AFB Parts
Is there a source or sources for individual AFB carburetor parts. In particular accelerator pumps, accelerator pump return springs, jets and metering rods. I looked on the Edelbrock web site for an accelerator pump return spring (goes under the pump assembly) but couldn't find anything regarding individual parts. I didn't want to buy a rebuild kit just to get a few parts.
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Re: AFB Parts
The current Edelbrock "Performer" carb has many of the same parts as the old AFB. Some of those parts are sold by Jegs and Summit Racing. Look at those catalogs. -
Re: AFB Parts
Greg-----
The Carter AFB carbs are manufactured by the Carter Division of Federal-Mogul Corporation. Presumably, they have available parts for the carbs. Whether they currently have available parts for "historic" model AFB carbs is another question and I don't have an answer for that. I would expect, though, that parts that are common or interchangeable from current models to "historic" models are available.In Appreciation of John HinckleyComment
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Re: AFB Parts
Some will shutter when I say this, but the Chicago Corvette catalog has one of the largest selections of Carter carb parts...Comment
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Re: AFB Parts
Greg;
If you don't mind my asking; what are you intending to do with the parts, i.e. Are you looking to replace missing parts? Are you planning to "tune" or modify an existing carb?
A lot of tuning stuff is available at the sources previously mentioned, particularly Edelbrock with their replacement performer series. If you need to replace missing parts, such as pump springs or perhaps choke components, you can get some from the usual vendors including Dr. Rebuild or just look around for some donor carbs. Kits do not come with either pump springs which makes that a problem as you must save them from your existing carb, and actually transfer the pump spring. The pumps can also be made differently by different mfg's and may not be transferable without some modifications.
I have two carbs that I have used to build up one good unit to deal with the gas available today. It took a while to get all the parts I needed and to tune it right, but it can be done. I also had a lot of old parts and some aftermarket items to use like an electric choke.
Stu FoxComment
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Re: AFB Parts
Stu,
I have a 3269 AFB that will not always come back to the set idle speed. If the idle is set at 800 RPM it will return to 1000-1200 RPM when driving the car. I can sometimes get it to return to 800 RPM by blipping the throttle or by raising the hood and manually moving the throttle linkage. The carb is restored, the throttle shaft is rebushed and free, the linkage, accelerator spring and setup are correct for a 340. If I move the linkage to the accelerator pump from the throttle it will return to 800 RPM. It seems that the spring under the accelerator pump is thin and wimpy and does not push the pump up hard enough. I have compared the spring to the one in my replacement 3271 AFB. The spring in the 3271 is much stiffer. The high idle causes some dieseling when I shut the engine off. Not a big problem but its not right.
When at cruise under light load there is a slight surge that only the driver can feel. The 3271 AFB I had on the car up untill this year did not have either problem. The surge indicates (I think) a lean condition which can be tuned out with metering rods. I don't remember what rods the carb has but when I measured them the second step was not what the book says the diameter should be.
So my short answer is I want to correct the idle issue and do some fine tuning of the carb.Comment
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Re: AFB Parts
Is your distributor working properly and the advance mechanism returning to its base position? Sometimes a little cleaning and light lubrication in this area will solve a similar problem.Comment
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Re: AFB Parts
Your 3269 AFB metering rods are the same as the ones sold at Summit and Jegs for the current Edelbrock Performer. I believe the jets are the same too. If the part numbers aren't the exact same, one is an obvious derivative of the other. The part numbers indicate the two sizes of the rod.
What I've done is to buy some junk AFBs on the EBay that I scrounge for parts. If the accelerator pump spring from the 3721 works so good, why don't you use it on the 3269?Comment
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Re: AFB Parts
Greg;
First off, my understanding is that the spring under the pump is not there to push the pump back up, nor does it even assist much in that function. It's primary purpose is to force the pump seal outward in the pump chamber to get a good seal against the wall of the chamber during the pump stroke. If your throttle is not returning to the idle stop screw, which is often the case with AFB's, and assuming the throttle shaft and butterflys are free and there is no binding or interference with say the secondary, pump or choke linkages, then you may have to do what others of us have done and that is add a booster throttle return spring or a stiffer return spring. The latter can actually be more difficult if perhaps you choose to modify a stock spring by cutting it down. If you don't leave a long enough straight end to the throttle, it will hang up on the throttle linkage.
What I do is add a very light booster spring for every day use which I can put on and off easy for show. It does not add to the throttle feel (not stiff), but is situated with just the right mechanical advantage to help close the throttle down to idle. Now I have had to use this on each of the two carbs I have had on the car for the last 17 years (a 3720SA and my best a 3721SB - my original 3461S was stolen in 92, and I used the same spring with that one too). On my 3721SB, my main throttle spring clips into the throttle rod 90* end through the throttle arm. The light spring clips into a small hole in the arm just below the throttle rod. On my 3720SA, I have to use a home made bracket on the upper rear valve cover screw and connect to the lower part of the throttle arm where the TVS transmission linkage would connect. There's always a way.
I believe your 62 uses the white throttle return spring, which was the same one incorrectly specified for my 63. I struggled with them for many years before going to a 64 - 66 black spring, but even it was not adequate.
Your surge is no doubt a lean condition which is made even worse by today's gas. I had some hesitation and surge and I cured it with jetting changes as well as using some primary clusters with different air bleeds. I also use an electric choke which not only controls the choke better (close and open), but eliminates the slight (1.5 to 2" Hg) hot air bleed through the choke. I have also found that Tomco fuel inlet valves seem to work better than needle/seats for controlling the float levels.
Where do you stand with heat at the carb? Do you have your heat riser wired open for the summer? What kind of base gasketing are you using?
Stu foxComment
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Re: AFB Parts
I'll answer a couple of questions here.
My centrifical advance is OK. I have checked it. No problem with idle before the carb change from 3721 to 3269.
Chris, I considered changing the spring but I didn't want to mess up a working carb to fix my other problem. Might end up doing it anyway.
Stu,
I don't know what the relationship is with the linkage between the accelerator pump (lower spring) and the throttle stop but it seems to add a little push to seat the throttle against the stop screw. I know it sounds crazy but there is a definate difference in the effect of the two springs that are under the accelerator pumps in my two carbs.
The carb gasket is a typical composite or paper gasket. I took the heat riser out a long time ago and just use a fuelie spacer in the exhaust. I don't know if the passage in the manifold is blocked but I suspect not.
I have used a helper spring on the throttle but it is not correct and I have the NCRS, must be correct mindset. The car got a Top Flight at the National Convention in 2008 at St Louis so I want to make it correct. Even though I am always tempted to "improve" things to make it drive and work better I figure if it worked when new I should be able to get it to work correctly now.
I have read your other posts on AFB carburetor tuning with great interest and appreciate you sharing your experiences. I downloaded a file off the Edelbrock website on tuning the Performer carbs which is very helpful in explaining how to make incremental tuning changes. I am trying to learn how these AFBs work. Even with the right "numbers" on the carb it is difficult to tell what has been changed internally from new.
I will check the sources for parts you all indicated.Comment
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Re: AFB Parts
Greg;
Sounds like you're on top of your situation or at least are headed in the right direction. If you have any specific questions or items I may be of some help on for you, please either post, or send me a private message or E-Mail, and I'd be glad to relate to you whatever I might know or learned in my experiments. I can tell you this much, and I am repeating myself, I am so pleased with the way my car is running now that it is almost scary. It has never run so well under all ambient conditions. Living here in Florida that's saying a lot.
Stu FoxComment
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