Carb.Questions

[gary]

Hello All: I am thinking of replacing the carb on my '71 GTX 440.What is available that fits stock intake , Air cleaner & linkage?
Edelbrock? Any thoughts? Currently have a Rebuilt Carter AVS 4968s.Anyone running that carb? Thanks , Gary

[EL5beepbeep]

Well there is a wide variety of carbs you can use and a lot depend on your intentions. The 4968S AVS was the standard HP 440 carb offered in 71 from mopar so from a stock appearing standpoint that is pretty much it.

The intake is a square bore pattern so it can take any square bore carb without a problem. Linkage may need some minor tweaking, but there are adaptors made for most applications.

What intentions do you have? Reliability, more performance, mileage, etc.

[gary]

Hi,The answer is Reliabilty.
I had the car out today. (90 Deg.)In Traffic,it started to miss,Backfire through Carb. and died would not start till' an hour later.Now i don't trust the car.It is mostly stock W/Chry.Distributor& elect.ign.module That is a couple years old,Accell coil is a few years old.I think it was Vapor lock.I use Non Ethanol gas But i know today's Gas is Garbage.Does it sound like a carb problem or Ignition system.It was hot under the hood but not overheating.Thanks in Advance Gary '71 GTX

[EL5beepbeep]

It does sound a bit like vapor lock.

If so a new carb of any type may not help you too much.

By far the best fix i have found for vapor lock is to have the fuel return line setup that was actually standard on 440 and 426 models from 71 onward. It features a 3 nippled vapor separator in place of the fuel filter located next to the fuel pump. It had return tube with an orifice in it that would plumb to a 1/4" steel hard line that would return the unspent fuel vapors to teh tank.

Come to think of it if your car is stock it should already have this. If not you need the vapor separator, the 1/4" return line, and a sending unit with 2 nipples (one for fuel out usually 3/8" and 1/4" return).

I placed this on my 383 in my super bee and it was a huge help with vapor lock.

In regards to possible carb choices do you want to retain the stock choke? That will limit your options considerably to be honest.

[gary]

Hi,I do have that 3 Nipple seperator near the fuel pump and new rubber lines Fuel tank & hp stock pump.I want to go with an Edelbrock that will bolt on to Fac.intake and able to use stock Air Clnr. & linkage if possible,It can be Elc.choke too.What is the Carb.that works the best for street use?Any model numbers? Best place to buy? Thanks for the help , Gary

[EL5beepbeep]

Hey Gary,

Well that is good that you have the vapor separator system. Sorry to hear that you still have issues.

The edelbrock Thunder AVS series is probably the closest to a stock replacement for your AVS. They come in manual or electric choke. I am not sure if the manual choke setups will connect to our stock thermostatic choke, but electric chokes are pretty easy to adjust. I am not real familiar with them to be honest, but I have scene them on a lot of rebuilds lately. Like anything I am sure they will need some tweaking to run right. I personally prefer the holley style carbs and am a bit more familiar with them.

For the 440 I would definitely go with the 800 cfm model.

In regards to your current 4968 AVS I have been looking to use one on my 383 as a sort of "day 2" modification. If you are serious about getting a different carb and no longer have a use for it I would be interested in purchasing it from you. Something to consider.

[71bird]

Question, what does everybody think is causing his problem? Vapor lock? I never had any problems when I was driving my car in 74-78. 383 AG, holly carb.Is it just the gas today?

[EL5beepbeep]

I think it has a lot to do with the gas. For the most part most of the country now runs an ethanol blend due to government mandates. Like oil there are a lot of additives that are no longer used due to emissions purposes or for the simple reason that 99% of whats on the road is fuel injected which runs under a much more pressurized system.

I do know that the ethanol blends are much harder on carbs. IF the car sits for 4-6 months without running you will begin to have issues with deposits and varnish. IT has really been problematic on small engines like snowblowers and lawn equipment. You have to use stable and I always run the carb dry when I use my blower. Our cars are almost the same since we use them sparingly.

As for boiling point the ethanol blends oil over sooner and are much more prone to vapor lock. For that reason alone I put the stock style return system in my other car. I have not done it to the roadrunner yet, but I think I will because I am having hard starting issues after it sits from a short ride.