Technical Question on Tuning and Choke for Rochester 2 barrel Carb

No..... I have a 2GC on my 57 Chevy which we simply added an electric choke conversion.



Mine was a 2GC which had that awful heat tube [this bolted to the side]

Your Carb is a 2G with a divorced choke so you can use this kit.
https://quadrajetparts.com/electronic-choke-conversion-1963-2bbl-rochester-p-2635.html



There are plenty of ways to wire them.
You can run a wire direct from the fuse box [they only draw 3-5a]

Some people use a relay via the Alternator idiot light wire.

In my case I used a relay from the fuse box that grounds via the oil pressure light to activate it.
This powers an electric priming fuel pump and soon as the engine starts and gets oil pressure it switches off the pump and diverts 12v to the electric choke.

^^^^ the electric choke doesn't cycle unless there is oil pressure.
It is really simple to wire if you're interested [and No fuel pump switch/button is needed]

edit: Later if you want to convert it to 4 barrel you can use an Edelbrock #1406 Carb with an electric choke.

 

I live in Riverside
I daily drove a 1973 Lincoln Continental four-door throughout my twenties back in the late '90s early 2000s (I still own the car).
I used to have problems with the FOMOCO carburetor So I bought an Edelbrock 1407 with the mechanical choke and for some damn reason I never bought the 5 dollar cable so I could have a choke... Or the electric choke conversion kit.
That semi built 460 what's the most cold blooded engine I have ever driven and I have driven a lot of carbureted cars... There was no feathering the gas
You would pump the gas three times hit the key It would start right for about 2 seconds and die You would do this over and over over until You eventually acted like the guy from "zip ties and bias plies on YouTube and went "full send" as I would pump the snot out of the gas Then held it at a pretty high RPM for probably 3 minutes before the car would finally idle... Any less than 3 minutes you would put the car and drive and it would roll about 5 ft and stall.
I had dual 2.5 straight pipes on that car with no cross over and back then I had to leave for work at 3:30 in the morning I would imagine the neighbors hated me and my car lol it was so loud.
My point to that story is you don't need a choke in California Even when it's in the high °20s (F), You just need to have the determination to keep a cold-blooded pig running.
I don't miss that job but I kind of miss driving that car especially when it was in that configuration... I have nothing to show for my twenties as it all went into the gas tank but it was fun.

 

Borg Warner used to make a kit for that. It had everything in it, lots of luck finding one now.

 

Awesome thanks! I was basically thinking the only thing that would work is an electric choke that is divorced... looks like this one would work! I should be able to figure out the wiring.

I'm going to adjust the idle mixture screws and see if the choke is even still necessary. Maybe I'm needing to feather the pedal because the mixture screws are not set correctly.

 

The wiring for an electric choke is a wire that is on when the ignition is on.

Resist the urge to use the coil wire. This really should be a seperate circuit.

Most often, I will use a relay, and a thermal breaker (self resetting).

 

Get a vacuum gauge and do that.

No telling how it is set now. Best to make sure that you know, for real.

 

Yep! I bought a vacuum gauge a long time ago to adjust something on my 53 chevy before I sold it... never ended up using it but now I have an excuse!

 

It is not hard to do, but one thing to remember: do this with the engine at operating temperature, or your mixture/idle will be off when you get up to it!

 

Thanks! I'll definitely do it with the engine at operating temperature.

 

I have a complete setup from a 72 C10 at the shop. I can pull it and stick it in the mail if you need it

 

Actually I'm not sure if it's the same as yours...

 

Oh interesting!! When I looked up the block codes on the engine in my c10 I traced it to a 1975 C20 engine... the previous owner put a 350/TH350 in it.

 

If this will work for you it's yours. I don't have the heart to throw shit away lol, I always feel like somebody might need it

 

Oh awesome I'll tune the mixture screws later today and see how it feels without choke and circle back with you. Thanks so much for the offer and thanks for the great advice on glass for my 50 shoebox ford in my other thread!

 

"Also given no choke how would I adjust the carb mixture screws? Would I need to do that some particular way once the vehicle is warmed up enough? I read some ways to do this include adjusting until you hear the rpm change, then doing the other one."

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I am still learning how to use the hamb chatbox So pardon me if I butched your quote because I deleted a good portion of it I don't know if I'm supposed to do that or not...
anyways.

You're idling problem when cold is almost definitely choke related sounds like that Lincoln I mentioned yesterday) It has nothing to do with the mixture screws If it goes away once the vehicle is warm. For that you will need to hook up a choke of some sort.
I'm going to let the other guys tell you about your carburetor because I am unfamiliar with your particular carb but I definitely know The basic fundamentals of "antique" automobiles (the pre-computer era).
Here is a real simple way to adjust your mixture screws that works pretty good for "doing it by ear" (mind you this is not an oscilloscope or a technical way to get maximum horsepower or fuel mileage It's just to make the car run good There is a lot more variables in tuning if you want to get real precision but this will get it in the ball park and should Make the car run good once it is warm.

This advice goes for any engine that has a carburetor,
First get the engine properly warmed up in the case of a classic car engine that's usually around 180° F.
Next carefully turn the mixture screw clockwise and count the turns until it comes to a stop so you have a baseline number. DO NOT, I repeat do not crank down on the screw you're not tightening it up all you are doing is counting how many turns it is turned out. If you tighten it you damage the tip of the mixture screw as it is a needle point generally speaking and is usually made of soft brass or is going into a brass jet. You just want to lightly bring the screw closed until it comes to a stop (no torquing on it at all). Usually this is a turn and a half to three turns It just depends on the car, very rarely it may be more or sometimes it may be less, If the screw is way far out (let's say five or six turns or better) It will cause the mixture to be rich and at that point it pretty much isn't doing anything other than plugging a vacuum leak. If it is really far in It will be a potential lean condition.
If the screw is way far out is it good assumption the jet ( where that needle screw seats into) is probably plugged or the wrong size but that is a whole other can of worms that's hard to explain in a few paragraphs and we will worry about that kind of worms if I'm ever asked and even then I'm not probably the best person to explain it but I digress.
Going back on the proper subject of how to adjust your mixture screws:
After you count the turns reset the screw to the original position where you found it unless when you started you found it and the screw was more than three turns out or less than 3/4 of a turn in If that is the case back it out (or turn it in) until it is about 2 turns (again every car is different but this is a good baseline for most engines even lawn mowers). Start the engine then go out to the carburetor and safely get a screwdriver onto the mixture screw and slowly crank the screw clockwise until the engine shows a slight stumble immediately stop then reverse your rotation backing the screw 1/2 of one turn (counterclockwise) from the point where it stumbled. That mixture screw is now pretty well set.
Agian it should be one half turn backed out past where it stumbled. Some carburetors have two mixture screws if this is the case with yours repeat this same process for the second one (some four barrels I have messed with in my lifetime The one on the passenger side (right side of the car) seems like it doesn't do anything because you can't get it to stumble or change idle or anything when you crank it in or out I usually set that to match the one on the drivers side of the carburetor, If it stumbles when you're moving the screw in then you know to back it out one half of one turn It doesn't do that again just set it so it matches the other one That will be good enough.
The big key is the 1/2 of 1 turn backwards from when it starts to stumble This goes for pretty much every single carburetor ever made other than some weird goofy things that most of us won't come across in our day-to-day travels.

To explain the mixture screws If the screws are too far out the engine will run rich and It will probably seem like it runs okay (almost unnoticeable in most cases) but it is technically running too "fat" so to speak. So it is wasting fuel making excess emissions and potentially fouling out your spark plugs plus creating carbon all over the valves The piston tops combustion chambers and even the exhaust ports downstream how rich is it depends on the engine sometimes it is almost unnoticeable other times you will actually see the black soot come out the tailpipe either idling or when accelerating.
If the mixture screws are too far turned in generally speaking it will not want to accelerate It will not want to idle and it will generally be just a finicky pig so much so you'll be ready to smash the carburetor with a hammer running lean is always a bigger pain in the butt for an engine that running rich.
Also running lean can cause really weird things to happen like for the engine to run warm, to have a bog or flat spot in the carburetor on acceleration (almost like a bad accelerator pump). Basically a lean running engine drivability is really affected whereas a rich running engine It usually isn't noticeable unless it's really bad.
Anyways I hope that helped I know my comment is really long and I don't think I explained it as well as it needs to be explained to somebody that has never done it.
Edit:
I definitely should have not have butched your comment trying to quote it
Also when I say driver's side I mean the United States driver's side (when sitting in the car the left side) and the United States passenger side (when sitting in the car the right side), I just realized your comment is from New Zealand so there's a good chance you're steering wheel is on the other side so my comment may confuse you.