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my 60 has sat in the garage all week. outside air temps ran from 70-87 degrees. Should my choke and high idle kick in when I start the car with these temps? It doesn't and was wondering if I should adjust the choke spring tension. Thanks!
Don
I have a 62 vette and just had my carb professionally restored and rebuilt.Temps here were in mid 70's to mid 80's and when I start my engine for the first time that day,the choke and fast idle kick in. After a minute, I tap the gas pedal and it goes to idle. Does your choke and fast idle kick in at all in the morning when you start your engine? Try it in the early cool morning after it sat overnight.If it does not kick in, then I think you need adjusting.
Let's assume that "cold" is, say 75 degrees in your garage this time of year. When you "set" the choke before a cold start, the choke butterfly should close fully, even at that "not so cold" temp. When the engine fires, two things happen. First, the choke pulloff opens the butterfly (valve) a small amount to prevent flooding. Next, because it is not exceedingly cold, and the choke spring has weak closing force, and the butterfly shaft is offset (just like the heat riser valve), then the air rushing past the choke valve causes it to open a little bit further. It is this "secondary pulloff" opening which causes the difference in operation between "not so cold" and "ice cold" operation. After this initial "secondary pulloff", the choke valve continues to open on its own as the spring tension continues to decrease.
What this means in NOT SO COLD weather is, that if you set the choke, and leave your foot off the throttle after the engine fires, it should PROBABLY be on the second (not high) step of the fast idle cam, and should stay there. AS SOON AS you tap the throttle, the choke should drop off CONSIDERABLY, because of the "secondary pulloff".
Thanks everyone. I think I will remove the air cleaner before starting at the next cold cycle and observe the choke butterfly position after pressing the peddle to the floor if the butterfly doesn't close I will add more spring tension.
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