Flow rating on a carter 2-bbl

-
/6 Matt

/6 Matt

30 Degrees Crooked
Joined
Jan 19, 2010
Messages
2,512
Reaction score
235
Location
Lincolnton, NC
Does anybody know how much the 318 Carter 2-bbl's flowed? i know there was multiple models used throught the 318' lifespan, so just a maximum and minimun is sufficent.

Thanks in advance.
 
Actually there weren't many different models used. It was the same basic 2 bbl carter used the entire 318 run with some pollution crap added later. Then the lean burn carbs had a circuit in them for that. If I remember right they were rated at 300 cfm but they aren't rated the same way (rated at a different pressure level) a 4 bbl is so what it converts over to is a mystery to me. Why they did that I don't know. Sorry, I know this isn't much help.
 
Actually that's exactly what I needed to know 8). Two barrel carbueretors are flowed at 3 HG of mercury and 4 barrels are rated a 1.5 HG of mercury because four barrels typically operate under lower vaccums. The important thing is, I now know that swapping my 1-barrel over to a 318 2-barrel on my slant six will give me 115 extra CFM.

By the way, to convert between pressure differences use this formula:(Flow @ 3.0" Hg) = 1.414 x (Flow @ 1.5" Hg)

Thanks for the info Fishy68:-D
 
Good deal. I learned something too. It sounds like that swap should be worthwhile. The small bores on the carter 2 bbl should have good velocity so it'll be responsive and more cfm should help top end.

BTW: Didn't they use a 2 bbl on the Super 6 setup? I think they did but it was a progressive type like a 4 bbl is if I'm remembering right.
 
Yes they did use a 2 barrel on the super six. I'm not sure if it was progressive, but it was definetly smaller than the 318 carb. Regardless, I scored a carb over on another forum for $20 to stick on my 2 barrel manifold and I got curious how I would gain as far as flow capability goes. The classic 2 barrel swap for a slant six usually guarantees at least 10 more h.p. and usually about a 2 mpg improvement.
 
flow rates for the six cylinder bbd ranged from 220cfm up to 280cfm. i think most federal cars used a 265cfm carb on the super six setup.
most of the 318 carbs were 280-285cfm from what i have seen
 
The Super six carbs and the 318 BBDs are different. IIRC the Super Six BBD had a smaller bore in order to get better throttle response. However I've had both in my hands at the same time before and they were not progressive secondary carbs.
 
I have been running a Super Six modification on my six for over 20 years now. I have used the Carter BBD off of the factory Super Six and off of a 318. I really like the way the carb from a 318 feels on it, as a daily driven car, to my understanding CFM rating is the 280-285. I use this setup with Hooker headers 3 into 1, long tube basically asphalt draggers. Mopar elect. Ign. With Orange box ECU and Accel Super Stock coil. Open element 14X3 K&N air filter. All on a basically stock 225. In proper tune and adjustments it sounds good and pulls well.with a true aluminized 2.25” dual exhaust w/ H-pipe and 2 glasspack mufflers. 904 Auto. Trans. w/ B&M shift improver. Back to an 8.75 742 suregrip and a 3.23 gear set. Wrapped up in a 70 Challenger, what a 3000lb car maybe. I’m happy with this it has run great all these years with just usual maintenance and 97 octane at the pump, 20 years. Thanks, Al
 
fishy68 said:
Good deal. I learned something too. It sounds like that swap should be worthwhile. The small bores on the carter 2 bbl should have good velocity so it'll be responsive and more cfm should help top end.

BTW: Didn't they use a 2 bbl on the Super 6 setup? I think they did but it was a progressive type like a 4 bbl is if I'm remembering right.
Click to expand...

It was a Carter BBD, just like on the 318, but it didn't flow quite as much. Basically the same outside appearance.
 
/6 Matt said:
Actually that's exactly what I needed to know 8). Two barrel carbueretors are flowed at 3 HG of mercury and 4 barrels are rated a 1.5 HG of mercury because four barrels typically operate under lower vaccums. The important thing is, I now know that swapping my 1-barrel over to a 318 2-barrel on my slant six will give me 115 extra CFM.

By the way, to convert between pressure differences use this formula:(Flow @ 3.0" Hg) = 1.414 x (Flow @ 1.5" Hg)

Thanks for the info Fishy68:-D
Click to expand...

Carter and Holley are not rated same. Seems to me I "knew" that Carter were rated 'wet'

Some "stuff" good or bad

THE CARBURETOR SHOP / Carburetor sizes and CFM
 
That's correct. Carter did flow their carburetors differently.
 
You must log in or register to reply here.
-

Back
Top