Thermoquad choke question

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halfafish

halfafish

Damn those rabbits, and their holes!
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I'm doing a conversion on my 72 Coronet 318 from a 2-bbl BBD to a 4-bbl. I have a factory 72 340 Thermoquad intake and a 72 6139S Thermoquad carb to rebuild. The intake has nothing for the choke mechanism, and I didn't get one with the carb. Does someone have a photo of what this should look like? I'm nobody's idea of a perfectionist or numbers-matching guy so I'm not after NOS parts. I see some stuff on eBay that's supposed to be correct but I'm hesitant to order one without knowing it's the right critter for the job.

TIA!
 
I'm not sure what the stove is? I'm missing the bimetal coiled thing with the arm on it that bolts to the intake and goes to the carb, as well as the little cover that goes over it all. Or at least that's what I think I'm missing. Haha. Hard to figure out what's not there, if it's not there...
 
This type of choke well should be what you have-
1704591236426.png

On this type, the choke well is open to the exhaust crossover. As such, it needs a "bathtub" which sits in the well, and a gasket to go between them, like this:
1704591852757.png

This seals the crossover and prevents exhaust leaks.
You can most likely use the one from your 318 manifold, or else some kits have them included.
1704591996589.png

72 340 THERMOQUAD CHOKE STAT, AND CUP. | eBay
Then the choke thermostat gets installed on top of the tub.

Bucks down? Use your 318 BBD choke. Bolt it up to the 340 manifold, and set the TQ and it's spacer gasket (you absolutely need the thick isolator gasket, just like the factory used) on the manifold, and make sure the carb's choke is closed. Now attempt to line up the thermostat's choke rod with the choke arm on the carburetor- you'll probably find the rod is about two inches too short. Now get creative- look at the coil spring, and you'll see that it can be separated from the rod fairly easily with a little finagling. Now get a piece of rod, coat hanger, whatever- and start bending. Mimic the ends of the old rod, adjust the length measurement to fit making sure it will not interfere with any carb linkages or fittings. Reinstall your new rod on the spring, and hook up to the carb, making sure it has free range of motion.
It will now operate as intended- the thermostatic coil doesn't care if it is operating a 2 or 4 barrel, only the rod differs.
 
Professor Fate said:
This type of choke well should be what you have-
View attachment 1716188810
On this type, the choke well is open to the exhaust crossover. As such, it needs a "bathtub" which sits in the well, and a gasket to go between them, like this:
View attachment 1716188819
This seals the crossover and prevents exhaust leaks.
You can most likely use the one from your 318 manifold, or else some kits have them included.
View attachment 1716188820
72 340 THERMOQUAD CHOKE STAT, AND CUP. | eBay
Then the choke thermostat gets installed on top of the tub.

Bucks down? Use your 318 BBD choke. Bolt it up to the 340 manifold, and set the TQ and it's spacer gasket (you absolutely need the thick isolator gasket, just like the factory used) on the manifold, and make sure the carb's choke is closed. Now attempt to line up the thermostat's choke rod with the choke arm on the carburetor- you'll probably find the rod is about two inches too short. Now get creative- look at the coil spring, and you'll see that it can be separated from the rod fairly easily with a little finagling. Now get a piece of rod, coat hanger, whatever- and start bending. Mimic the ends of the old rod, adjust the length measurement to fit making sure it will not interfere with any carb linkages or fittings. Reinstall your new rod on the spring, and hook up to the carb, making sure it has free range of motion.
It will now operate as intended- the thermostatic coil doesn't care if it is operating a 2 or 4 barrel, only the rod differs.
Click to expand...
Aha! Thanks, I will check out the current choke. I still have to remove a broken stud on one of the choke bolt holes, and if that's not enough fun someone already tried to get it out. There's a drill bit or easy-out in there too. Funfunfun! I'll be doing a different thread when I get closer to starting this project, I still need to figure out a cam and finish gathering the other parts.
 
halfafish said:
Aha! Thanks, I will check out the current choke. I still have to remove a broken stud on one of the choke bolt holes, and if that's not enough fun someone already tried to get it out. There's a drill bit or easy-out in there too. Funfunfun! I'll be doing a different thread when I get closer to starting this project, I still need to figure out a cam and finish gathering the other parts.
Click to expand...
Ugh- I feel for you. That can be a real Be-otch. If you've got an O/A torch, try heating up the snapped bolt/drill/EZ out cherry red (but don't melt it), then let it slowly cool- it can take some of the temper out of the steel and make it easier to drill out.
 
Take the intake to a machinist and have him cut the bolt. Some places have a machine like and edm specifically for zapping broken bolts and taps out.
 
Broken bolt in choke stove. You can make a bracket that bolts under the carb mounting bolt to hold the plate in place. No need to drill anything out.
 
Hey man!!!
see post #7! you need that sheet metal cup that fits down in the housing to seal off the exhaust gas passing under the carb. The bimetallic coil (with the housing over) then goes on top of that. By the way, if you use the gaskets that block the exhaust from running under the carb it will take FOREVER for the choke to open!
 
Yeah if you choose not heat the manifold you will need electric choke or none at all (bad idea). I would get standard gaskets, but that's really up to you.
 
Oldmanmopar said:
He will still need the well to seal the intake.
Click to expand...
I did not like the way the choke sat on the well, so I eliminated the well and made a small aluminum cover to seal the exhaust port using the original well gasket. Mounted the choke bracket on top of the plate......Looks awesome
 
Professor Fate said:
Ugh- I feel for you. That can be a real Be-otch. If you've got an O/A torch, try heating up the snapped bolt/drill/EZ out cherry red (but don't melt it), then let it slowly cool- it can take some of the temper out of the steel and make it easier to drill out.
Click to expand...

I was going to try this next, getting the manifold hotter than the bolt, and put some Kroil on it while it's hot. I'll do this several times and see if I can tap it out. I have a little nubbin or two to work with so we'll see what happens. If this is a no-go I'll either go the EDM route or add the bracket at the carb bolt as described above.

As always, thanks for all the info so far.
 
No, you want the broken bolt hotter than the intake....not the other way round. Get the bolt red hot, it goes soft...& contracts. Once cooled down, the bolt will be looser.
 
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