68 street Hemi carb questions

[vitamin c]

I just picked up an original 68 Charger RT Hemi 4 speed, and have some questions on the correct operation of the choke and AFB carbs. The rear AFB 4431 has been modified to an electric choke, and I'm trying to get it back to the correct 1/4'' heat tube/tubes. currently I only have one tube that is broken at the manifold. looking at year one, they have a two tube set. Is there suppose to be two tubes? the manifold has a pipe plug on the bottom side that I assume should have some type of brass flair to accept a second tube, but im still confused on where it attaches to the choke itself. I have ordered the tube set and complete choke assembly.
Second, it appears I am missing the dashpot. What operates the dashpot, 12V power?? or vacuum???
third, I see reference in the service manual of a distributor vacuum control valve. Am I missing that also??

 

[62MAX]

Here is what you need,no vacuum or power to the dash pot,actuated by arm on throttle shaft.

 

[Meep-Meep]

Any heat tube type choke must have essentially a complete circuit - meaning the ambient temp air enters the exhaust manifold from the carb air horn (or in the case of the hemi, the small nipple in the base of the air cleaner) and ends up at the choke bimetal spring. It's important that tube going through the exhaust manifold is not rusted to the point of leaking exhaust gas into the choke unit.

 

[vitamin c]

Here is what you need,no vacuum or power to the dash pot,actuated by arm on throttle shaft.

Got it. I see you have one choke tube entering the plastic housing and nothing attached to the fitting on the bottom of the spring housing. I don't have the parts ive purchased yet, but the tube kits that the after market sells appears to have two tubes. Is it a case of use the one you need? The broken tube I have attaches to the aluminum spring housing and top the top side of the manifold. I also see you have the vacuum control valve. is that correct for a 68?

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Any heat tube type choke must have essentially a complete circuit - meaning the ambient temp air enters the exhaust manifold from the carb air horn (or in the case of the hemi, the small nipple in the base of the air cleaner) and ends up at the choke bimetal spring. It's important that tube going through the exhaust manifold is not rusted to the point of leaking exhaust gas into the choke unit.

Boy, Ill have to look, but I don't recall any fittings/nipples on the base of the air cleaner. My tube is broken off of the steel fitting pressed into the top of the exhaust manifold, and I do hear an exhaust leak "tick" when the car is running. I believe the kit I've purchased come with the new press in manifold fitting. are you saying that fitting in the manifold is sealed from exhaust gasses?

 

[Meep-Meep]

Got it. I see you have one choke tube entering the plastic housing and nothing attached to the fitting on the bottom of the spring housing. I don't have the parts ive purchased yet, but the tube kits that the after market sells appears to have two tubes. Is it a case of use the one you need? The broken tube I have attaches to the aluminum spring housing and top the top side of the manifold. I also see you have the vacuum control valve. is that correct for a 68?

- - - Updated - - -


Boy, Ill have to look, but I don't recall any fittings/nipples on the base of the air cleaner. My tube is broken off of the steel fitting pressed into the top of the exhaust manifold, and I do hear an exhaust leak "tick" when the car is running. I believe the kit I've purchased come with the new press in manifold fitting. are you saying that fitting in the manifold is sealed from exhaust gasses?

Yes! It must be or your choke unit will be carboned up and destroyed. That tube is a heat exchanger only. The air that is drawn into the choke assy by the vacuum that operates the pull off piston is heated as it passes through that tube. Some carb models have a 1/4" long nipple from the air horn, which is the fresh air inlet for the choke.

 

[vitamin c]

I have found some pictures of the dual choke tubes and am starting to understand how this works. I have received the tubes and stainless manifold "heat exchanger" from year one, but of course the choke parts are back ordered. I do see that the "heat exchanger tube is hollow, so i'm still a bit confused on how it exchanges . I am missing the correct fitting that threads into the bottom of the manifold, the clips that hold the tubes to the back of the intake, and I have not looked at my air cleaner base or rear carb to see where/how the tube attaches with the rubber hose. You can find the clips on flee bay, but I cant find the manifold fitting.

 

[62MAX]

If you want the right information,call John Arruzza - 919-918-7584 then you will know for sure !

 

[vitamin c]

Thank you, I may have to do that. I did look at the air cleaner base today and it does have the nipple for the tube hose. Now I just need the choke parts and locate the correct fitting for the bottom of the exhaust manifold

 

[Meep-Meep]

I have found some pictures of the dual choke tubes and am starting to understand how this works. I have received the tubes and stainless manifold "heat exchanger" from year one, but of course the choke parts are back ordered. I do see that the "heat exchanger tube is hollow, so i'm still a bit confused on how it exchanges . I am missing the correct fitting that threads into the bottom of the manifold, the clips that hold the tubes to the back of the intake, and I have not looked at my air cleaner base or rear carb to see where/how the tube attaches with the rubber hose. You can find the clips on flee bay, but I cant find the manifold fitting.

The section of tube on the air cleaner side is cold air entering the heat exchanger tube. Hot air exits on the carb side because that heat exchanger tube inside the manifold is being blasted by hot exhaust gases. The result is like heating the inside of the black choke housing with a heat gun or hair dryer (not exhaust gas). Engine vacuum draws the air through the circuit.