Re: {Chrysler 300} Electric chokes on 2903S carbs?

Hi John,

I should have been more precise with my wording about the choke unloader issue. I believe the spec for when the choke "snaps shut" when you blip the gas pedal before starting the cold engine to set the fast idle cam and squirt gas into the carb from the accelerator pump is something like 3/64" open between the choke valve and air horn (set by bending choke connecting rod), but when the engine fires, the choke unloader needs to increase that opening to 1/4" to let sufficient air in and not keep too much choke in effect once the engine is running. If there is too much pressure exerted by the choke spring, or if the operation of the unloader is not what it used to be due to wear of the bore or the unloader piston itself, it won't generate enough force to pull back the choke plate/valve to the full 1/4" open, thus starving the engine of air and leaving the mixture too rich after initial start. I've had to fiddle with the choke spring setting to make it strong enough to get to the 3/64 closed position, but just barely, so the unloader is able to pull the choke plate open a full 1/4" once the engine starts. That, in turn, can also lead to the choke opening up too quickly/soon as it heats up, which can cause hesitation until the engine has reached full operating temperature and the choke has opened all the way. Everything is a bit of a compromise, but then again, these cars seem to run pretty darn well even when set up 'plus or minus a football field' as long as there is fuel, air, spark, and compression at around the right mixture and all happening around the right time. I'm no longer trying to squeeze the last 0.1sec off my 1/4 mile time or trying to win the Mobil economy run.

I don't have that problem on the Hurst AVS, as the external choke pull off diaphragm generates plenty of 'pull' to open the choke plate to spec after initial start up. I did have to put a new one on a few years ago, due to a leak in the original diaphragm that wouldn't pull the choke off properly.

I guess these various issues are what has led many owners of old carbureted cars to add EFI systems in recent years? I still prefer to tinker with my old carbs. Keeps the brain active! ;-)

On Tue, Nov 11, 2025 at 5:31 PM John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:

l bought Edelbrock kits for afb to do this on an F . two years ago
I had made a very bad mistake , put J type manual choke on my F but more to that than it looks — as if you just “hook it” up , you have to release pressure on high idle cam by tapping gas to move choke (too long to get into has to do with free play slot and linkage to high idle cam , parts not there ) High idle cam if on a step locks up choke is result
Anyway fuggetaboutit

Have not done the E choke yet on that car .Looks ok with some cobbling up TBD

But I found out that a ? Chinese kit on ebay or amazon at 1/2 the price of Ebrock is just as good, Bought two of those for another car to be built .

But since then found out / decided AVS is flat out a far better carb , than our original or afb , and can come with electric choke , may need some machining on ram —- tbd

So — Ill tell you what I did on baby hemi to dump the WCFB , used a 3/4” aluminum carb spacer for AVS adapted to the wcfb bolts, ( flatheads under gasket) then machined out dodge intake to wide open plenum got rid of the wcfb holes . However got carried away broke into exhaust heat hollow around plenum. Almost had to , anyway as AVS large secondary throttle discs hit hogged out dodge plenum wall no room ( wcfb in dodge is tiny ) Had to fix ( angled copper sheet piece 4/40 screw and copper high temp permatex rtv thin bead at edge to seal up . ( stuff IS tough) Also sealed exhaust heat from head port at port same way , copper disc in port and rtv
Then took page from 400 hp F drilled the spacer sideways for water passage , 3/8 hoses , on idle side of spacer — so have “ air gap “ manifold water heat under idle side , E choke AVS on little dodge . Came out great big plenum.

AVS IS totally bulletproof , 2 generations ahead 20 years after our stuff — a HRM dyno guy measured AF ratio idle to 6500 perfect out of box , got 650 hp out of 460 ford , sensors in each exhaust port .One AVS , 950 I think ( we would use 2,550 or 650 ) They were amazed at carb “ better than FI “

Carl has electric chokes on J, perfect , but I think an AFB swap ?

On F with two AVS — to do right , bell crank gotta go , some kind of dual cable pull ( Lokar?) so you can set idle by idle stop separately in each carb .2903 has air valve , not idle stop . You match turns open . MAYBE the bell crank with one adjustable end and connect after setting both idle stops . ? need air flow thing ( sync thing for british carbs) to match idle air flow? all TBD but doing that on next ram build
Time catching me , but way I would go . Carbs computer designed now ( AVS ) millionth inch type stuff on AVS , now from E brock , computer profiled venturi etc to make “ air valve secondary” gives perfect AF ratio at any air flow ( self adjusts valve to cfm need) They did that over emissions,,we benefit
Interesting stuff, ymmv
John
ps on original setup , it never closes fully , ? you put a certain size drill in there at room temp sets up choke . Not fully closed ever = flood risk . Flooded ram hard to clear , really embarrassing( laugh)
On Nov 11, 2025, at 4:05 PM, John Nowosacki <jsnowosacki@xxxxxxxxx> wrote:

I have toyed with the idea of the electric chokes on my 2903S carbs, as it doesn't look like too much of a job given that the round covered area where they go is provided on the original carbs, even though the well type choke is what is installed in the ram intake manifold.
I haven't done it because I have the original setup installed and adjusted 'well enough' that waiting about 30 seconds on fast idle is about all it takes to blip off the highest point down a notch or two to save the transmission bands. The biggest problem I have with my 2903S carbs is the choke pull-off function upon start up. I think the 'cylinder' that the little piston sits in is no longer perfectly round and therefore has a bit of a bypass leak, which prevents the piston from pulling against the choke spring at startup with sufficient force, making the mixture too rich at first. I had to adjust the bimetallic spring tension on the chokes so that they don't 'snap' shut when cold, but just barely get closed so the now-weak vacuum action on the choke pull off piston is sufficient to pull the choke back open to the proper specification once the engine starts. Other than that, the warm up takes place fast enough that both chokes are open in a relatively short time, even if not at exactly the same rate. I'd be more likely to make the change if the car was used as a daily driver in a climate with wide temperature swings between summer and winter. For the kind of fair weather, relatively infrequent use my G gets (2000 miles per year or so), I can live with the original pieces.
I wish they had 'external' choke pull-offs like the AVS on my Hurst, as I would just put new ones on if they were 'weak' or worn. Any other suggestions for getting full pull off action on the originals on the 2903s would be appreciated.

On Tue, Nov 11, 2025 at 1:06 PM Nick Taylor <nicksgaragesd@xxxxxxxxx> wrote:
Had anyone installed electric chokes on the ram induction 2903S carburetors?

A friend has two 1960 ram cars and he's convinced he needs electric chokes.

Didn't find anything in the tech archives.

Nick

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