4 Barrel carburetor help.
02-11-2013, 10:38 AM
#1
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4 Barrel carburetor help.
Ok its me againn. I am looking at some 4 barrels and im just wondering how its going to end up working with my Engine. My stock 2 barrel carb looks like the choke is ran of of maybe vacum and has a tiny rod going down into the intake. all of the Holley 4 barrels i have seen are either electric choke or manuell. Now im no fan of running stuff through the firewall so that cuts out the manuel choke. Now for the electric choke how does this work?
http://www.summitracing.com/parts/hl.../make/plymouth
This is the Carb im really thinking about getting if i can find out how the electric choke works. My choke flips up and down when i press on the gas peddle. Needing help before i make this purchase.
Thanks again.
http://www.summitracing.com/parts/hl.../make/plymouth
This is the Carb im really thinking about getting if i can find out how the electric choke works. My choke flips up and down when i press on the gas peddle. Needing help before i make this purchase.
Thanks again.
02-11-2013, 06:22 PM
#3
You can download info at Holley's and Edelbrock website. Basically the Holley/ Edelbrock electric chokes are a modification of the same round black "can" choke that has been around since before I was born, and I'm old. It has been known on just about every U.S. carb I can think of, including Ford/ Autolite, Carter, Rochester, Holley, and etc, etc.
This consists of TWO parts in the can.
Originally, "before electric" the black round type chokes had a tube that ran down into some sort of passage in either the intake (V8) or exhaust manifold. This did not enter the exhaust passage, but rather was a separate passage. The other end of the tube was typically connected to a port on the carb or air filter, merely to let in clean air.
Inside the assembly, is a vacuum piston. The choke housing is connected to intake vacuum, which does two things----it sucks the piston to one end when the engine runs, and it draws air through the heater tube.
The piston "breaks" the choke open a set amount, and is and does the same thing as a separate diaphragm choke break on your original "linkage" that you describe.
On these electric chokes --which are a compromise--- engine heat has been replaced with an electric heater coil run off 12V whenever the key is in "run."
In both cases, the heat warms the choke thermostat which eventually moves the choke linkage to open.
All of these "round" type chokes can be loosened and turned to compensate for a leaner, more cold blooded engine, colder/ warmer climates, etc.
Your original choke works exactly the same way, except in this case the mechanical choke thermostat is in the well down in the intake manifold, and instead of a "choke break" piston, there is a separate small vacuum diaphragm on the carb, connected to manifold vacuum
This consists of TWO parts in the can.
Originally, "before electric" the black round type chokes had a tube that ran down into some sort of passage in either the intake (V8) or exhaust manifold. This did not enter the exhaust passage, but rather was a separate passage. The other end of the tube was typically connected to a port on the carb or air filter, merely to let in clean air.
Inside the assembly, is a vacuum piston. The choke housing is connected to intake vacuum, which does two things----it sucks the piston to one end when the engine runs, and it draws air through the heater tube.
The piston "breaks" the choke open a set amount, and is and does the same thing as a separate diaphragm choke break on your original "linkage" that you describe.
On these electric chokes --which are a compromise--- engine heat has been replaced with an electric heater coil run off 12V whenever the key is in "run."
In both cases, the heat warms the choke thermostat which eventually moves the choke linkage to open.
All of these "round" type chokes can be loosened and turned to compensate for a leaner, more cold blooded engine, colder/ warmer climates, etc.
Your original choke works exactly the same way, except in this case the mechanical choke thermostat is in the well down in the intake manifold, and instead of a "choke break" piston, there is a separate small vacuum diaphragm on the carb, connected to manifold vacuum
Last edited by 440roadrunner; 02-11-2013 at 06:24 PM.
04-20-2013, 09:58 PM
#5
The electric choke is a bimetal spring that opens via heat. Not sure where the piston 440 rodrunner is talking about comes in.
Runs off the power wire coming from the field of the alternator OR the purple/blue wire that supplies power to the ballast resistor. Later models had a three pin oil sending unit that used oil pressure as a switch for when it could go on. Not very good though.
70-80's chryslers have a thermostat control that mounts to the intake. It just cuts off power when the engine is hot so that full voltage is no longer used on the electric element. On all the time burns them out so it's a good idea to install one. Mid 70s cars had electric assist choke heaters and so did some mid 80s.
Ive wired in a few but I prefer the original choke instead as the electric ones do unbolt and can be easily replaced with a proper choke.
Runs off the power wire coming from the field of the alternator OR the purple/blue wire that supplies power to the ballast resistor. Later models had a three pin oil sending unit that used oil pressure as a switch for when it could go on. Not very good though.
70-80's chryslers have a thermostat control that mounts to the intake. It just cuts off power when the engine is hot so that full voltage is no longer used on the electric element. On all the time burns them out so it's a good idea to install one. Mid 70s cars had electric assist choke heaters and so did some mid 80s.
Ive wired in a few but I prefer the original choke instead as the electric ones do unbolt and can be easily replaced with a proper choke.
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