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.

 

[66fs]

I have extra screws, but really no need for seperate lockwashers though. They are yours for the asking.

 

[AR67GTX]

You do occasionally see some Carter tall jets come up for sale. I believe I found some on EBay for restoring the carb in my 67 GTX. And a member here helped me some tall jets for a 340 AVS I wanted to put as right as possible before selling it. Lots of rods and jets on EBay usually.

 

[Rebelrouser]

I agree I have used standard jets in an AVS with no issues. Today's fuel with alcohol in it requires a slightly richer jet and if it sits, can cause corrosion in older Carter carbs. Gas station up the street keeps 91 octane with no alcohol and that is what I use in all my older cars and even all my lawn mowers and weed eaters. I have used a small welding tip on my torch and carefully heated the jet and then removed them that way. If you drill and use an extractor, use the spiral wound ones so you can take it back out easily if you need to drill or heat some more. Knock on wood with a little heat and sometimes drilling I manage to get the jets out. What I would like to see is some kind of spray on coating to stop the corrosion in older carbs.

 

[AR67GTX]

Assuming this AVS did use 3 step rods, tall primary jets and domed rod covers, you probably need to spend some time identifying exactly what rods and jets are in it because they may be all wrong. The fact the jets are beat up indicates they have been changed out. And as mentioned, tall jets were only used for primaries so the primary and secondary jets should not look of identical profile. The picture above of the 2 jets you removed from the driver side look like they could both be short jets but it’s not possible to be sure from a top view only. It looks like the top jet might be slightly larger or the primary jet. If you can’t read the number on the jets or the rods the jets can be sized with a pin gauge or micro-drill bit set and the rods with a caliper gauge. People had strange ideas over the years in how to set up their carbs and many of them were not too valid.

So again it may all boil down to if you were satisfied with how the car ran except for initial accelerator opening, then just cleaning it up and changing out the pump and some new gaskets may be all you want to do. Or you may want to get it back closer to a stock calibration.

I may be wrong but on tall jet applications it seems like .089 tall primary jets were very commonly used. It seems the did most of the fine calibration with the rods. For this reason finding a set of .089 tall jets (new or used) may not be as hard as it sounds. If you decide to stick with the short jets I think it might be wise to use 2-step rods and flat rod covers if it doesn’t already have them. Just an opinion.

 

[HS 69 Charger]

Wow, thanks for all the replies and information. At this point, I am going to do a first pass with just cleaning and replacement of accelerator pump (including soaking in ATF as suggested). I will use the thin gasket on the intake as yes I have the mechanical well choke and the height would change that. I will follow up with the kind offer from 66fs on the replacement screws.
All of the extra info on the jets and rods was very informative including best suggestions on final removal and cleanup if I can get them out (as needed). I was able to read the numbers off all 4 jets and rods and it appears to be stock and matched as follows so that is encouraging as well.

Actual numbers were 120 392 on small jets. And 489 on large tall jets and 16 574 on both rods
Rods: 16-574 Read from both on my carb
From Mike's Carburetor Shop: 3 step metering rod: .065 x .064 x .055
Primary Jet: High profile. 120-489 Read from both jets
from chart this is size .089 and Noted as "High Step Jet for 3 Staged Metering"
Secondary Jet: Low profile. 120-392 Read from both jets
From chart this is size .092

The charts I used were from Mike's Carburetor Shop website documents for Carter AVS.

Again thanks for all the information as it is very helpful and informative.
All my parts are rotating through a sonicator with Berryman's ChemDip. Will then wash, dry with compressed air and inspect for any further attention before starting the reassembly. No Jelly or strange particulate was found in the fuel bowls. Just a more dusty residue. Exterior was pretty sticky around all the linkages so cleaning that should help as well as I'm not confident nothing was sticking (position wise).

Many Thanks,
Martin

 

[Rebelrouser]

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

I have bought carb screws from this company The Shop - Allstate Carburetor

 

[khryslerkid]

On the Eldebrock they have a replacement accelerator pump, neoprene not leather or rubber. Changed to one of the neoprene ones and haven't had any trouble for years. It's compatible with all fuels. This one is listed for the Carter and might be what you're looking for. Check the size and listing for your carb. Good luck.
Carter AFB, AVS Accelerator Pump High Performance | eBay