The Stovebolt Site Forums The Shop Area Engine Shop Why a manual choke

I have restored the Zenith single barrel carburetor on my 58 Jimmy Series 100 stepside pickup. Now, this came with - and the replacement I put in the truck has - a manual choke.

I found that these were also put on late forties / early fifties Chevy passenger cars, but by 54 cars were coming with automatic chokes. My 54 sedan has one. So why would a truck built four years later come standard with a manual choke?

Toying with the choke at stop lights and on the highway, I can certainly feel the effects of opening and closing the choke at idle and at 65 mph.

But why not an automatic choke on a pickup?

What are some hints on how to apply the choke for maximum fuel efficiency?

wen you go to start your truck pull it most of the way out once it is running push most of the way in and then once you hit the road and engine is warm push all the way in DO NOT PULL IT OUT WILE DRIVING AND EGINE IS WARM it will only be hard on your engine and make it get worse milage
wen the truck is warm you do not evan need it to start
judging from your post I think you would be better off with a automatic choke

Hey oldchevy46!

I think what I would like to know is a bit of history, I think (I'm anal about history - I love it and live it!).

What do you think GM was thinking when they put manual chokes in vehicles? Was it maybe just the technology of the times? Limitations of engineering? And why would trucks lag cars in applying automatic chokes?

This truck is a bull. I commute at least three days a week with it over 100 miles round trip with never a failure of any kind. "Animal" is a reliable and strong truck.

earliest technology was manual for everything - I'd think the difference shifting to automatic is simply that the cars were getting aimed more at "suburban housewives", while the trucks were still aimed at farmers and tradesmen who knew machinery and didn't wanna spend more than necessary - hand choke goes right along w/ hand throttle, which also disappeared on cars way B4 trucks - main thing is cheaper prolly, but GM also tended to use up stock on hand on the trucks - auto chokes on trucks started happening w/ the V8, and the trucks started being marketed to "surburban cowboys" ie: Cameo design

Bill

Manual chokes were used on Chevy pickups with manual transmissions at least as recent as 1970 (perhaps a few years later). Medium duties still had them in 1975. Although a properly adjusted automatic works pretty well, I prefer a manual choke. It's more dependable and, once you get used to your engine's personality, will get you going faster in cold weather. Every engine seems to be unique; I have owned dozens of vehicles with manual chokes and no two started exactly the same. The same procedure that would lean-stall one engine would flood out the next. Even if you hate modern complications, you gotta' appreciate EFI for easy starting!

I have owned and worn out 8 new vehicles over the past 30 years. Before EFI, automatic chokes worked great for the first couple of years and then they were a pain in the neck. This is considering wintertime temperatures of down to about -30 Deg. F. They could never be made to work like new because of many factors. I think that cars were for the pampered majority and trucks were just plain rugged machinery,(much better thatn cars!). I would have traded a manual choke for the automatic choke anytime. Also, they probably required the most predictable controlled performance for motors with automatic transmissions and they were more common in cars.

My old man tells the story of how the lady got bad gas mileage because she used the choke handle for a purse hanger

They started making automatic chokes because people don't understand automotive basics. Women especially didn't want to fool with a choke. They are not as maintainance free as a manual choke however and eventually break. Auto chokes on later model carbs with all the emissons crap became very very complex.

I love the manual choke on my 62, 3/4 PU.

I sure do appreciate the feedback on this question. I think what was said about the pampered masses is probably nuts on. Too, as a production engineer, I understand the comment about GM draining the inventory to the bottom before expending design time on newfangled changes.

Too, the comment about the automatic chokes becoming a pain in the a-- with age has been true for me since my first car in 78.

Hey Dukw45! You're right about getting to know the engine. The manual choke has helped me learn about this 270 CID engine pretty well - how he likes the cold and how he runs in the Carolina summer heat.

HAPPY NEW YEAR y'all!

My retrofit manual choke on my '65 Impala 283 was also an anti-theft device. If you didn't use it, you could not drive it off.

I just like the "What's that thing for" question. My wife asked that when I was showing her the truck the first time. (kinda sounds like the punchline to bad off-color joke, doesn't it? )