Inliners International Forums General Discussion Engines DUAL CARB HELP

I AM IN THE PROCCESS OF PUTING A DUAL INTAKE AND HEADERS ON REBUILT STOCK 235 IN A 58 CHEVY TRUCK, I AM BUYING UP A FEW OLD ROCHESTER B'S ON EBAY TO MAKE 2 MATCHING ONES , I WOULD LIKE TO KNOW DO ALL THE DESIGHNS FLOW THE SAME .THERE ARE A FEW DIFFERENT STYLES.THE ONLY THING THAT SEEMS DIFFRENT IS THE TOP. THERE ARE THE B'S & BC'S
AND ONE OTHER CANT REMBER. IF I CAN SET UP DUAL QUADS I AM PRETTY SURE I CAN DO THIS. JUST NEED A LITTLE HELP WITH WHAT THEY CAN DO. I HAVE SEEN THE TECH TIPS ON STOVEBOLT PAGE, I WANT TO USE ROCHESTERS, I AM STUBBERN, ON MY V8'S I ALWAYS RAN ROCHESTERS EVEN IF THE PACK WAS RUNNING DEMONS OR HOLLEYS. I AM OLD FASHION I QUESS. ONE MY DAD TAUGHT ME TO REBUILD A QUAD THAT WAS IT . IF IT WAS GOOD ENOUGH FOR GM IT IS GOOD ENOUGH FOR ME /////////THANKS FOR LETTING ME RAMBLE'//////

Rochester B, BC, BV is a great Carb!
THey will sit for weeks, months, YEARS, just dump a little gas in and it runs again, just like before!

There are (at least) 3 sizes of the B/BC/BV.
Here they are with my estimate of CFM using the "4-barrel" rating of 1.5 in Hg:
By Primary Venturi size:

1-1/16: 100cfm
1-11/32: 150cfm
1-9/16: 200cfm

I'd use two of the middle size.
The large size is almost like 1/4 of an 850 Holley double pumper - not the most responsive setup if they both opened at once. Middle size is responsive but 2 of them are still big enough to feed the 170hp or so you should make!

Stay with the smaller ones for a "stock" 235" engine.

More air/fuel won't make any diference, except in your fuel bills.

Good luck.

I have 3 bv on my 250 and it way over carbed i whis i know a way to lean them out but i lost when it come the that

////////////////////////////////////////////////////// do i measure from the top of carb or the bottom for those measurements. wich one is best b,bc ,bv style

To oldskool66:
If you dont like that 3x1v intake I will swap you a Clifford 4v with Holley 390cfm, I havent even run the Clifford yet, I just always wanted one of those 3x1v setups. If so let me know we will be up at the Monroe, WA swapmeet May 20.

To Galv77551:
The B/BC/BV are all pretty similar - to my knowledge:
B = Manual Choke
BC = Integral choke (Bimetal coil, gets heat in a tube from exhaust manifold, 62 only on the Nova)
BV = Divorced choke (Bimetal coil is down on the manifold, rod goes up to the carb, 63 and later Nova)

As far as the sizes above, that is the primary venturi size, at the narrow point where the booster assy is.
The small one 1-1/16 is so small it is barely bigger than the booster when you look down into it.

The medium 1-11/32 looks to me like a "normal" carb, the venturi necks down, then gets bigger again at the throttle plates.

The big one 1-9/16 is so big it barely narrows at all.

The 3 are obvious if you see em next to each other.

thanks for the info. i am going to buy a few more i quess when i have about 10 or 15 ill be ready to buid 2 extremely good carbs. and wont cost near as much as zeinths or stromberges. i got a parts lot from an old carb shop going out of buisness. it is a box full of plungers needles seats gaskets ect.//////////old school 4/ever////

There's a way to run that (3 carb) with a "progressive" linkage/cable set up.

Ask Larry (twisted 6/NOVAMAN) about the "how to" as he would know.

Good luck.