Hi again could you tell me why is there a choke and throttle pull **** on my truck.I understand the choke is to help start the engine.But what does the trottle **** do.When you pull it out does this keep the engine running at a steady speed.But i thought thatS what the choke does.So when i start the engine from cold do i pull the choke out,but when do i use the throttle pull. And when do i not need it.Thanks Pete UK

 

Throttle ****: Manually operated 1930's thru the mid 1950's version of today's Cruise (Speed) Control system.

The original idea was that the driver didn't have to keep his foot on the gas pedal on long trips.

Later outlawed for obvious safety reasons.

With a modern cruise control system, just a light tap on the brake pedal dis-engages the cruise control.

But that does not work with a throttle ****.

The further you pull out that ****, the faster the vehicle goes, and in a panic situation, most ppl forgot to shove in that ****.

 

Cheers. Now i understand thank you.

 

Another use of the throttle....

On the larger trucks with Power Take Off (PTO)... used to bring the engine speed up when or if the load on the PTO unit requires it.

I will agree also on the cruise... and how it could be hairy in situations

 

Well with the throttle cable explained (and I also used it to keep the engine at RPMs higher than idle to perform certain tune up functions), let me explain the choke cable function (if you know this already, please forgive my redundance).

As you know, internal combustion engines that use a gasoline and air mixture are dependent on the correct ratio of gas to air to run properly. When the engine is cold, or colder air temperatures exist, the air is slightly concentrated and contains more oxygen per unit volume. Thus in order to correct the ratio of gas to oxygen the choke is used.

What happens when you pull the choke cable is the upper plate on the carburetor throat is closed (in varying degrees) to restrict air flow into the carburetor. This results in the vacuum pulling more gas and less air into the mixture - making the cold mixture "richer."

This not only helps the engine to run properly, but prevents damage (from pre ingnition[pinging] and backfire) from too lean a mixture in a cold engine.

But also, when the choke cable is pulled, an excentric cam plate on the side of the carb is rotated which engages the "fast idle set screw" and opens the throttle plates slightly more - causing the engine to idle at a higher rpm - usually about 850-1000 rpm depending on the amount the cable is pulled. The fast idle pulls more of the richer mixture into the engine to combat the cold conditions and help the engine to run at a decent idle.

You will notice that as the engine warms up, the idle rpm will tend to increase if you don't push the cable in a little. But also eventually, the engine will run badly because it is running too rich (flooding).

One interesting point about manual choke cables is this: If for some reason, you can not get your truck to shut off when you turn the ignition off and it sits and diesels (usually due to timing issues or bad gas) you can get it to turn off if you pull the choke cable fully out. That will cut off the air.

I know this because of something that happened to me. In typical female fashion, I forgot to stop for gas one day and ran out on the highway. A very nice older gentleman stopped immediately to offer help and soon had his spare gallon of gas in my truck. I was very quickly presented with the fact that he had put a gallon of diesel fuel in my truck and as I pulled into the closest gas station knocking and pinging, the engine would not stop running when I secured the ignition. It sounded like it was going to explode. Had to pull the choke out all the way to get it to quit.

When starting a cold engine, press the gas pedal to the floor and release ONE time. While it is down pull the choke cable out about half way. This will set the choke plate, allow the cam to rotate under the fast idle screw and cause the accelerator pump in the carb to shoot raw fuel into the manifold. When starting the engine do not pump the gas pedal or you will flood. Foot off the gas and the engine should start right up. If it idles too high, push the cable in slightly. You will eventually get a feel for the right choke setting for you truck in various tempuratures. Don't forget to push in tha choke after you are up to operating temp, or your mileage will turn to yardage!

Cheer-e-o!!!

J!

Y

 

The throttle **** was also used to help the truck warm up in cold weather and to run the engine at a higher rpm to help the generator to maintain the battery charge. Work trucks would often spend a lot of time running at idle or with the headlights being used as work lights on a job site drawing down the battery. When the headlights started to dim you would pull out the thottle **** until they brightened again.

 

An old farm truck loaded with bags of fertilize would be a rough ride across a plowed and tilled field......the farmers would pull the throttle **** a little and leave their foot off of the pedal so that it would move slowly and steadily across the field.
I've also known farmers to pull the throttle **** to get the RPMs up a little when they are about to tow something.....why I don't know ...but that's what they'd do.

 

I remember as a kid on the farm if we were picking corn I would steer my Dad's '48 Chevy 3/4 ton 5 window cab pickup. Since I was too small to reach the pedals Dad would pull out the throttle **** so the truck could keep the right speed. As I got older we would set the throttle and the truck would "steer" itself in the rows or furrows of the field and I was out helping to pick corn or collect rocks or whatever we were doing.

I also used the throttle ***** of the Fords I drove when I delivered lumber if the truck had dump bed or a high lift bed that ran off the PTO as mentioned earlier.

 

Useful little bugger wasn't it?

 

Don't know about you guys, but I get James Dean Nightmarish catostrophic visions of that **** pulled all the way out on a dark desert Hiway...

 

.....cool wind in your hair?

 

Exactly!!...cruise control??...that's scary! ,though I completly understand that's how things were
What is a "collita" anyway?..I suspect something close to the aroma of flowering Sage...