How to connect an inoperable automatic choke?
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G3GM :: G3 Tech :: Engine & Driveline
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How to connect an inoperable automatic choke?
by dhw3971 Tue Jul 29, 2014 3:22 pm
After Mr. Backyard Mechanic installed my Q-jet, he did not make the necessary connections to make the choke work. Does anyone have a diagram/instructions on correct plumbing to make the choke functional?
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Re: How to connect an inoperable automatic choke?
by LS_Quest Tue Jul 29, 2014 5:00 pm
It depends on the type of Quadra-flush you have. Can you post a pic of your carb/intake combo?
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Re: How to connect an inoperable automatic choke?
by dhw3971 Tue Jul 29, 2014 5:37 pm
Yes, I'll get a few photos up. Will have to wait until Wednesday. I'm not certain of the particular model of carb OR intake as they were "bargains" from Mr. Backyard Mechanic's Pile of Greasy Leftovers.
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Re: How to connect an inoperable automatic choke?
by pila Tue Jul 29, 2014 9:54 pm
Three types of choke used on those....the divorced choke has a rod going down to a little heat box on the intake manifold next to the carb, which has a climatic spring that opens the choke as it gets hot.
The hot air type has a pipe/tube running from the choke housing, to the exhaust cross-over tunnel under the carb. Not likely that you have this one..
The other one is the electric type...it has a wire spade connection on the choke housing, and is usually wired to the oil pressure switch, so it only heats the choke heater when the engine is running.
Hope you figure it out OK
The hot air type has a pipe/tube running from the choke housing, to the exhaust cross-over tunnel under the carb. Not likely that you have this one..
The other one is the electric type...it has a wire spade connection on the choke housing, and is usually wired to the oil pressure switch, so it only heats the choke heater when the engine is running.
Hope you figure it out OK
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Re: How to connect an inoperable automatic choke?
by 77mali Wed Jul 30, 2014 8:27 am
If your carb is the electric choke type (very common) the only parts that I've found are included in an elect choke kit that includes the fast idle cam and new linkage. You can get these on quadrajetparts.com but it might not be a 100% match to your carb. If you can identify the carb model number (usually an 8 digit number stamped on the carb-see pic) you'll have a much easier time sourcing the correct parts. Just search the numbers online. There quite a few variations of each type of Q-jet that Pila mentioned that seem to be "generation specific". The 60's ones were pretty simple & by the time the 80's rolled around some even came with throttle position sensors, etc.
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Re: How to connect an inoperable automatic choke?
by bigredlaguna Wed Jul 30, 2014 9:25 am
There are also two different types of electric choke. The early type has both hot air and an electric element to assist. The later type is all electric. You can convert most if not all to the full electric version. Just cap off the hot air ports.
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Re: How to connect an inoperable automatic choke?
by pila Wed Jul 30, 2014 1:18 pm
Thanks for that info on the early electric chokes bigredlaguna !
I wasn't aware of those. I have a Q-jet on the bench, that is a hot air type, that I would like to make electric, but haven't pursued info on if it can be done...
I wasn't aware of those. I have a Q-jet on the bench, that is a hot air type, that I would like to make electric, but haven't pursued info on if it can be done...
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Re: How to connect an inoperable automatic choke?
by 77mali Wed Jul 30, 2014 3:57 pm
bigredlaguna wrote:There are also two different types of electric choke. The early type has both hot air and an electric element to assist. The later type is all electric. You can convert most if not all to the full electric version. Just cap off the hot air ports.
James, how the heck have you been?
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Re: How to connect an inoperable automatic choke?
by bigredlaguna Wed Jul 30, 2014 11:19 pm
Just doin' the daily grind these days. Laguna is collecting dust in the garage while I take care of some other things, but I still lurk on here to see what others are doing.
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Re: How to connect an inoperable automatic choke?
by pila Wed Jul 30, 2014 11:22 pm
I see that you are from Garden City. I was there a few times in 1952, while in the military at Ft Riley
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Re: How to connect an inoperable automatic choke?
by bigredlaguna Wed Jul 30, 2014 11:38 pm
pila wrote:Thanks for that info on the early electric chokes bigredlaguna !
I wasn't aware of those. I have a Q-jet on the bench, that is a hot air type, that I would like to make electric, but haven't pursued info on if it can be done...
You're welcome. The conversion isn't a big deal, if the carb already has a spring housing on the side, it can be converted to electric choke by simply capping the hot air ports and using a replacement heater element from any car that used a q-jet w/electric choke. If your carb has the spring divorced from the carb, then look for an 80's carb and use the choke system off of it. The mount points on the carbs should be the same. There are other things like vacuum dashpots that you may have to change or delete, but it will be fairly obvious what you will need when you get into the conversion.
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Re: How to connect an inoperable automatic choke?
by bigredlaguna Wed Jul 30, 2014 11:41 pm
I drive by Ft Riley once in a while when visiting relatives in Manhattan. It's an impressive site to see when they have all the helicopters out on the tarmac.
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Re: How to connect an inoperable automatic choke?
by dhw3971 Thu Jul 31, 2014 3:43 pm
Here is the carb setup I've currently got:
(and I'd really like to get that stud out of the EGR block off plate...the other one came out easy cuz the nut was stuck to the stud)
(and I'd really like to get that stud out of the EGR block off plate...the other one came out easy cuz the nut was stuck to the stud)
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Re: How to connect an inoperable automatic choke?
by 77mali Thu Jul 31, 2014 6:48 pm
It looks like a manual choke to me or maybe hot-air (?) I don't see any tabs for wires on the choke housing. Is there anywhere on that puppy that a choke cable can hook up to? Cant' tell from the photos, maybe I'm missing it?
Anyway, it looks as if the plate on the primaries is stuck open it s/b closed or very close to closed with the engine off and the position of your the fast idle cam is too far forward as a result.
That plate is supposed to close after your done driving. The trick is to adjust the cable and linkage so that when you "open the choke" from inside the car it s/b about the width of a #2 pencil (old school way-lol) to let fresh air into the carb. You can make the opening adjustments slightly smaller or larger if it works better for starting the car.
I'm assuming that inside the choke housing (this is true of electric chokes) there is a thermostat unit with a little tab on it that the fast idle cam linkage slides into, that is there to operate the opening of that "primary plate". If the fast idle cam linkage is not in the tab it will not operate properly. Those little dots on the thermostat housing indicate the settings which to set the choke. Instead of the fast idle cam being as far forward as it is, you should set it & hence the thermostat as close to the 1st dot (facing to the rear of the engine) as possible for proper operation. You may end up having to set it one or two forward- it's kind of trial and error. Hope that helps.
Anyway, it looks as if the plate on the primaries is stuck open it s/b closed or very close to closed with the engine off and the position of your the fast idle cam is too far forward as a result.
That plate is supposed to close after your done driving. The trick is to adjust the cable and linkage so that when you "open the choke" from inside the car it s/b about the width of a #2 pencil (old school way-lol) to let fresh air into the carb. You can make the opening adjustments slightly smaller or larger if it works better for starting the car.
I'm assuming that inside the choke housing (this is true of electric chokes) there is a thermostat unit with a little tab on it that the fast idle cam linkage slides into, that is there to operate the opening of that "primary plate". If the fast idle cam linkage is not in the tab it will not operate properly. Those little dots on the thermostat housing indicate the settings which to set the choke. Instead of the fast idle cam being as far forward as it is, you should set it & hence the thermostat as close to the 1st dot (facing to the rear of the engine) as possible for proper operation. You may end up having to set it one or two forward- it's kind of trial and error. Hope that helps.
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Re: How to connect an inoperable automatic choke?
by bigredlaguna Thu Jul 31, 2014 10:27 pm
That is a hot air choke. The fellow who did this put a vacuum line to it where the hot air is supposed to go. Then he turned the spring far enough to never move the choke blade closed. Just order a replacement electric heater coil from an 80's model carburetor and swap out the spring. It is a direct fit. The vacuum break that is on it already will be sufficient to open the choke slightly once the choke is set correctly.
Wire it to an ignition on source of electricity (not the distributor power wire though, find something else) if you don't want to use an oil pressure switch. Cap the vacuum port and hot air port. There is a calibrated vacuum leak in the hot air choke that the electric choke does not require.
Set the new spring the same way as the old spring. I like to install the cold spring and turn it until the choke blade is closed. If the new spring is marked, you should be able to see an indicator arrow pointing to a range indicator. If not, you can make a reference mark at this point. I like to turn the spring a little tighter once the blade reaches the closed position to ensure adequate choke function. You can adjust from there depending on what your engine needs for good operation.
Done. Miller time.
Wire it to an ignition on source of electricity (not the distributor power wire though, find something else) if you don't want to use an oil pressure switch. Cap the vacuum port and hot air port. There is a calibrated vacuum leak in the hot air choke that the electric choke does not require.
Set the new spring the same way as the old spring. I like to install the cold spring and turn it until the choke blade is closed. If the new spring is marked, you should be able to see an indicator arrow pointing to a range indicator. If not, you can make a reference mark at this point. I like to turn the spring a little tighter once the blade reaches the closed position to ensure adequate choke function. You can adjust from there depending on what your engine needs for good operation.
Done. Miller time.
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Re: How to connect an inoperable automatic choke?
by dhw3971 Tue Aug 12, 2014 9:29 am
OK, thanks for all the help! 
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Re: How to connect an inoperable automatic choke?
by pila Wed Aug 13, 2014 10:57 pm
Great info there on the Q-jet chokes !
Some folks wire the electric choke to the hot wire on the wiper motor, which of course is hot only with ignition on....
Some folks wire the electric choke to the hot wire on the wiper motor, which of course is hot only with ignition on....
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Re: How to connect an inoperable automatic choke?
by pila Sat Aug 16, 2014 6:41 am
I just ordered an electric choke kit from quadrajetparts.com. for the hot air choke conversion. It is under 30 bucks with shipping !
I'll likely get some throttle shaft bushings, and ream the holes in the base on the Bridgeport Mill, so I don't have to buy the reamer kit....
.
I'll likely get some throttle shaft bushings, and ream the holes in the base on the Bridgeport Mill, so I don't have to buy the reamer kit....
.
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