Original Carter Carb Choke Cam Setting

[Macdon221]

Good Day All,

Original Carter Carb. 440. Original Carter Choke. Spring works fine when heated. Carb is set up meticulously as per the FSM for all settings, Carb works awesome all phases of drive, power and idle. No hesitation or bogs.

When warm...the curb idle screw has been set to the proper rpm (1700) when on the second cam as per FSM. On the first cam it is about 1400 rpm.

My question....

When the car is cold, and the choke rod is pushing the choke closed....should the choke cam rotated by the choke rod so that the fast idle screw is setting on the second cam fully cold, or the third and highest cam? Then when the carb diaphragm energizes on start up and you blip the throttle it takes it immediately pulls it off from a super fast idle to the second cam at 1700rpm?

Hopefully this makes sense!

Thanks

Macdon221

 

[pnora]

Engine off open throttle and close choke with choke rod. Release throttle and look where the cam is. The position of that cam will depend on its rod length. Most likely it will be on its highest setting. What are you trying to accomplish?? The way you make it sound it is working perfect.

 

[Macdon221]

Pnora...Sorry I should of been more clear.

Everything is set up....except the actual choke set up in the manifold well.

Choke Set to the index mark...with the proper skinny spacer....on a summer time cold engine...full accelerator pedal....the choke closes....and the fast idle screw is sitting on the second highest fast idle cam where where you would adjust to 1700 rpm as per the FSM picture. I was wondering if this is correct or if the choke rod indexing should be adjusted to put the fast idle screw up on the highest last cam?

 

[toolmanmike]

Pnora...Sorry I should of been more clear.

Everything is set up....except the actual choke set up in the manifold well.

Choke Set to the index mark...with the proper skinny spacer....on a summer time cold engine...full accelerator pedal....the choke closes....and the fast idle screw is sitting on the second highest fast idle cam where where you would adjust to 1700 rpm as per the FSM picture. I was wondering if this is correct or if the choke rod indexing should be adjusted to put the fast idle screw up on the highest last cam?

It usually doesn't kick down in 2 steps. Depending how it's set (I never use a manual) It usually idles on the highest setting when started cold. I always let it idle for a few min then kick it down to curb idle. If I am starting it in the winter and it's extremely cold, the choke will open more slowly and it might kick down to the middle setting.

 

[pnora]

Pnora...Sorry I should of been more clear.

Everything is set up....except the actual choke set up in the manifold well.

Choke Set to the index mark...with the proper skinny spacer....on a summer time cold engine...full accelerator pedal....the choke closes....and the fast idle screw is sitting on the second highest fast idle cam where where you would adjust to 1700 rpm as per the FSM picture. I was wondering if this is correct or if the choke rod indexing should be adjusted to put the fast idle screw up on the highest last cam?

The choke and rod itself has nothing to do with the fast idle cam and linkage. The actual choke butterfly can only close and open so much. The fast idle cam and rod are set regardless of the choke thermostatic coil itself. You do not adjust a choke spring to dictate the fast idle. The choke needs to fully close and open on its own. You adjust the pull off and fast idle settings as needed. Sometimes the fast idle cams link/rod may have to be bent slightly to make everything work in sync.

 

[R413]

I don't know which step it should go to. I've not noticed it going to the top step. You adjust speed with the screw. It seems nothing on the choke or fast idle goes to the end of the range. Any settings or screw turning, there is always room to adjust both ways.

If you adjust the choke thermostat richer, it will take longer for the choke to come off. You don't want or need that with a new efficient engine. Don't want to over fuel it and wash down the cylinders. How many classic cars do you see that blow black smoke on a cold start? I see too many.

I start out with the choke thrpermostat adjustment in center and us usually don't need to move it from there.

When you pump the gas cold engine it goes on fast idle cam.
When you start the car the choke pull off opens the choke, it will stay on the fast idle cam until you touch the pedal with foot.

 

[AR67GTX]

In the summer my choke on my GTX may or may not even close enough to engage the fast idle cam. It probably does the first step but the stiff engine oil keeps the idle rpm down for a few minutes and then it gradually speeds up a little until warm. But because of my insulated garage, I don’t have my fast idle adjustment set for a high rpm warm up like the manual calls for - maybe 1400rpm after the motor runs a few minutes to move the oil around and warm up a little.

 

[toolmanmike]

In the summer my choke on my GTX may or may not even close enough to engage the fast idle cam. It probably does the first step but the stiff engine oil keeps the idle rpm down for a few minutes and then it gradually speeds up a little until warm. But because of my insulated garage, I don’t have my fast idle adjustment set for a high rpm warm up like the manual calls for - maybe 1400rpm after the motor runs a few minutes to move the oil around and warm up a little.

That sounds perfect to me. I like to set mine a little lean. I can always add more gas or restart it another time. but it's tougher to take gas away when there's too much.

 

[oldbee]

Knock on wood,,, I THINK I adjusted my choke thermostat 1 notch in the year I bought it;’68. Never touched since. Couple carb rebuilds since in 86k miles. Just use all the carb settings like the instructions say in the kit.

 

[pnora]

Knock on wood,,, I THINK I adjusted my choke thermostat 1 notch in the year I bought it;’68. Never touched since. Couple carb rebuilds since in 86k miles. Just use all the carb settings like the instructions say in the kit.

Same here.

 

[Macdon221]

So thought I would do a follow up.

I had 2 original chokes. Dismantled them both. The spring on both of them were the same, or so I thought. One of the springs must have been a replacement spring. The difference was in the angle of the Tang that fits inside the little shaft with the slit in it to act as the center of the rotation. Hence when set to index, they were in different rotational positions causing the choke rod to be in a different height on each when set to index.

I used the original spring, and set it so that the fast idle screw is just sitting on the highest cam with a cold engine. With that setting the index mark is about 1/2 of a mark off factory center setting. Car fires right up each time after cold. On start up the choke diaphragm actuates, and with a little blip of the throttle after start it takes it down to the second highest cam to idle at 1700. A few mins later after it warms a bit I can blip the throttle again and the choke will pull off as the thermostat warms and takes it down to the lowest cam and then finally off.

Works perfect now.

Thanks for all the help.

 

[68BabyBlue]

That sounds perfect to me. I like to set mine a little lean. I can always add more gas or restart it another time. but it's tougher to take gas away when there's too much.

I've got my current GTX set up the same way. My first GTX was set up rich back in the day, to enable starting in PA winters. I often poked the handle of my windshield scraper in the choke plate to clear it after it got too much gas. For sure, it's easier to deal with too little, than too much.

 

[toolmanmike]

So thought I would do a follow up.

I had 2 original chokes. Dismantled them both. The spring on both of them were the same, or so I thought. One of the springs must have been a replacement spring. The difference was in the angle of the Tang that fits inside the little shaft with the slit in it to act as the center of the rotation. Hence when set to index, they were in different rotational positions causing the choke rod to be in a different height on each when set to index.

I used the original spring, and set it so that the fast idle screw is just sitting on the highest cam with a cold engine. With that setting the index mark is about 1/2 of a mark off factory center setting. Car fires right up each time after cold. On start up the choke diaphragm actuates, and with a little blip of the throttle after start it takes it down to the second highest cam to idle at 1700. A few mins later after it warms a bit I can blip the throttle again and the choke will pull off as the thermostat warms and takes it down to the lowest cam and then finally off.

Works perfect now.

Thanks for all the help.

Excellent.

 

[Dragon Slayer]

The well choke is set to hold choke valve closed until engine warms up and open the choke valve. More tension on choke valve longer to open and run richer. Less tension opens faster. Normally you leave factory units alone.

The Diaphragm is a choke pull off. Since choke is closed to start. Once engine starts and generates vacuum the pull off opens choke blade slightly against tension of choke to let more air in and prevent over rich running condition. SVM has spec for blade opening.

As stated the fast idle is a separate setting usually on second highest notch. Adjusted on car running to dial in the rpm. Once choke fully opens the choke shaft cam/rod puts pressure on the cam and when you blip throttle and fast idle screw moves away from notch, the cam is released and moves so that throttle can move more closed to lower idle position and the fast idle screw no longer touches cam.

So any adjustment to the well choke is to set how quickly the choke goes fully open. Mild winters you may use less tension, colder more. Or depending on how fast you decide to drive away after starting. If blade goes open too soon in cold weather you may stall if driving.