, rectangular port, 118 cc chambers deliver a pump-gas friendly 8.75:1 compression ratio. 2.5" American Thunder Flowmaster Exhaust with Hooker headers. Horsepower comes in at 425 with 500 lb.-ft. of big-block torque.

In a 72 Chevelle with a 700R4 and 3.73 posi rear it gets 15-17 mpg on the highway.

First off, I agree with the Edelbrock carb, and, my desktop Dyno says about 375 HP and 475 Ft Lbs.

Sounds like an OK combo.

I'll stay w the Edel. then. at least until I give a good try first. I was thinking of backing off the Demons rear pump adjustment to get rid of its function. The exaust is 2.5" ,sorry , the 3" is on my street legal drags 56. A Vac sec. 750-780 Holley be a better choice? If memory serves,the Edelbrocks actually flow less than rated.

I don't know about Edelbrock flow numbers not being accurate but I would personally prefer a vac holley mainly because I'm a holley guy and think the edelbrocks/carters are ugly ... on the other hand many have told me the edelbrocks are much easier to tune for the street than the holleys (and I can believe that after all the time I've put into tuning my dp for wide open not to mention street driveability). I wouldn't worry about not having enough carb... a 650cfm should be big enough for your combo at 5000rpm.

-Chris