Carter AVS Rebuild Jet/pump/screw/gasket? Removal/Replacement

[HS 69 Charger]

I am rebuilding a Carter AVS 4638 carburetor on a stock 383 (Vin H) Automatic with A/C. Build sheet confirms 4638 as correct Carburetor. This carburetor is NOT original but was replaced around 1979 as new (replaced a Holly which obviously was also not original carburetor per build codes).
After disassembly I noted the follow with questions:
1. I found two of the jets stuck (on Choke linkage side) and the soft brass already rounded over. I expect the only sure fire removal is a drill and extraction tool (left hand thread) to force them out as there is not much to grip onto at this point. Before, I do that, I want to know how to identify the replacements and availability. I snapped a closeup of the two from the accelerator pump side. At this point I may simply clean the carburetor with these still in place. See picture.

2. The 8 screws holding the air horn to the main body have several with "failed" lock washers. 1 is missing completely and 2 are broken so that the washer no longer has the overlap (to lock). Are these stainless steel washers of standard size for the screw? See pic

3. The prime failure reason for the rebuild is the Accelerator pump. Any acceleration at any point failed. When I opened up the carburetor the piston leather had shrunk down so far the spring behind it was in full view. So that part is an easy fix. No questions here but you can enjoy a pic of a completely failed/shrunk piston.

4. There are two gaskets for Carb to Intake manifold. one thin and one very thick. I have heard mention to use the thick one to "lesson" the effect of the "hot fuel" problem. Which should I install.


Knowing the Accelerator pump was my original problem I might simple proceed with clean everything with a normal rebuild kit (new accelerator pump), while leaving two stuck jets in place.
or
do I persevere, I tear out the two stuck jets and find replacements.

Thanks for any suggestions.

Martin

 

[66fs]

Leave the jets, there are no replacements for the tall primary jets that I know of.

 

[AR67GTX]

I would probably agree on leaving them, but I would try to lightly de-burr the tapered entrances so they are smooth and uniform.

You do want to go back with a leather pump. They are more durable than the others.

You want to use a 4 hole gasket, assuming you have a factory 4-hole intake. If the thin and thick are otherwise the same then you can use the thick one if it doesn’t cause hood interference. I don’t know that just a thicker composition gasket will help much with heat transfer. To really cut down on heat you need a 1/4 or thicker spacer designed specifically for heat.

You might try Mike’s Carburetors for the screws although most I see do not have the captured washer and you have to use a standard lock washer. If you only need 3 or 4 replacements I would place a WTB as in the parts forum. I’m sure some folks have some spares from old cores.

 

[R413]

4638 os for a 1969. Use the thin base gasket on a 1969 or your choke will not work right.

 

[Geoff 2]

#4638 uses 0.089" pri jets [ closest to the front & tall]. Sec jets are 0.092" [ & are short ]. You can use Edel AFB or AVS jets for the secs. But as others have said, just leave the jets in place.

The acc pump plunger probably got that way because carb was not used for a long time, leather dried out & rolled up. With the new pump, lube the leather with auto trans fluid.

Screws & washers were not s/s. If you want new washers, just get some from a hardware store.

 

[RJRENTON]

I am rebuilding a Carter AVS 4638 carburetor on a stock 383 (Vin H) Automatic with A/C. Build sheet confirms 4638 as correct Carburetor. This carburetor is NOT original but was replaced around 1979 as new (replaced a Holly which obviously was also not original carburetor per build codes).
After disassembly I noted the follow with questions:
1. I found two of the jets stuck (on Choke linkage side) and the soft brass already rounded over. I expect the only sure fire removal is a drill and extraction tool (left hand thread) to force them out as there is not much to grip onto at this point. Before, I do that, I want to know how to identify the replacements and availability. I snapped a closeup of the two from the accelerator pump side. At this point I may simply clean the carburetor with these still in place. See picture.
View attachment 1842126
2. The 8 screws holding the air horn to the main body have several with "failed" lock washers. 1 is missing completely and 2 are broken so that the washer no longer has the overlap (to lock). Are these stainless steel washers of standard size for the screw? See pic
View attachment 1842127
3. The prime failure reason for the rebuild is the Accelerator pump. Any acceleration at any point failed. When I opened up the carburetor the piston leather had shrunk down so far the spring behind it was in full view. So that part is an easy fix. No questions here but you can enjoy a pic of a completely failed/shrunk piston.
View attachment 1842128
4. There are two gaskets for Carb to Intake manifold. one thin and one very thick. I have heard mention to use the thick one to "lesson" the effect of the "hot fuel" problem. Which should I install.


Knowing the Accelerator pump was my original problem I might simple proceed with clean everything with a normal rebuild kit (new accelerator pump), while leaving two stuck jets in place.
or
do I persevere, I tear out the two stuck jets and find replacements.

Thanks for any suggestions.

Martin

You can substitute the regular high jets using the standard height jet...just use the three step metering rods and metering rod cover plate and step,up piston. The mixture calibration may change slightly but its not the end of the world. Remember....don't just COMPARE diameter differences....calculate the jet/metering rod DIAMETER DIFFERENCE when the rod is in the jet and you'll be close....remember AREA NOT DIAMETER is what is important To remove the boogered up jet, consider using a wide blade (grind the blade od to fit the jet) and use an IMPACT SCREW DRIVER, support the carb body on a clamped surface and with a few sharp taps on the impact driver handle the jet will come out. I've done this many times.....sounds brutal but the impact driver helps. Yes jets can be interchanged......in spite of what others say.......just my opinion.......
BOB RENTON

 

[Geoff 2]

The information in post #6 is wrong & could lead to new problems. There is a very goooooood reason that Carter changed the jet length & used a raised-height piston cover with the three-step met rods. Using the short jets with the 3 step piston covers results in as possibility of the met rod coming out of the jet at WOT...& jamming. The 3 step rods & hardware changes were designed to improve part throttle drivability/fuel metering. Changing the relative heights of the met rod steps is going to undo that delicate balancing act with the resulting mixture being richer or leaner than designed.

There is absolutely no reason to take this risk.

 

[RJRENTON]

The information in post #6 is wrong & could lead to new problems. There is a very goooooood reason that Carter changed the jet length & used a raised-height piston cover with the three-step met rods. Using the short jets with the 3 step piston covers results in as possibility of the met rod coming out of the jet at WOT...& jamming. The 3 step rods & hardware changes were designed to improve part throttle drivability/fuel metering. Changing the relative heights of the met rod steps is going to undo that delicate balancing act with the resulting mixture being richer or leaner than designed.

There is absolutely no reason to take this risk.

What you state is a matter of opinion.....as I've done what I mentioned several times without any issues. The difference od minuscule.....0.015" in length of jet metering area....the parts can be interchanged.....using the corresponding parts..and to get better accuracy during the full range of function......the solution is simple......I'll do it my way to my carbs....and I really don't give a **** what you think or do to your carbs.......
BOB RENTON

 

[Geoff 2]

And I doubt many people care what you do Bob. The OPs carb is correct for his [ stock ] engine & only a DOPE would mess with the factory's carefully calibrated settings.

The model #4635, three models over, uses a different met rod for each side, such is the calibration accuracy.