Fuel System: carburetor flow rate

[colt45sa]

Anybody know the flow rates on a 1955 WCFB vs a 1961 WCFB as found on Studebakers? Why does the later carb have the counterweight/damper on the secondary air valves?

[karterfred88]

Don't know about CFM rates but the early ones didn't work well on transition, the air valve, like on the AFB, slows down and smoothens the change in air flow to prevent bogging. This article says that since Carter didn't publish CFM rates all the rates are guesses anyway:http://www.jalopyjournal.com/forum/t...b-tech.851851/ Probably right, as even the early AFBs on the R cars are really guesses at 625.

[doofus]

Try around 385 CFM according to a carter book i found. the secondary air does exactly like Karterfred88 said, when secondary butterfly's are tripped the SAV slow's down air flow and creates a depression at fuel dump tubes to get fuel moving into air stream, without SAV you had to go easy when" jumping on it". Luck Doofus

[JoeHall]

385 CFM rings a bell for the WCFB on 56Js, but I believe they are a wee bit larger, in primary or secondary. I forget which.

[doofus]

I could go out in shop and look but i'll save that till tomorrow! Doofus

[Skybolt]

Try around 385 CFM according to a carter book i found. the secondary air does exactly like Karterfred88 said, when secondary butterfly's are tripped the SAV slow's down air flow and creates a depression at fuel dump tubes to get fuel moving into air stream, without SAV you had to go easy when" jumping on it". Luck Doofus

That is unless you find yourself with one of the few AFB's made without the counterweights, as I did. I had no idea there were such things as counterweights in AFB's until a few years ago. I had only had one before then, on my 64 Cruiser, and it didn't have any counterweights. I worked on it for years and had it so dialed in I had no problems no matter what I drove like. Then someone gave me an AFB about 10 years ago and I was puzzled at the counterweights. After reading many articles and books about them I found I had one of the rare AFB's made for racing. I'm trying to track it down as I sold it to a friend 25 years ago who then later gave the car he used it on to my brother. I just hope he still has it.

It is possible that someone had removed the counterweights but when looking down at the carb it looked different. No idea if an AFB made with counterweights will run without them.

Len

[bezhawk]

Chrysler used an AFB with side hung secondary venturies. I don't think they had the secondary air valve. Later on the had a similar designed AFB type crburetor called an AVS, that had the secondary air valv above the veturies like a secondary choke plat. It had an adjustable tension spring, so the cut in rate could be tailored to the individual engine flow rates. Edelbrock has this carb reproduced now, and is a better design than the original, because it has the secondry metering venturies, which the original AVS lacked.

[colt45sa]

Fellas, I asked about WCFB's. I have both designs; without counter-weighted air valves and with counter-weighted air valve. The 'without' is the 'correct original' as originally installed on my 67,000 mile '55 President State Coupe. The other 'with' has the correct Studebaker throttle arm and mount for the dash pot, but I don't know what year it came from. It is missing the brass ID tag. I was curious as to whether the later carb would have a higher cfm flow rate.

[doofus]

Look down on the venturi at the secondary side early non SAV carbs are marked 15/16. later carbs maybe larger, i have seen non stude wcfb's marked 1 1/16 with oval secondary blades. i have 2 early non SAV carbs for an R-1 project but no id tags. Luck Doofus