The Stovebolt Site Forums The Shop Area General Truck Talk Choke/Throttle

I was wondering why some of the early Chevy trucks had a choke cable and throttle cable what was the purpose for this ? Any info would be appreciated .


Thanks

The choke was for cold starting conditions and the throttle would hold the engine rpm at any desired level. The long intake manifold on the inline six made the engine "cold blooded" and required a richened fuel/air mixture till warm. The choke could set how rich the fuel mixture was. For cold starting you pulled the choke all the way out till the engine fired and then slowly pushed it back in as the heat built up. If you wanted to go back in the house till the heater got working you had the choke about half way and set the throttle so the engine run fast enough to keep from dying. The throttle should NEVER be used for cruise control. After hand chokes they went to automatic chokes and now to computers.

Throttles were not used often. Pulling the choke, automatically stepped up the low idle. However, we used the throttle on our fuel delivery trucks when we used the PTO pump.

Thanks for the info guys, That makes sense and answers my question.


Thanks

I would have trouble without my Throttle cable. When I start, my right foot goes to the starter pedal and my right hand uses the throttle cable to get the revs up.
Also great at a stop light on a steep hill when someone decides to sit on your tailgate. You have one foot on the brake, one on the clutch and you have to be quick to lift it off the brake to get to the gas before you roll back. That is also where it comes in handy.

I will add a third time when it is handy. When you want to run the engine for a while without it discharging, the throttle is the way to go.

Here’s a fourth

Plant the front tires in a plow furrow in the sugar beat field, put the 4 spd. in first (creeper gear) pull out the throttle to about 2000 RPM. Then get out, walk along with the truck while pitching sugar beats into the bed

Those are all great scenarios that I would never thought of, I guess there is a real good purpose for both cables.

Ahhhh... The infamous GMC robot harvester! Thought that was just a rumor. :-)

Also, out in the field....Put the truck in first gear (granny) pull out the throttle a little, jump out of the truck and climb in the bed to throw hay out for the cows.

On a steep uphill pull in the summertime, set the throttle wide open in whatever gear it takes to pull the hill at walking speed or so, then climb out on the running board to steer and get away from the heat inside the cab. I've seen pictures of big rigs pulling the Grapevine Hill in California that way.
Jerry

I also believe that one of the intended uses for the throttle knob was running PTO equipment. All the AD 4 speed trucks have the side plate on tranny for mounting a PTO, not sure about the 3 spd's.

An excellent time to put the spigot to use as well, draining spent coffee. On the 250 HP, 88,000# GVW semis I started on, there was no shortage of opportunities to get out. Sometimes you could walk faster than the truck was going..

I used my throttle cable to inspect my truck while it rolled down the road as it was only going slowly it let me walk around it while I looked it over top to bottom to see if all things were correct and working properly.

When I drove my 52 in the winter I'd get it started in the morning by using the choke as normal and as soon as possible push the choke all the way back in, set the throttle to run at a fast idle, then turn on the fan/heat. Go inside for breakfast and come back out to a nice and warm and defrosted truck.

I tried the throttle knob as a cruise control on long trips, it's not worth the trouble, and probably not all that safe or recommended either. Even in the mid west in the long flat and straight roads you still need to constantly adjust the throttle ever so slightly, so no point in using the one in the dash.

Grigg

You wouldn't happen to have a copy of those pictures, would you? That sounds like it'd be interesting to see.

Nope, they were on the wall of the office of a trucking company I drove for in California. Back in the late 40's and early 50's, 30 years before my time as a driver, Grapevine was a real challenge, 2-lane road in some places, lots of switchbacks, and "slow truck" lanes on the really steep parts. The big rigs were either running BIG gas engines, or some of the early Diesels like the Cummins 220. They usually had 5X4 transmissions, and sometimes a manual-shift 2-speed rear end to really give them some gear-splitting ability. 40 forward speeds!
Jerry

That practice continued into the 60's. I bought my first 18 wheeler in March of 1964. We would stand out on the running board not only to get away from the heat, but on a 1st gear hill it wasn't that uncommon for a drive shaft or input shaft to break or an engine to blow up. We knew that we couldn't hold her on the hill and we wanted a head start on jumping clear of the darn thing. Film and photo developing cost money which no one had. And we thought the practice would last forever.

We used to use the throttle on our cattle truck in the field searching for newborn calves. You could set the throttle, get out of the cab & stand on the window opening to get a better view & to grab a hold of the steering wheel if need be. Hadn't thought about that in years!! Try it today & see what happens!!???

Probably not done too much anymore because of safety issues. A friend of mine set his throttle while out in the field and had one of the kids steer while the rest of the kids helped with picking stones. Not long after, one of his kids fell and got run over.

An other use for the throttle knob was for hand cranking the motor to start it with a low battery. The way to do it for a cold start is to set parking brake, put in neutral, full choke, IGN. switch OFF, pump the gas pedal 3 times, insert the crank Handel and turn over the motor about 3 times, leave the Handel at the bottom (close to the road),pump the gas pedal 2 more times and give it some hand throttle, turn ON the IGN. switch, Pull up on the hand crank and the motor should start. NEVER push down on a hand crank because if the motor back fires IT WILL break bones.

Great thread guys, thanks!