Carter AVS 4968S

[RWCearley]

Hello group. Just recently joined with my 1971 chrysler New Yorker 2dr HT 440 TNT currently undergoing a complete restoration.

Many yrs ago I purchased the correct AVS carburetor. When the Chrysler was new, my dad was not satisfied with its performance and blamed it on the carburetor and replaced it (many times over its life.) I now have the correct carburetor and intend to use it. I have the specifications in the shop manual for this carburetor.

My question to the group: are the original specifications (jets and rods) too lean? Is there a better combination for today's modern fuels. I plan to use 90 octane non ethanol.

 

[Davea Lux]

It should work with the non-ethanol fuel. Main problem comes with the ethanol blended fuels which have different flow characteristics. I would install the carb as is and see how it runs. You can always do whatever tweaking to the mixture settings later. The 90 octane fuel is not quite as hot as the super octane fuels that were in use when this vehicle was new. You may (likely) have to tinker with the timing and advance settings to get the engine to run properly without pinging.

Dave

 

[ayilar]

As @Davea Lux noted, 90 octane may not be high enough. In both Poppy (my G-code Polara 'vert) and Medina (my 1971 T-code Monaco), I need to run 92+. The difference is striking when compared with even mid-grade fuel.

 

[Lefty71]

Seemingly off the subject, but since I actually had a 71 New Yorker way back in the day. The problem was never the carb for us. It was the distributor, which had that little black retard box on the side of it. We tried an Accel dual point (state of the art back then lol ). It ran like a completely different animal.

 

[70NEWYORKER]

That looks like a re-man carb..painted silver and the sticker on the rear face. Verify the rods and jest are the correct numbers for your application. My experience is reman carb can be a mix of parts from many different carbs. I have some Carter parts that don't show up anywhere in the Carter books under any Chrysler application, yet were in carbs with Chrysler numbers and sold as correct for Chrysler engines. Metering aspects of these parts were way off from Chrysler requirements.

Mount it, fire it up and see how it runs. Go from there.

 

[RWCearley]

The ethanol fuel has recked havoc on my classics. Traps moisture and rusted out fuel tanks. I know 90 octane is marginal for a TNT with high compression. So what about adding octane booster in order to get closer to 92.

 

[CBODY67]

Many octane boosters contain alcohol, which defeats the purpose of non-ethanol fuel. Many do not work as well as they claim, especially with octane that starts higher than 87 . . . according to what I read about 20 years ago.

Might be better to use 92-93+ Pump Octane fuel and add some ethanol-defeater additive, all things considered.

Concur with the state of reman/rebuilt carbs not always having OEM metering items in them. To decode the metering rod specs, there should be a chart online (from CARTER rather than Edelbrock) with the 3-step rod diameter specs.

The OEM meterieng specs usually put the cruise mixture at 14.7 to one, air/fuel ration, which is ideal for best/lowest emission combustion. With ethanol'd fuels, "stoich" is closer to 14.2 to one, IIRC. But the OEM metering should work as is, but finding the metering rods with a little bit smaller diameter might help get things to ethanol'd stoich. With new spark plugs of the correct heat range, watch the color of the ceramic, which should NOT look "crispy white", but more like very light beige after they have run about 1000 miles of so, possibly. Road miles can be best.

Back in the middle '70s, I got a Carter Strip Kit for AVS/AFB carbs. To see what might change in my '70 Monaco Brougham 383 4bbl. I figured and pondered which rods, but in general driving and with detailed mpg records, I could not tell any significant difference. But I generally stayed in the middle of things, not going "full rich" or close to it. I determined that the OEM specs worked just fine and put it back that way. This was with general driving, not racing, fwiw.

in that AVS and my '67 Newport 383 4bbl factory AFB, I could also tell no difference in using the AFB's w-step rods in the AVS or vice versa. Although the 3-step rods should have been better, I suspect.

The current Edelbrock AVS uses the 2-step rods, as does their (and original Carter) AFB.

In any event, do determine what you have as to metering items (rods, jets, and primary power valve springs color). See how it runs and as mentioned, then proceed.

Just my experiences,
CBODY67

 

[70NEWYORKER]

Part numbers:
Primary Jets 120-501 .101 dia
Secondary Jets 120-395 .095 dia
Metering Rods 16-160 .0645, .062, .055 dia
Primary Venturis (contains idle jet and both low and high speed air bleeds)
Pump side venturi 58-1273s
op pump side 58-1272s
Idle and Main jet diameters should be listed in your Service Manual as well as metering rods.

 

[RWCearley]

The carb was purchased off of ebay many yrs ago. I plan to rebuild it and check the jetting while at it. Hopefully all is well with it. 71 was a transition yr for emissions which incld carbs and ignition changes. Will attempt to sort things out when back together.

 

[MJFUR]

Here's the guy that can help. Carburetor Restoration in Youngstown, OH | Woodruff Carburetor Specialties

 

[RWCearley]

Thanks for the carburetor information. But I will try rebuilding the AVS myself. Done a few carbs over the yrs, mostly vintage European carbs, such as weber. Recently restored a pair of weber 40 DCO 3s for a 1960 alta romeo giulietta spider veloce.

The customers spider had the classic problem associated with ethanol blended fuels. The ethanol attracts moisture and the moisture clogged the small passages in one of the carbs. It took extensive work to clean the passages.

Several octane boosters use alchohol to boost octane. However a few use MMT. I will try this first. If it doesnt work I can purchase high octane fuel at exorbitant prices.

Heres some pics of recent weber restorations. Worked on other types as well. Recently rebuilt a cantankerous solex for an alfa (French thing that has no business being associated with any classic.)

 

[bigmoparjeff]

There shouldn't be any harm in running ethanol fuel if you need the extra octane as long as you don't let the car sit for long periods of time. You just need to plan ahead a bit. If the car is going to sit over the winter, it would be best to run the tank down and fill up with ethanol free in the fall. I've been working on one person's collection of cars for the last few months, and the ones that have ethanol problems were sitting for at least two years without being used. Ethanol fuel does increase the chances of vapor lock, but I've never had that issue with any of my cars.

Jeff

 

[RWCearley]

Here when they switched to ethanol blended fuels. My alfa immediately started having problems. Ultimately, the tank had to be removed and cleaned due to rusting. Ethanol will also distroy your old fuel lines.

My recent rebuild of my cosworth vega. I reduced the compression ratio from 11:1 down to 9:1 so I can use the 90 octane non ethanol. The chrysler is approx 9.75:1 so hopefully MMT octane booster will work.

 

[garyh]

Is Woodruff Carb. still offering a Club Discount ?

 

[Plymouthcustom]

The carb was purchased off of ebay many yrs ago. I plan to rebuild it and check the jetting while at it. Hopefully all is well with it. 71 was a transition yr for emissions which incld carbs and ignition changes. Will attempt to sort things out when back together.

That carb has definitely been monkeyed with, and by someone who thought it not important to save both the idle solenoid and the bracket, etc, that hold it to the carb. If you plan on using it the way it was originally intended, you need to find those parts for it.

 

[RWCearley]

It was missing more than those parts. Slowly been gathering the remaining parts through the purchase of other derelict carbs.

4968S is a very expensive carb today.

 

[Plymouthcustom]

It was missing more than those parts. Slowly been gathering the remaining parts through the purchase of other derelict carbs.

4968S is a very expensive carb today.

It was missing more than those parts. Slowly been gathering the remaining parts through the purchase of other derelict carbs.

4968S is a very expensive carb today.

Unlike most Carter carburetors made for Chrysler(they were overwhelmingly a one year only carb), this one continued to be produced until at least 1977. It was obviously deemed a replacement carb for a lot of others. The same happened for the Carter 4640S, it became a replacement for most A/C carbs, and was made for about eight ears after it first appeared in 1969.
Yours should have its original pink coloured triangular aluminum tag on it, with the carb. number and date code on it.
Most of the used 4968 carbs you will see for sale are dated years after the original ones came on 1971 model year cars.

 

[RWCearley]

Disassembled and inspected the carter AVS. The only problem discovered was a hairline crack with one of the attachment pads. From other carter AVS carbs I've seen, this is a common problem. Doesnt seem to be critical. The main and secondary jets are not marked. The metering rods are as follows: 16-546. See pics.

 

[CBODY67]

The crack you reference is NOT a design flaw of Carter AVS carbs, it is caused by "user error". How do I know this? Because I cracked the base of my 4732S AVS when using a Mr. Gasket "gasket stack" heat insulator base gasket rather than the OEM-spec thick base gasket with plastic inserts in the hold down holes.

Yes, I was trying to help a "hot restart" issue with that allegedly better gasket, BUT I was also being careful to not over-torque the hold down nuts, too. Especially as the softer gaskets in the mix, between the aluminum sheets, were quite soft. I had it all nicely done, until that last little bit of torque and than faint crack sound. Everything seemed to work ok, but I did not want things to get worse, so I ordered up a new 4734S replacement AVS. Put a new OEM-spec base gasket insulator with it.

The meterinrg rod number sounds about right, but the jets sometimes are stamped on their sides rather than on the top edges. For good measure, you might fill those cracks with some sort of aluminum-like epoxy item (i.e., JBWeld for aluminum).

Just some thoughts and experiences,
CBODY67

 

[RWCearley]

Didn't mean to imply it's a design flaw. But rather someone over torquing the nut. Might be a good idea to torque the nuts in some type of sequence and a little bit at a time. Will put type of epoxy on the crack.