Thread: 434 stroker supercharged need carb help

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i have a brand new SBC 434 stroker with a holley 250 searies supercharger..and i dont know what size carb to run ..went to holleys web site and that was no help........ does any one have any info? need some help here......

Originally posted by STREET-DREAMS-2
i have a brand new SBC 434 stroker with a holley 250 searies supercharger..and i dont know what size carb to run ..went to holleys web site and that was no help........ does any one have any info? need some help here......

GOT THE NIFO

cubic inches times max rpm divided by 3456 will tell you what size carb you
will need.

so...

434 times lets say 6500 rpms divided by 3456 = 817cfm that you will need for
your motor.

more rpms bigger carb

Originally posted by STREET-DREAMS-2
GOT THE NIFO

cubic inches times max rpm divided by 3456 will tell you what size carb you
will need.

so...

434 times lets say 6500 rpms divided by 3456 = 817cfm that you will need for
your motor.

more rpms bigger carb

that might be true with a reg. motor, but im not sure with that blower.how much boost are you running? 10 lbs. of boost will make a big dif. in carbs. compaired to 6 lbs. and you can get by with less carb. on the st. with the blower than if you are gonna drag race it. what knd of boost do you have and what are you gonna do with it?

[QUOTE]Originally posted by lt1s10
that might be true with a reg. motor, but im not sure with that blower.how much boost are you running? 10 lbs. of boost will make a big dif. in carbs. compaired to 6 lbs. and you can get by with less carb. on the st. with the blower than if you are gonna drag race it. what knd of boost do you have and what are you gonna do with it? [/QUOT


LOOKING TO RUN 9 TO 12 LBS OF BOOST...STREET/STRIP.....

[QUOTE]Originally posted by STREET-DREAMS-2

Originally posted by lt1s10
that might be true with a reg. motor, but im not sure with that blower.how much boost are you running? 10 lbs. of boost will make a big dif. in carbs. compaired to 6 lbs. and you can get by with less carb. on the st. with the blower than if you are gonna drag race it. what knd of boost do you have and what are you gonna do with it? [/QUOT


LOOKING TO RUN 9 TO 12 LBS OF BOOST...STREET/STRIP.....

thats a lot of boost what size blower is that? will it put out 12 lbs of boost?

for the amount of fuel it will take to get you though the 1/4 ml. with 12 lbs of boost you will be changing carb to drive it on the st. unless you know what you are doing you will be better starting off some where around 6 lbs. of boost. been there done that.

Originally posted by lt1s10
thats a lot of boost what size blower is that? will it put out 12 lbs of boost?

HOLLEY 250 POWERCHARGER WITH A 400 CID AND A 91005 DRIVE PULLEY IT MAKES 10-11 PSI

Originally posted by STREET-DREAMS-2
HOLLEY 250 POWERCHARGER WITH A 400 CID AND A 91005 DRIVE PULLEY IT MAKES 10-11 PSI

THE MAX BOOST FOR THIS SUPERCHARGE IS 12-13 LBS. BOOST OR ATLEAST THATS WHAT THE INSTRUCTION/TECH MANUAL STATES...

Originally posted by techinspector1
The size of carb(s) or CFM required for a given application can be calculated by the following formula A: {(CID x RPM) ÷ 3456} x {Boost ÷ 14.7) + 1} = CFM required. The amount of CFM required will determine carburetor size and quantity. If you try to use a carb with less CFM than required, performance and economy may be greatly reduced.

434 x 6000 / 3456 x10 / 14.7 + 1= 1,265 cfm

YOU LOST ME ON THIS...... 1,265 CFM= 2 650CFM CARBS

Originally posted by STREET-DREAMS-2
THE MAX BOOST FOR THIS SUPERCHARGE IS 12-13 LBS. BOOST OR ATLEAST THATS WHAT THE INSTRUCTION/TECH MANUAL STATES...

if you have never run a blower you need to do some reading up on this thing, because it easy to break up a lot of stuff using the blower. you need to get that boost back down to something you can live with until you learn a little more about it you will be surprised at what 6 lbs. of boost can do. if i was you i get me a good book, on blowers, use the chart that tech just gave you, use about 6 lbs. of boost and start there. i ran one a few yrs and broke up a bunch of stuff before i did some series reading up on it and once i got to under stand them, then i had a lot of fun with it.

Originally posted by lt1s10
if you have never run a blower you need to do some reading up on this thing, because it easy to break up a lot of stuff using the blower. you need to get that boost back down to something you can live with until you learn a little more about it you will be surprised at what 6 lbs. of boost can do. if i was you i get me a good book, on blowers, use the chart that tech just gave you, use about 6 lbs. of boost and start there. i ran one a few yrs and broke up a bunch of stuff before i did some series reading up on it and once i got to under stand them, then i had a lot of fun with it.

WELL LETS SEE NOW....I'VE BUILT A 80 MALIBU WITH A 355 SBC WITH A 144 B&M BLOWER WITH 8LBS OF BOOST.... IN THE 1/4 THE CAR RAN 11.82@115 MPH......


NOW I HAVE A O-RINGED 434 STROKER WITH BRODIX 2.08/1.60 VALVES VENOILA N/20 TURBO/BLOWER PISTIONS SRP 3D RODS WITH L19 BOLTS 4" COLA CRANK MILODON MAIN CAPS AND ALL THE OTHER HAPPY HORSE @#$%


MY CARB PROBLEM IS THAT I WANT TO RUN 1 CARB, BUT I CANT FIND 1 BIG ENOUGH FOR THE MOTOR........SO IT LOOKS LIKE I MIGHT HAVE TO USE 2 CARBS......JUST TRYING TO FIGURE OUT THE SIZE TO USE..........

Originally posted by DennyW
Here you go Hot Rod. All you have to do is call them with your engine details, and they will wet flow test it for your setup.

they only carry an 850 cfm for a blower motor.........but thanks for the search/help.....

Originally posted by techinspector1
At 6 lbs, 6,000 r's, you'll need 1,054 cfm.

THEN WHAT WOULD I NEED @ 9 LBS OF BOOST?

Originally posted by STREET-DREAMS-2
THEN WHAT WOULD I NEED @ 9 LBS OF BOOST?

AND HOW DID YOU COME UP WITH THAT DATA/INFO?

Looks like the guys have given some good info on this subject. Suggest you contact a reputable engine builder for recommendations. Typically, a street driven blower motor will perform much better with smaller carbs.. two 650 double pumpers set up for a blower should be close to what you are looking for. Remember, 10 to 12 lbs of boost with 8:1 slugs will require race fuel only...been there done that & 3 to 4 mpg @ $4.00/gallon isn't much fun. The cam you are running will also be a huge factor in carb selection. Im currently rebuilding the 55 for street use only (pump gas) ..the 502 with an 8-71 straight up & moderate blower cam should be very happy with a pair of prepped 750's.