Another question on timing-

[philo_beddoe]

Rochester, qjet, M4ME

And it doesnt make sense to take off before the high idle kicks down, or else the drive shaft will clunk into gear. How did these trucks start in the morning when they were brand new, did the salesman at the dealership sit there and then punch the gas to kick it down when taking someone on a test ride? Or did he clunk it into gear right away while the engine was racing?  Just saying...

[enaberif]

Rochester, qjet, M4ME

And it doesnt make sense to take off before the high idle kicks down, or else the drive shaft will clunk into gear. How did these trucks start in the morning when they were brand new, did the salesman at the dealership sit there and then punch the gas to kick it down when taking someone on a test ride? Or did he clunk it into gear right away while the engine was racing?  Just saying...

If something clunks when shifting into gear you have a worn component somewhere.

[philo_beddoe]

Only if the idle is a little high and only going into reverse, u-joint?

[VileZambonie]

If your choke break working?

[philo_beddoe]

Yes it is, i believe. Here is a crazy question, how are you supposed to start a stock chevy engine? Here is what the manual says, is this right? Why do they tell you to NOT kick down from fast idle?

Will the idle go down automatically, can the choke be adjusted so the fast idle comes down sooner?

My idle wont come down unless i press pedal to floor and back up, contrary to what they say here under the first bullet.

I always forget and disobey the third bullet.

[Greybeard]

Hmmm...

The choke normally cannot pull the choke closed when the spring tension is on it. That is why it says to push slightly to let the pawl out so the choke can close. Pushing the footfeed down all the way does three things, it sets the pawl on the choke in the closed position (butterflies closed), sets the idle speed pawl into the high idle notch, and squirts raw gas into the intake. So, the carb is now set start with the choke blades nearly closed (never want them completely closed unless there is an included air bleed in the butterflies), the throttle blades are slightly opened, and there is raw fuel sitting in the floor of the intake (however, it is injected at a high speed/pressure so it vaporizes some too). This creates a rich fuel to air mixture to help the spark find the fuel better at very low intake air speeds. Too much fuel however and the spark is doused like a match under water.

Once the truck starts it runs at high idle (the high idle setting can be changed on most carbs like the way you did it). The engine should idle at the lowest high idle it can to remain running smoothly when it is cold or about 1200-1400 rpms (YMMV), this should not have to change for different seasons once it is set. (as an aside, I run my distributor power wire through an electric oil pressure switch so the truck will not start until the oil pressure is there, it will also shut down the engine if the oil pump stops working). After the engine has idled at this high speed for a few seconds or longer depending temps (it has to be warm enough on the piston tops to encourage further vaporization of the really cold incoming fuel, in addition, the intake manifold itself has to get warm for the same reason, if an air gap intake is being used with blocked off heat risers, cold starts will always be somewhat troublesome in really cold weather at normal air/fuel ratios), then knock it down to the next setting (if the carb has multiple idle speed settings) or to normal idle with another light push on the foot feed. Sometimes the choke will open and the idle speed will not come down or vice versa, then the carb needs some TLC. The linkage is binding from dirt, poor settings or the choke heater/vacuum lines are not working correctly.

My personal opinion about carbs is that they such simple mechanical devices they defy logic, yet they can cause the most intrepid of intelligent masculine men to go completely crazy trying to diagnose why they don't work right. Besides, a lot of 'carb troubles' aren't after all.   

[enaberif]

If your choke is setup properly yes it will automatically kick down for you.. That is the whole point of the choke.

The choke is a timer and it can open slow or fast depending on weather. If you have it open to slow it will run in high idle for too long and if its too fast it will cause bogs when you try to drive it. Finding the happy medium depending on the truck and weather is the difficult part.

Some people choose to kick it down earlier so they can drive off.

[Greybeard]

If your choke is setup properly yes it will automatically kick down for you.. That is the whole point of the choke.

The choke is a timer and it can open slow or fast depending on weather. If you have it open to slow it will run in high idle for too long and if its too fast it will cause bogs when you try to drive it. Finding the happy medium depending on the truck and weather is the difficult part.

Some people choose to kick it down earlier so they can drive off.

Must be a difference between Holley's and Rochesters. I stand corrected.

I knew Rochesters used vacuum to help release their chokes as well as a heater but never realized it was strong enough to pull it off high idle, guess I never paid much attention.

My Holley Truck Avenger has never self-released even when brand new, neither has any of the square bores I've used over the years. Of course they were all older style carbs using either a heat stove (from the exhaust inside the intake manifold) or an electric heater. Neither was adjustable for any particular weather conditions beyond how cold it is (meaning the colder it was the longer it took for the heat to start working on the bi-metal spring, although the heat -source- [12 volt electric in most modern cases] was constant no matter the temperature).

One thing not touched on is the heat riser proper. The tube from the heat stove around the exhaust manifold going to the stock air cleaner horn (haven't seen one in working condition in decades other than on a show truck). But these work good during warm up in really cold temps. 

[philo_beddoe]

If your choke is setup properly yes it will automatically kick down for you.. That is the whole point of the choke.

The choke is a timer and it can open slow or fast depending on weather. If you have it open to slow it will run in high idle for too long and if its too fast it will cause bogs when you try to drive it. Finding the happy medium depending on the truck and weather is the difficult part.

Some people choose to kick it down earlier so they can drive off.

I would like to operate just like a modern car, and that is...you start the engine, it runs at a slight high idle for up to about a minute and drops down nicely to the normal warm idle.

What do i adjust to get it to kick down easier and faster,,,wothout stomping on the pedal, if the manual says in 30 seconds slightly depress the pedal to kick down the idle.......then how do i do that?!!?  I do appreciate the feedback. Thanks.

Yes, i would like to kick it down earlier, so i can drive off.

[enaberif]

If your choke is setup properly yes it will automatically kick down for you.. That is the whole point of the choke.

The choke is a timer and it can open slow or fast depending on weather. If you have it open to slow it will run in high idle for too long and if its too fast it will cause bogs when you try to drive it. Finding the happy medium depending on the truck and weather is the difficult part.

Some people choose to kick it down earlier so they can drive off.

I would like to operate just like a modern car, and that is...you start the engine, it runs at a slight high idle for up to about a minute and drops down nicely to the normal warm idle.

What do i adjust to get it to kick down easier and faster,,,wothout stomping on the pedal, if the manual says in 30 seconds slightly depress the pedal to kick down the idle.......then how do i do that?!!?  I do appreciate the feedback. Thanks.

Yes, i would like to kick it down earlier, so i can drive off.

Adjust your choke dial. One way will be faster and the other is slower. Nothing carburated will ever function like fuel injection ever.

You technically shouldn't have to kick it down ever as that is what the choke will do for you but some people are impatient.

[Irish_Alley]

i think the main difference between the way how these trucks run now and how they used to is the gas and mixtures we use now. idk what they were back then but it sure is different than now. my 79 would run one way one day and i would fill up and i would have to tune the carb again

[SkinnyG]

I set my choke to be on as little as I can get away with, coming off as quickly as I can get away with, without stalling or choking out.

I never let my vehicles warm up before driving away.  I get it running, and I drive off.  I am just super gentle until the engine warms up.  It will warm up the fastest if it's driving.

I've owned more carbs than fuel injection.  I am ~that~ old.  Or cheap.  Probably both.

[blazer74]

Electric choke on a carb will not kick down by itself.

Will always requires touch of the throttle to disengage the high idle cam from the throttle linkage after the choke spring heats up a bit and allows the high step cam to release.

Adjustments will depend on what your eng wants cold. Choke spring to tight takes to long to come off high idle, too quick and eng stumbles bogs or quits.

I don't wait either much more than less than a minute unless it really cold out. Watch a high idle on icy roads but if weather that bad let it warm up a little anyways if you can.

[VileZambonie]

Electric choke on a carb will not kick down by itself.

T

If it is working correctly the automatic choke should disengage the fast idle once the choke is opened.

[blazer74]

Is there an electric throttle kicker involved?