[66pmd428]

I've been trying to find the correct rebuild kit for a Carter AFB. My question... Is the new accelerator pump supposed to have some resistance at the bottom of the hole as opposed to falling right in? I've tried 2 different kits and the pumps provided are 11/32, I measure the old pump at 3/4 or possibly the less popular 23/32. The carb is a 4242s. Any help would be appreciated.......

[61-63]

Call Daytona Parts in New Smryna Beach Florida and they can build a kit with the correct pump and other parts for a 4242 kit. There is a spring that goes into the pump well before the pump.

http://daytonaparts.com/

[Cliff R]

What material is the pump seal, leather or flouroelostamer?.......

[steve25]

I see where your going with that question Cliff!
If it's leather then it's dry from not being in fuel and unswelled so no resistance will be felt during its travel.

[carbking]

Not sure if you purchased a kit from us or not, but no matter.

Carter used pump number 64-328s in the 4242s carburetor.

This pump is the same diameter of pumps used in earlier AFB carbs. This pump differs from earlier Pontiac pumps in that it does not have the internal check valve used in some of the earlier pumps, but still the same diameter.

One of the "tricks" employed by carburetor tuners on both Rochester and Carter carburetors is to simply bore the pump cylinder out to accomodate a larger pump. The larger cylinder thus has a larger volume which will deliver a larger volume of fuel by the accelerator pump.

So, it may possibly be that you have a carburetor that has previously been modified, in which case the pump in any kit listed for a 4242s will be too small. If the pumps you are getting in the kits are physically smaller than the one removed, this is probably the case.

However, if the pumps have a leather cup: the manufacturers of accelerator pumps place a cardboard cylinder tightly around the leather to protect the leather. Leather cup washers SHOULD be SLIGHTLY expanded before installation by running a blunt instrument between the leather and the thimble to GENTLY expand the leather. Once expanded, the garter spring will keep it expanded.

Jon.

[carbking]

Further:

Carter used the 3/4 inch pump in their "Competition Series" (read street racing or actual racing) AFB's.

Part numbers for the Comp Series carbs:

4758s - 500 CFM
4759s - 625 CFM
4760s - 750 CFM
4761s - 500 CFM (chokeless)
4762s - 750 CFM (chokeless)

All of these carbs used the largest pump ( Carter 64-418s).

If you find an American manufacturer of this pump, please let me know. I get tired of fabricating them by hand! They have been obsolete for decades!

Jon

[Mike Davis]

Jon, are the 4xxx series pumps different than the 9xxx series? like the 9755 Carbs? I thought all the Carter Comp series were the same.

[carbking]

Mike - Carter only made one group of Competition Series carbs:

The 5 numbers listed above on AFB's.

Plus

TQ 4846s (850 CFM) and 4847s (1000 CFM)

The original 9000 series was the high performance street series.

After F/M bought Carter, F/M labeled some of the "clones" as Comp Series, but they were not the same. After our first shipment from F/M of the clones, we have had nothing more to do with them, nor will we ever.

Jon.

[Kenth]

The 4242S uses a 11/16" diameter and 2.290" long pump, same as all 1966-67 Pontiac AFB´s except 1966 326 engines.
Doesn´t hurt to put a couple of engine oil drops on the leather shirt at install and expand shirt some as Jon said..

[geeteeohguy]

Originally Posted by carbking

Further:

Carter used the 3/4 inch pump in their "Competition Series" (read street racing or actual racing) AFB's.

Part numbers for the Comp Series carbs:

4758s - 500 CFM
4759s - 625 CFM
4760s - 750 CFM
4761s - 500 CFM (chokeless)
4762s - 750 CFM (chokeless)

All of these carbs used the largest pump ( Carter 64-418s).

If you find an American manufacturer of this pump, please let me know. I get tired of fabricating them by hand! They have been obsolete for decades!

Jon

Jon, I just got a nice leather accelerator pump from Carbs Unlimited for my WCFB Carter. ('61 Corvette) Other sources are Chicago Corvettes, and Mikes Carburetor Parts.

[66pmd428]

Thanks for all your responses.. The pump material is leather and as far as I know there have not been any mods done to the pump well. I will try to expand the leather and put a couple drops of oil on it. The kits I have are Walker part# 15299B and 15328B which I got locally.

[66pmd428]

Here is a pic of the pumps, though it may be hard to tell the size difference.

[carbking]

Originally Posted by geeteeohguy

Jon, I just got a nice leather accelerator pump from Carbs Unlimited for my WCFB Carter. ('61 Corvette) Other sources are Chicago Corvettes, and Mikes Carburetor Parts.

No problem on these pumps, they are commercially available (USA made) at the wholesale level.

Much different pump.

There are about 10 or so different diameter accelerator pump cup leathers. Several of these I either have to mold myself, or if there is significant demand, there is an American company that will mold a minimum of 2500 of one diameter.

They range in size from about 5/16 inch to one used by Cadillac on their V-16 that was 1 1/2 inches.

Jon.

[carbking]

Originally Posted by 66pmd428

Here is a pic of the pumps, though it may be hard to tell the size difference.

Looks like the same pump, with the new pump not expanded.

Also looks like the old pump should work fine, if you wanted to save the new pump for an emergency. Put a few drops of light machine oil on the leather to soften it.

Jon.

[Cliff R]

I get a few AFB's sent here from folks thinking they are Quadrajets. Not soliciting for any of that work, don't want it or any Tri-Power work either.

If/when this happens I use one of the pumps shown below, the larger is the 3/4" version, the smaller is the more common size typically found in AFB's used on Pontiac engines in the mid to late 1960's. I purchased some in both sizes over 10 years ago and not even sure where they came from, but they have been 100 percent successful in this new fuel.

Not trying to start a debate over pump cup preferences or anything of the sort, but I sought out these pumps after having a leather pump from a NAPA kit fail in less than 30 minutes!

It was exactly like the one in the pic above with the reddish/purple leather material. At a minimum with any carb I do here they are filled with fuel from an electric pump, and I work the accl to insure pump shot. The one that failed worked fine as soon as it swelled up a bit, good to go....WRONG. Went to lunch, came back, moved the throttle arm a few more times before dumping the gas out to dry it up for shipping...NOTHING. Not even a hint of pump shot. I removed the top and the seal was all buggered up prompting me to go in another direction........Cliff

[61-63]

I've never had leather fail in 30 minutes but the ethanol laced gas will ruin them if you do not drive the vehicle very often. The gas evaporates and the leather gets hard. You fill the float bowls and the leather softens up and the pump works. Then the gas evaporates and it gets hard again. Then soft again. ta da ta da. Very many cycles of this and the leather will not soften up anymore. IMHO the new ethanol friendly plastic pumps are the better way to go.

[shaker455]

Great Info Jon!