CARTER WCD Metering Rods

ABuick8

Member
Dear Straight Eighters,

I am undergoing the right of passage known as rebuilding a carburetor! So far it has been going swimmingly...except for the metering rods.

I was careful when removing the metering rods, because I was listening to a tutorial before the disassembly. I was told to be careful not to bend the rods; I saw why! Such intricate curves! Oh shoot. It did not take long for me to learn that the metering rods are supposed to be perfectly straight! (?)

The heart of this post, is WHAT TO DO. I figure there are three options: bend back the rods (unlikely), replace the rods with perfectly matching 75-685's (preferably), or --and hear me out -- replace the 75-685's with 75-686's. 75-685's do not seem to exist on the interwebs, and I feel blessed to have found 686's. The third option seems the most achievable. But, as I said, this is my first carb rebuild. I'm a quick study however, so I'm beginning to wonder if I can change the metering rods AND the jets in such a way that is satisfactory to standard 1952 Buick Super operational standards.

WCD's varied so much it's almost too much for me to find the exact matching part. Unfortunately I cannot find a site that will tell me what the numbers mean! Naturally, I want to keep the car its carburetor components as stock as possible. The question is, with little to no parts availability, what is my best choice? Am I doomed to scour America's swap meets for the rest of my life, praying only to find the mecca of metering rods, or is there another more practical option?

In summation, can I run 75-686 metering rods? Does anyone know where I can find 685's? Is it possible to satisfactorily bend metering rods into true?

Thank you all for your time (and patience lol).

-Your buddy, Pete
 
Pete, here is a cool site where the Carter WCD part numbers can be searched:


It's not much, but the data on 75-685 shows it was used only on 1950-53 Buick Ser. 40 and 1950-52 Ser. 50. The Carter carb models were WCD725S and -SA for 1950-early '51 and WCD882S and -SA for late 1951-53. Some alternate metering rods are shown if leaner operation is desired, the 75-702 and 75-703. The metering rod jet is a 120-158 with a .082" hole.

The only application shown for the 75-686 is on the Hudson Six from 1948-50 on Carbs WCD-647S and -SA. The metering rod jet here is a 120-121S with a .086" hole.

This is a guess, but the 75-686 metering rod steps are probably a bit larger in dia than those on the 75-685. Provided the Hudson rod doesn't bind in the jet, it would make the Buick carb run leaner. All the other dimensions would have to match such as overall length, hook diameter, step width, step position, etc. Don't know how to confirm this except by comparing the two rods side by side and using a micrometer on the steps.

One site indicated the metering rods can be changed without dismantling the carb. Different metering rods would affect engine performance in the 20-75 mph range. Changing the metering rod jets would be another area to explore. This can turn into a science fair project if one wants to do the experimentation required.

Another idea is to buy a used WCD725 or WCD882 carb for parts and hope the metering rods are OK.

It may help to consult a carb expert at one of the vendor sites such as:

www.thecarburetorshop.com

Their site indicates they can supply metering rods with the purchase of a kit or even used carbs.

Don't know how badly the existing rods are bent or in how many places. The trick would be to straighten them without introducing new dog-leg bends, plier chew marks, or pinched diameters. The tools to do it right would have to be fairly delicate. If the rod could be made to go up and down in the jet without binding, it might be a satisfactory repair.
 
Update: I have a friend who is a service advisor for a dealership I used to work for. There is an old-timer who was recently hired on as a master tech, so I enclosed the rods and jets in a bag for him to look at.

Thank you for Todd the link! Unfortunately my phone took a swim and they apparently only take calls and do not respond to emails. Hopefully the rods get a "pass." Although I am all for experimentation, in this case I don't want to leave anything up to chance. The Super hasn't run since I did the valve job (I've had the heads off twice; lapped them the first time, had the valves/seats cut at a shop the second time and it still won't start). I have (passable) compression, I have spark and I've set the initial timing a dozen times (and yes, 180's every other time just to be certain). Wayne (the old-school master mechanic) suggested that I rebuild the carb. Certainly needed to be done! With the amount of dust and debris in the carb it would make sense that something could have gotten lodged in some small orifice while moving the manifolds around.

Surprised the Carb King hasn't weighed in. It seems logical that some combination of metering rods and jets amongst all the different WCD models would yield close-to-factory fuel to air ratios. But like I said, I'm just trying to get the darn car to turn over. A complete rebuild is doubtlessly in the close future haha but hopefully I can put it off a while. And I say this every time, but I am extremely grateful and thankful for the support from this community.
 
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