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Old 12-07-2020, 01:20 PM
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Default Integral e-choke/q-jet question

The one issue that I have and do not like with the e-choke/q-jet (with integral choke) combo is that in the type of weather we're experiencing right now...Averaging just about 40~50 degrees or so in the daytime... The choke coil cools down much quicker than the engine and when I start the car after being shut down just a few minutes, the high idle kicks in even though the engine is still fully warmed.
By the time I get out of the parking lot, I can bump it down but it's a hassle switching to neutral as I'm driving and bumping the pedal and I know it's not supposed to be that way.
Am I missing something about how to set this up?

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Old 12-07-2020, 01:34 PM
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I am no expert but I kinda wish I'd gone with a manual choke for my truck. The electric choke just seems to be hard to get right.

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Old 12-07-2020, 01:45 PM
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You could try to tweak choke adjustment a little leaner(clockwise). That will shorten the time the choke is 'on' and may help when it get cooler out. You may be on the edge of having it 'on' too long when full cold.

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Old 12-07-2020, 02:30 PM
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you should be able to blip the throttle to get it to kick off of high idle:
Is something askew that prevents you from doing this?

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Old 12-07-2020, 03:59 PM
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i agree turning the choke dial counterclockwise a little will pull it off a bit faster & not engage it as soon after shut off. another thing i found when you find the sweet spot for the dial, is to back off the fast idle adjuster screw a bit, if its set to high then it engages the steps on the cam more. some of the factory high idle rpm specs are a little too high IMO & when the weather changes it can make the choke stay on longer or at higher rpms than needed.

im in iowa & deal with this on my e-choke & manual choke cars every season, but have got the dial & flap adjustment in a pretty good spot, backing off the high idle screw about 1/2-1 full turn seems to fix the issue you describe. but im no carb expert, just saying what works for me.

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Old 12-07-2020, 03:59 PM
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Quote:
Originally Posted by unruhjonny View Post
you should be able to blip the throttle to get it to kick off of high idle:
Is something askew that prevents you from doing this?
Yes, why is it an issue? You can blip the throttle with little effort to get off fast idle. There is an internal vacuum break inside the choke housing that will pull the choke open partially at startup. This, in combination with setting the choke slightly leaner will take care of your problem.

The original choke would act no differently than the electric. The choke housing cools down faster than the engine.

Maybe you need to convert to FI?

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Old 12-07-2020, 05:34 PM
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Quote:
Originally Posted by Dick Boneske View Post

The original choke would act no differently than the electric. The choke housing cools down faster than the engine.

Maybe you need to convert to FI?
I know that the housing cools down faster than the cast engine but not in the time it takes to pump 10 gallons of gas. As I said in my original post, I can bump it down.
I'll figure it out.. Make some adjustments. It's not a big deal.

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Old 12-07-2020, 05:36 PM
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Obvious, but make sure itís not getting a little gummed up also. Seems like every few years I have to spray my linkage as it gets a little gummy and hangs up a little.

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Old 12-07-2020, 08:08 PM
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I agree with Greg. Only time it bothers me is leaving a car show or gathering where there is a audience at startup, and despite a lot of fine tuning the choke still cools off enough that it "thinks" a little fast idle is needed. This only seems to happen on my electric choke Quadrajet, and a little less adjustment hurts the initial actual cold start. My band-aid approach is to simply turn the key on and sit there with the choke coil heating up beforehand. Only takes 30 seconds to avoid the embarrassing fast idle start.

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Old 12-07-2020, 08:37 PM
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Yeah, I like that idea Mick. I'm glad you chimed in. From reading the previous responses I was beginning to think that I was the only one who ever had that issue. Now I won't have to go to fuel injection.
I did a full rebuild using Cliff's recipe just a few miles ago. Runs great and clean enough to eat off of so nothing's sticking.

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Old 12-07-2020, 08:57 PM
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That’s exactly what we do on our kid’s Plymouth. Switched to e-choke when we swapped out his manifold. I wasn’t fond at first, but after learning you could give it your own “input” with a key turn and how long you choose to wait, it’s actually convenient.

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Old 12-07-2020, 09:29 PM
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As Dick B has said, the vacuum brake can also be adjusted to minimize the time it is on high idle, many times the only adjustment people make is to turn the choke thermostat to try and solve their choke problems. Making sure the vacuum brake is opening the choke butterfly up upon fire up, and the high idle specs are correct, and within the specifications makes a lot of difference in how an combination acts when it's cold.

Having all three adjustments correct is when the carb will act nearly as well as a FI setup does. No excessive fast idle, and no flat spots or coughing through the carb when trying to accelerate when cold. And no overly rich exhaust from the tailpipes, the kind that makes your eyes burn.

It's also important to observe how fast the vacuum brake opens the choke upon startup. A small hole in the diaphragm will make it pull lazily and not open the choke as quickly as it should open, nor as far as it should open. It's best to use a vacuum pump to set the vacuum brake to specifications, and test it's operation. taking the time to set all three adjustments usually will have a much greater effect than just turning the choke thermostat.

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Old 12-08-2020, 01:50 AM
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The electric choke mechanism has less mass--and therefore cools down faster than a system that depends on intake manifold temperature such as a divorced-choke coil, or even a hot-air choke.

Even so, you should be able to kick from the highest step of the fast-idle cam to the second-highest step INSTANTLY upon starting the engine; and the second-highest step shouldn't have the idle speed so fast as to cause any sort of discomfort. My guess is that you don't have the choke pulloff/vacuum break, the choke-blade position, and the fast idle cam position properly synchronized. With the choke COIL still trying to close the choke, the pulloff/vacuum break should pop the choke blade open far enough that the engine doesn't gargle on gasoline, and with the choke blade forced open by the pulloff/vacuum break--the fast idle cam should rotate to the second-highest step as soon as you touch the gas pedal enough to release pressure on the fast-idle cam. Point being, it's a three-way relationship between pulloff/choke blade/fast idle cam; with the choke coil position and the fast idle screw adjustment making things just a little more complex.

https://www.chevelles.com/threads/ad...roach.1131913/

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Old 12-08-2020, 09:57 AM
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The average backyard mechanic usually only adjusts the choke thermostat when they have a problem with the cold running. What Dick B, Shurkey, and myself have tried to convey is that the relationship between all 3 adjustments (vacuum break/choke pulloff, fast idle, and choke thermostat tension) is imperative to proper operation in cold weather.

If the specifications for your particular carb don't work with an electric choke substituted for a heated thermostat, you might have to try substituting the specs from the Q Jet that the electric choke came on from the factory, but I would try the specs from your carb first.

The article that Shurkey refers to on the chevelle site is what adjustments you need to make in addition the the choke thermostat tension to have proper operation of a Q jet, or any carb when it's cold. Cliff Ruggles also commonly refers to a properly set up O Jet having mostly the same manners as FI during warm up, and properly adjusted, this is true.

If you have a fairly lumpy camshaft it may not have enough vacuum at idle to pull the vacuum break/choke pull off to activate it properly. You would need to put a vacuum gauge on the engine to determine how much vacuum it has and if the reading on a pump such as a mityvac unit would have enough vacuum to operate the unit as required. Although the partially closed choke during warm up should raise the reading to an acceptable level, I would think that you'd have to have a really radical camshaft to lose enough to make the vacuum too low.

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Old 12-08-2020, 10:32 AM
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The pulloff is adjusted and I believe it's correctly adjusted. There are no leaks in the diaphragm. The carb runs very, very well. No coughing, no flat spots, great idle. The ONLY issue I have is the one I've described. I'm pretty meticulous with that kind of stuff and even fabricated a reducer to go in the diaphragm line to adjust the pull-off dropout time. I set the gap in the choke valve using a drill bit...can't remember what the specs were now but it was set.
The engine starts cold with high idle just like I want it to, just drops out a little quick when the engine is cold and comes in a little quick when the engine is warm. This is really the essence of my issue.
I can look at all of those adjustments again as I think it was summer when I originally set it up. I remember leaning the choke spring just a tad when I first finished everything because I did not like the bit of black smoke when the choke was fully cold. Leaned it out just a bit and got rid of that but now the choke will lean out just a tad colder than I would prefer.
Maybe the cold weather requires me to take few minutes to check everything over again...?
Again, none of it is a major issue. I rarely drive it in cold weather but I did this past weekend. Otherwise, I may have never noticed it going back to hi idle after being shut down probably 3 minutes tops.
It's a 1974 carb by the way and also, just as a point of interest, I have rebuilt 4 of these carbs using Cliff's recipe and quite a few others before I knew to do anything other than disassemble, clean and reassemble so it's not like my very first rodeo on this.
I'll take a look at the chevelle site and see if there's anything there that opens my eyes to something I completely did not know about in that dept.

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Old 12-08-2020, 11:33 AM
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Greg, as Shurkey has referred to the mass of cast parts of the hot air chokes keep the choke from re-applying as quickly as the electric ones do. You might need to find out what carb the electric thermostat comes on, and use those specs instead of the OEM 74 specs.

The quick cooling off of the electric chokes is why I usually try to use the engine heated chokes on my own cars. I do however remember working on a few of the electric chokes in the dealerships where I worked in the mid 80s and those cars didn't seem to have the common problems associated with electric chokes when doing a conversion from engine heated to electric. That might be attributed to different specs for the choke pull offs, and high idle specs.

The magnetic choke angle level gauge (pictured in the chevelle article) was used on most of the later carbs, instead of the drill gauges to set pulloff opening. That could be a problem when converting to the newer specs if you decide this might be the key to your problem. Most people that don't work on carbs for a living wouldn't have that tool at their disposal. I happen to own a Kent Moore carb gauge set of tools, but the average Joe isn't going to have the set. I'm sure you could buy the magnetic choke angle gauge separate though if you googled it. GM/Rochester decided that the choke angle gauge was more accurate than just using drill gauges during the closing years of carburetors.

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Old 12-08-2020, 11:42 AM
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Here's a Thexton one that is shipped from GA, same state, for $22:

http://www.2040-parts.com/gm-choke-a...-nos-i1888576/

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Old 12-08-2020, 11:57 AM
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Quote:
Originally Posted by Sirrotica View Post

The quick cooling off of the electric chokes is why I usually try to use the engine heated chokes on my own cars. I do however remember working on a few of the electric chokes in the dealerships where I worked in the mid 80s and those cars didn't seem to have the common problems associated with electric chokes when doing a conversion from engine heated to electric. That might be attributed to different specs for the choke pull offs, and high idle specs.

The magnetic choke angle level gauge (pictured in the chevelle article) was used on most of the later carbs, instead of the drill gauges to set pulloff opening. That could be a problem when converting to the newer specs if you decide this might be the key to your problem. Most people that don't work on carbs for a living wouldn't have that tool at their disposal. I happen to own a Kent Moore carb gauge set of tools, but the average Joe isn't going to have the set. I'm sure you could buy the magnetic choke angle gauge separate though if you googled it. GM/Rochester decided that the choke angle gauge was more accurate than just using drill gauges during the closing years of carburetors.
Thanks Brad for the information and the link. I've never seen any angles listed for pulloff settings on the carbs I've fiddled with, or at least I don't recall seeing them, not sure if I could apply that to this carb.
I have wondered if I just got an off brand e-choke that maybe is a little too sensitive to temp changes. That might explain why it actually heats up faster AND cools down faster than I would like. I cannot for the life of me remember where I got this one. In the past, I have used a NAPA part and I don't recall having this issue back then.

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Old 12-08-2020, 12:30 PM
Baron Von Zeppelin Baron Von Zeppelin is offline
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Pull cable / manual chokes have always been my favorite.
With the repo underdash Ram Air cable brackets for 69-70 available, one of those could be used for a choke cable mounting - and have a built-in cool factor.


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Old 12-08-2020, 01:20 PM
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Quote:
Originally Posted by Greg Reid View Post
I remember leaning the choke spring just a tad when I first finished everything because I did not like the bit of black smoke when the choke was fully cold. Leaned it out just a bit and got rid of that but now the choke will lean out just a tad colder than I would prefer.
CLASSIC symptoms of not having the pulloff open the choke blade far enough--and then adjusting the choke coil instead of the choke pulloff.

Downside is that it may make the choke-coming-on-when-the-engine-is-still-warm problem worse.

I'd try it and see--tighten the choke coil back where it was, adjust the pulloff to pop the choke blade open a hint more. (It won't take much!) Verify fast idle cam is on the second step when the pulloff is opening the choke, and verify fast idle speed

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