VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 winter/summer setting on carb

Anybody change the accel pump setting in the winter and then back in the summer.I understand the long and short stroke for summer and winter.But Im sure most people don't drive much in the winter.Just wondering what setting works the best.

I have never found a carburetor with the pin in either summer or winter holes. It is always in the center or the wear to the arm is in the center hole if the pin is missing. When I rebuild a carburetor I always put the pin in the center hole.

I have never found the pump arm pin in the "summer" or "winter" setting. The pin has always been in the center hole. Same as Dippy Chippy, when I rebuild a customer's carb. I always put the pump setting in the center hole for all purpose driving.

In the center it is, would that be spring or fall

No...the center hole would be more for all purpose driving (average weathter conditions) as stated above.

Now whats the purpose of this setting? Does it have to do with richening the mixture or what?

I think the JYD missed the pun!! Spring and Fall are between Summer and Winter!!

CHEVY SIX 1929-1940 Construction & Restoration by Victor W. Page
Chapter Three page 67
"The cars when shipped from the manufacturing plants, have the pump plunger arm set in its normal position and the change from normal to summer setting should be made when atmospheric temperatures are consistently above 65 degrees F. The change from normal or summer setting to winter setting should be made when the atmospheric temperatures are consistently below 65 degrees F. The center or normal setting will give fair performance, for usual climatic conditions, but if the best performance is desired, the Chevrolet service experts suggest that changes be made according to the above instructions."

With the much better modern gas it can be kept in the center all year long unless you drive in below zero weather.

But what does this do to the carburator? Does it richen the mixture? does it lean the mixture? How does this effect the cars performance?

The longer stroke makes the accelerator pump in the carburetor shoot in more gas when the accelerator pedal is depressed. This would be for the cold weather and to lessen or prevent a hesitation (with a warmed up engine) on acceleration.
In summer the short stroke would squirt in less gas as he engine then requires a leaner mixture for smooth acceleration.
The later Carter W-1's did not have this feature and the oil companies "adjusted" the gas for the seasons. Read like faster burning mixture for the winter for both starting and "running".
Today the mixtures for a given locality change at least four times a year. The faster burning gas also would cause vapor lock in the summer thats why its best not to fill up with winter or fall gas now and use it up next summer.

Intresting. See i've never changed the setting before. I just usually run it mid way. Never had any trouble exept the ocasional spit back if cold.