57 WCFB carbs

[Frank K.]

Is there a difference between a 245 HP and a 270 HP Carter WCFB carb for 1957, 283

[Frank D.]

Re: 57 WCFB carbs

Well the early 57 WCFB dual quads had idle air bypass screw in the base as a holdover from the 56 carbs. Later 57 carbs did not.

I know for 61 at least the most notable difference is the counterweights and the fact that the primary nozzles on the 270 hp carbs are cut at an angle (green circles) instead of straight up and down like the 245hp carbs..

I don't know if that is true for earlier cars.

[Frank K.]

Re: 57 WCFB carbs

Thanks for answering me. I'll have to do some more research but you pointed me in the right direction

[Frank D.]

Re: 57 WCFB carbs

These are '56 and early 270 hp '57 carbs that came on my '61 Corvette - which I sold to a 56 owner in Hawaii years ago..note the counter weights and idle air bypass screws (red arrows). Early carbs had 1151 & 1156 lid numbers... The point being, a lot depends on when your car was built..

[Joseph L.]

Re: 57 WCFB carbs

The JM shows the configuration of these carburetors. Just depends on the VIN. Remember that different main body numbers may have used different fixed vent sizes for the low speed and high speed systems. That is why it may be difficult to use a non-typical body with jets and rods that are typical for the engine/ HP.

There are two hidden items that affect driving. One is one the previous photo. The red circle shows the bushing that addressed the left turn issue with these carburetors. The other item is the vacumeter piston spring. This spring causes the metering rods to pop up during acceleration. You can see this my removing the vapor vent cover, and blip the throttle from idle. The rods move up.

The higher HP engine uses a weaker spring. Because the 097 cam produces less vacuum, that engine/ cam combination will hold the vacumeter piston (and metering rods) with less force. This causes the carburetor to run richer at lower throttle. A weaker spring keeps the metering rods closed longer and lessens the rich condition. (If the spring were removed, the rods would be in the lean condition at all times- not recommended.)

[Frank D.]

Re: 57 WCFB carbs

Well stated sir. The differences in the 097 cammed carbs was primarily about engine vacuum; hence the different vacuumeter spring and counterweights on the rear flappers. Many clone sets of 270hp carbs get the external nuances close but don't address the vacuumeter spring simply because the builders don't know about it.

The "anti-stall" bushing you see in my picture is something I add to all WCFBs that I rebuild and as I'm sure you know there is a Technical Service Bulletin addressing this modification.

[Frank K.]

Re: 57 WCFB carbs

Thank you both for the info. My build date was the 1st week of August 57. I know about the choke assembly with the heat tube entering at the rear. Now I am educated on what to look for if I find an original carb. I have the air horn and main body numbers but it's the little things you mentioned that I will look for. Much appreciated.