Carburator Question

[davbell22602]

I'm getting 2 quadajets for cost of shipping for a 4bbl 390. One is manual choke and other is a vacume choke or hot choke carb.

What is vaccum carb? What is a hot choke carb?

Both need cleaned, overhauled, and rebuilt.

 

[Manbearpig]

Theres a spot on the passenger side of the intake that connects to the choke of the carb

Heat rises out of that spot on the intake into the choke and the choke opens

 

[davbell22602]

Theres a spot on the passenger side of the intake that connects to the choke of the carb

Heat rises out of that spot on the intake into the choke and the choke opens

Thanks

 

[89Suburban]

IMO, a vacuum choke is a setup where there is a manifold mounted choke thermostat coil that is linkaged to the choke butterfly on top of the carb. Then there is a small diaphram unit, kind of like a super mini air brake chamber, that once the engine is started, vacuum pulls on the diaphram to partially open the choke once running. Kind of like a balanced tug-o-war between the choke thermostat and the vacuuum diaphram. For just the right combination to make the engine run right during cold startup.

Then the hot choke setup is a carb mounted choke thermostat coil in that round little plastic housing on the side of the carb, that instead of an electric current heating the coil to expand and open the choke, like on newer versions of the electric choke, there is a heat tube, running from the intake manifold to a port on the choke thermostat housing to feed hot air to heat the coil and make it open the choke.

 

[Swims350]

never seen or heard of either.

 

[HotRodPC]

I'm getting 2 quadajets for cost of shipping for a 4bbl 390. One is manual choke and other is a vacume choke or hot choke carb.

What is vaccum carb? What is a hot choke carb?

Both need cleaned, overhauled, and rebuilt.

Theres a spot on the passenger side of the intake that connects to the choke of the carb

Heat rises out of that spot on the intake into the choke and the choke opens

Yep, that part MBP is talking about is often called a choke stove. And it sets above the hot water crossing in the intake. Also aka hot water choke. So if you use that type, don't block off your water passage completly or you choke will have a problem of coming off when the motor is actually warmed up.

 

[bucket]

It actually uses heat from the exhaust crossover in the middle of the manifold. It also heats the bottom of the carb to keep it from icing up in the winter.

Ever notice how the old 283's, 327's and whatnot always have the paint burned off the intake on both sides of the carb? It's from the extreme heat in that part of the manifold.