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Another... Carb Stroker 489

El.Padrino

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I can‘t decide on what carburetor size or brand to buy. I have read a lot but did not get a satisfying answer.

Heres my car:

1968 Coronet
383 stroked to 489
Sidewinder ported aluminum heads 310cfm intake, 1.5 aluminum rockers, 10.4:1 CR
Performer RPM intake
MSD pro billet distributor, MSD 6AL
1-7/8" headers
2.5" exhaust
electric fuel pump
Hughes hydraulic flat tappet cam ([email protected]" 242/246 LSA110°)
Dana 60 3.54 gears Suregrip
15" wheels
727 trans with shift kit, deep oil pan
torque converter probably 10“ Hughes 2500rpm stall

expect around 550-600hp, street car, redlight racer.

I came to 850cfm size but may want to step up a bit due to ported heads. Or is a 950 to big?
Car will be driven from spring to fall, no cold or winter use. Is a choke (electric) still a good thing to have?

Don‘t want to waste hp on a wrong carb but still try to stay in a reasonable price range of around max. 700USD or less.

Thanks!
 
I run an 850CFM Quickfuel Q series mechanical secondary carb on my 500 in. RB stroker. Seems to be a good size as I dialed my jetting in and such without having to change a ton other than screwing with my idle circuit with my bigger cam. No choke horn on mine either....3 pumps and it fires right up.
 
Rear ratio & converter- IMO no bigger than 850, always liked vac.secondaries on the street.
 
Agreed, vacuum secondaries on the street. And depending on gear ratio and stall speed, I found that they like an electric choke for off the line acceleration. No choke and carb leans out w a backfire through the carb.
 
Rear ratio & converter- IMO no bigger than 850, always liked vac.secondaries on the street.

I am running the 4 speed and 3.91 gears in the rear, so I went with the mechanical secondaries. I agree with ya on the vacuum secondaries for most applications, especially if you aren't very fluid in carb tuning.

:thumbsup:
 
You are saying your tires are 15" wide, correct?? If not, then this cars gonna blow the tires off from light to light anyway...., which is fun, but not really a gain. If that's the case, you should pick a carb on the smaller side (even 750), with vacuum secondaries. That way, the ride will be more satisfying the other 99% time when you are'nt going from light to light. I know I'm risking the big red disagree button, but you need a taller gear and better converter in order to really utilize the proper carb match (like 1050), IMO.
 
You are saying your tires are 15" wide, correct??

Sorry, they are 255 wide on 15“ wheels on the rear atm. They will be upgraded to 295 later.

Electric choke? Yes, no?

Carbs I have found with e-choke:

QF Brawler Street Series 850cfm (around $445)
QF Super Street 850cfm or 880cfm (from $614-660)
Holley Ultra Double Pumper ($637)
Holley Street Avenger 870cfm ($470)
Edelbrock Thunder AVS 800cfm ($470)

Above are all with mech secondaries.
Below with vacuum secondaries:

Holley 4150 Classic 850cfm ($637)
Speed Demon 850cfm -VS ($590)

From the list above my fav is the Speed Demon 850cfm (Vac. Secondaries) or Quick Fuel SS 880cfm (Mech. Secondaries) right now. Found both for a reasonable price.
 
Last edited:
Electric choke works better daily driver. Also will close partially under hard off the line acceleration to richen it up so you don't lean backfire through carb. Manual choke will stay open and then you get the lean backfire.
 
I am running the 4 speed and 3.91 gears in the rear, so I went with the mechanical secondaries. I agree with ya on the vacuum secondaries for most applications, especially if you aren't very fluid in carb tuning.

:thumbsup:
Ah, but you have stiffer gears & 4-spd. Stand by my and others thoughts.
 
Ah, but you have stiffer gears & 4-spd. Stand by my and others thoughts.

Yea I am totally agreeing with you. I was just voicing my opinion on the 850 size for that motor. Vacuum secondaries for his application and most for sure if hes running an auto.
:thumbsup:
 
Well, what “I” would do is, a Quick Fuel 850 DP 4150 no choke contoured air entry. (Or a Holley HP) I don’t like vacuum secondaries. Your foot can control what is needed. If these carbs are to much money for where your at, then a Edelbrock 800 AVS will do just fine. An electric choke is nice and fine or the street, even more so when the weather is a bit chilly for a quick start, get up and go moment. But not necessary for operation.

(On the smaller Edelbrock carbs, I pick up more CFM by removing the choke plate up front and removing the choke control rods that run in the secondary side. Then plugging the holes they leave behind. I also narrow the boosters legs down. This is an EASY 30+ CFM.)

IMO, since your on the street, the wrong carb is the one that you can not tune. The Holley may be more adjustable and therefore more tune able but in the street, it’s not the end all and only worthy in heads up drag strip racing with big power.

However I noticed your choking your exhaust with small headers & a 2-1/2 inches with a low-ish stall converter. Also, how high is the valve being lifted? You state the heads maximum CFM rating but are you lifting the valves that high to take advantage of the heads flow? Why are you not using 1.6 rockers with the Hughes cam?

I can‘t decide on what carburetor size or brand to buy. I have read a lot but did not get a satisfying answer.

Heres my car:

1968 Coronet
383 stroked to 489
Sidewinder ported aluminum heads 310cfm intake, 1.5 aluminum rockers, 10.4:1 CR
Performer RPM intake
MSD pro billet distributor, MSD 6AL
1-7/8" headers
2.5" exhaust
electric fuel pump
Hughes hydraulic flat tappet cam ([email protected]" 242/246 LSA110°)
Dana 60 3.54 gears Suregrip
15" wheels
727 trans with shift kit, deep oil pan
torque converter probably 10“ Hughes 2500rpm stall

expect around 550-600hp, street car, redlight racer.

I came to 850cfm size but may want to step up a bit due to ported heads. Or is a 950 to big?
Car will be driven from spring to fall, no cold or winter use. Is a choke (electric) still a good thing to have?

Don‘t want to waste hp on a wrong carb but still try to stay in a reasonable price range of around max. 700USD or less.

Thanks!
 
Last edited:
There are a lot of different 950's . You cannot just say a 950 without qualifying what it is.

950 DP with 1.40" to 1.42" venturi with downleg boosters. They probably actually flow 840 to 870. Or, possibly one with a slightly larger venturi but with annular boosters.
 
A little smaller CFM, better velocity!
 
I can‘t decide on what carburetor size or brand to buy. I have read a lot but did not get a satisfying answer.

Heres my car:

1968 Coronet
383 stroked to 489
Sidewinder ported aluminum heads 310cfm intake, 1.5 aluminum rockers, 10.4:1 CR
Performer RPM intake
MSD pro billet distributor, MSD 6AL
1-7/8" headers
2.5" exhaust
electric fuel pump
Hughes hydraulic flat tappet cam ([email protected]" 242/246 LSA110°)
Dana 60 3.54 gears Suregrip
15" wheels
727 trans with shift kit, deep oil pan
torque converter probably 10“ Hughes 2500rpm stall

expect around 550-600hp, street car, redlight racer.

I came to 850cfm size but may want to step up a bit due to ported heads. Or is a 950 to big?
Car will be driven from spring to fall, no cold or winter use. Is a choke (electric) still a good thing to have?

Don‘t want to waste hp on a wrong carb but still try to stay in a reasonable price range of around max. 700USD or less.

Thanks!

Are you sure you want a carb? Might be a good time to put a Holley Sniper on there. The Sniper will work better than a carb plus it will provide you with data logging, digital display and can control the ignition timing.
 
I run a Proform 850 DP on my 496 in my 69 GTX.Car has 4 speed and 3.54 Dana. Engine is a stroked 440, mild port on Eddy heads, Comp hydraulic roller 242/248, Holley SD intake, 1 7/8 headers into a 3" exhaust. Just a few jet changes and carb ran great. Choke delete for this combo but where I live don't really need a choke anyway. Car is absolute blast to drive. Never any problems.
Frank
 
Well, what “I” would do is, a Quick Fuel 850 DP 4150 no choke contoured air entry. (Or a Holley HP) I don’t like vacuum secondaries. Your foot can control what is needed. If these carbs are to much money for where your at, then a Edelbrock 800 AVS will do just fine. An electric choke is nice and fine or the street, even more so when the weather is a bit chilly for a quick start, get up and go moment. But not necessary for operation.

(On the smaller Edelbrock carbs, I pick up more CFM by removing the choke plate up front and removing the choke control rods that run in the secondary side. Then plugging the holes they leave behind. I also narrow the boosters legs down. This is an EASY 30+ CFM.)

IMO, since your on the street, the wrong carb is the one that you can not tune. The Holley may be more adjustable and therefore more tune able but in the street, it’s not the end all and only worthy in heads up drag strip racing with big power.

However I noticed your choking your exhaust with small headers & a 2-1/2 inches with a low-ish stall converter. Also, how high is the valve being lifted? You state the heads maximum CFM rating but are you lifting the valves that high to take advantage of the heads flow? Why are you not using 1.6 rockers with the Hughes cam?

This setup was gone through often and discussed with several people and engine builders. There are always a lot of different opinions I appreciate but in the end it was narrowed down to this specs.
Piston to valve clearance will be an issue with 1.6, suggestion was 1.5 and lift fits the max. cfm rate of the heads well.
Stall was recommended 2,500rpms from several different torque converter manufacturers (with a 10“ tc).
Headers should be right, exhaust pipe diameter is just 2.5“ atm. Will swap later for maybe a 3“ stainless steel.

I am still with the Speed Demon 850 with vac secondaries and electric choke.
 
OK cool man.

So... the 850 Speed demon is the choice?


This setup was gone through often and discussed with several people and engine builders. There are always a lot of different opinions I appreciate but in the end it was narrowed down to this specs.
Piston to valve clearance will be an issue with 1.6, suggestion was 1.5 and lift fits the max. cfm rate of the heads well.
Stall was recommended 2,500rpms from several different torque converter manufacturers (with a 10“ tc).
Headers should be right, exhaust pipe diameter is just 2.5“ atm. Will swap later for maybe a 3“ stainless steel.

I am still with the Speed Demon 850 with vac secondaries and electric choke.
 
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