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Re: 1973 340 Choke Thermostat [Re: 440newport] #966093
04/06/11 06:12 PM
04/06/11 06:12 PM
Joined: Oct 2008
Posts: 765
Shoreline, Washington
72roadrunnergtx Offline
super stock
72roadrunnergtx  Offline
super stock

Joined: Oct 2008
Posts: 765
Shoreline, Washington
Quote:


You can get a modern equivalent that works the same, but they don't look like originals.



I would question referring to any of these variants as a "modern" equivalent. There was a later 70s design (button style),replacements are still in production in the aftermarket world.
If you chose to go with the NOS versions of the original design, be sure to get a couple of spares, they didn't last long back then and won't last any longer now. The high current draw of the heating element burns the contacts to the point that current no longer passes through it at all. Careful describing the resistor as a ballast, it's simply a power resistor used originally to give some versions of the controller two levels/stages of power/voltage to the heater. The later button style controller had some versions having the power resistor connected as a by-pass. The contacts were either closed (providing full voltage to the heater) or when open, depending on engine temperature, would provide partial voltage, via the power resistor, throughout the remainder of the run cycle.
Reminder, current aftermarket electric chokes don't pull anywhere near the amount of current these OEM heaters do and are designed to be connected to ign-run circuits full time. Any currently available aftermarket choke delay/timer controls will not likely handle the current load of the factory type heating elements for very long.

Quote:

Lets say the crossover is blocked off such as with the Edelbrock heads. After the car warms up, do you constantly power the choke thermostat to keep it open? Or will the thermostat burn up?




If your cross-over is blocked, like I found with the Edlebrock heads/six-pack set-up, you may need to run a by-pass design as I have described in the above link. I wouldn't run the full current of that heater though my wiring full time. Heating element is not likely to burn-up, the wiring, bulkhead connectors, ignition switch and it's connections likely will.


1972 Road Runner GTX 440 6bbl 5-speed
[img]http://72rrgtx.com/carpics/bucket/DSC06730r-1.jpg[/img]
Re: 1973 340 Choke Thermostat [Re: 72roadrunnergtx] #966094
04/06/11 06:58 PM
04/06/11 06:58 PM
Joined: Aug 2007
Posts: 6,089
Valencia, España
NachoRT74 Offline
master
NachoRT74  Offline
master

Joined: Aug 2007
Posts: 6,089
Valencia, España
Quote:


If you chose to go with the NOS versions of the original design, be sure to get a couple of spares, they didn't last long back then and won't last any longer now.




well actually I have in my car one still working since factory days, from a donor 400 engine I got around 10 years ago.

and haven't found it gets me high loads to the system

maybe just luck ?



With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: 1973 340 Choke Thermostat [Re: NachoRT74] #966095
04/07/11 12:18 AM
04/07/11 12:18 AM
Joined: Oct 2008
Posts: 765
Shoreline, Washington
72roadrunnergtx Offline
super stock
72roadrunnergtx  Offline
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Joined: Oct 2008
Posts: 765
Shoreline, Washington
Are you sure it's still fully functional? Taken any measurements lately? resistance across those contacts when cold? Full battery voltage at the heater when controller is activated? Had it open to have look inside? I've personally replaced hundreds of those controllers (including the later button type) wrenching on these cars back in the day at dealers. So common for them to have stop functioning in short order, they were considered a tune-up part, automatically issued out over the back counter along with the spark plugs, PCV valves, and filters on almost every car. Why do think there are so many NOS controllers for sale today? Factory tune was so lean, most cars had better cold drivability without the choke spring heater functioning. Most cases, mileage suffered somewhat with the prolonged choke function which tended to help bring the vehicles in for the tune-up in the first place. I have two NOS controllers right now, one lasted about 6-months before I designed something that could handle the heating element current and didn't depend on a small bi-metal strip for its timing.


1972 Road Runner GTX 440 6bbl 5-speed
[img]http://72rrgtx.com/carpics/bucket/DSC06730r-1.jpg[/img]
Re: 1973 340 Choke Thermostat [Re: 72roadrunnergtx] #966096
04/07/11 12:28 AM
04/07/11 12:28 AM
Joined: Aug 2007
Posts: 6,089
Valencia, España
NachoRT74 Offline
master
NachoRT74  Offline
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Joined: Aug 2007
Posts: 6,089
Valencia, España
well last time I checked was functional... but it was long time ago...

will check soon


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: 1973 340 Choke Thermostat [Re: NachoRT74] #966097
04/12/11 11:23 PM
04/12/11 11:23 PM
Joined: Jan 2003
Posts: 1,547
Puyallup, Wa.
S
Steve340 Offline
pro stock
Steve340  Offline
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S

Joined: Jan 2003
Posts: 1,547
Puyallup, Wa.
This is the 340 one. Part # 4027793.

6582509-73choke.jpg (327 downloads)
Last edited by Steve340; 04/12/11 11:25 PM.
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