Finally - a carburetor question!

Dear Car Talk

Dear Car Talk | Dec 01, 1999

Dear Tom and Ray:

I have a 1981 El Camino with a 305 engine and a four-barrel carburetor. This car takes about 5 to 10 miles to warm up and run smoothly, although the heater starts
working much quicker than that. When I try to accelerate before the engine fully warms up, the speed increases some, and then goes flat. I can get a slow, steady
acceleration if I hold the gas pedal to the floor. After the long initial warm-up, the car runs well with good acceleration. Any ideas? --Cloyd

RAY: Wow! This is exciting. We've been waiting years for a chance to use this answer again.

TOM: This used to be our favorite answer. But with carburetors going the way of my brother's hairline, we haven't had a chance to use it in ages.

RAY: You need a new choke pull-off, Cloyd.

TOM: Carburetors have chokes to "choke off" the air and, in effect, make the mixture rich (gasoline heavy) when the car is cold. This helps the engine get started when
it's ice-cold.

RAY: But if the mixture STAYS too rich after those first couple of minutes, then the engine can't get enough air to drive at high speed, and it'll run poorly, bog down
and not accelerate well. This sounding familiar, Cloyd?

TOM: So immediately after the engine is started, a device called a "choke pull-off" begins to release the choke part way. Your choke pull-off isn't working. And the
reason your car eventually begins to run better is because another device -- the choke thermostat -- takes over after a few minutes and pulls the choke open completely.
After that, everything is fine in your car -- until the next cold start.

RAY: What you need is a mechanic old enough to have worked on carburetors. If you find such a guy and describe these symptoms to him, he'll have it fixed in half an

TOM: Poke around some garages. And when you find an old geezer with his teeth soaking in a glass of carburetor cleaner on his workbench, you'll know you've found
your man.

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