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bimetal coil in automatic choke mechanisms
https://www.slantsix.org/forum/viewtopic.php?t=18710		 Page 1 of 1
Author:  Wizard [ Fri Jul 21, 2006 5:11 pm ]
Post subject:  bimetal coil in automatic choke mechanisms
Now I have new appreciation of people who had to tinker, tinker and TINKERED choke action endlessly on those and especially the 5220 carbs.

:D

This is on mopar 2.2L with 5220 carb. All I wanted is your greatest expertise on carb choke stuff.

Ok, 2 years ago I had choke bimetal coil set correctly to close on it's own lightly when cold and was still is last year. Not right now this time. Seems the bimetal coil went stretched and now won't close on it's own when cold, even I pushed choke mechanism closed and let go, sprung partially open. Rendering cold starts impractical. So this made me think that one is junk and have to get another coil.

Think so?

By the way, I'd love to find a source for BRAND NEW choke heater with bimetal coil assembly. All I do is just swap it in and adjust.

Cheers, Wizard
Author:  SlantSixDan [ Fri Jul 21, 2006 5:34 pm ]
Post subject: 
Ask and receive!
Author:  Wizard [ Fri Jul 21, 2006 6:31 pm ]
Post subject:  Thanks!
I was looking for your experiences with choke thermostats do they go stretched prematurely on their own (lost springiness).

So that makes me wonder if reusing useable choke thermostat carries some risk that it will fail soon in same manner. Thermal heater is not the point, btw. :)

Fired off few questions and a request for the choke thermostat to carbsonly.com.

Cheers, Wizard
Author:  RossKinder [ Fri Jul 21, 2006 7:38 pm ]
Post subject:  Re: Thanks!
Quote:
I was looking for your experiences with choke thermostats do they go stretched prematurely on their own (lost springiness).

So that makes me wonder if reusing useable choke thermostat carries some risk that it will fail soon in same manner. Thermal heater is not the point, btw. :)

Cheers, Wizard
I've never had a bimetal stay perfectly adjusted over a long time. Every one I've ever had required re-adjustment from time to time. Is that unalterably normal? Can't say. Do they make really bad ones now and then - or all the time? Can't say.
Author:  SlantSixDan [ Fri Jul 21, 2006 7:57 pm ]
Post subject:  Re: Thanks!
Quote:
I was looking for your experiences with choke thermostats do they go stretched prematurely on their own (lost springiness).
Yep, after many years and many thermal cycles, the bimetallic's behaviour can change. One or both of the metals can become annealed or work-hardened or crystallised. The two metals can come unbonded from one another. Corrosion can affect it. Or, it can just plain get old.

A bimetallic in good and untweaked condition will hold an adjustment for long periods of time (many years). If you find yourself unable to obtain a workable choke adjustment and everything else in the system is in good shape, or if you find yourself having to make constant adjustments, a new bimetallic is likely indicated.
Author:  Wizard [ Fri Jul 21, 2006 8:24 pm ]
Post subject: 
Great!

That kind of talk I like to see, that confirms my thoughts that old bimetal is "wearing out" on mine.

So time for another one swapped in from my little pile of 3 other carbs for time being till I manage to get new one.

Cheers, Wizard
Author:  john grady [ Mon Jul 24, 2006 2:44 pm ]
Post subject: 
a stuck heat riser will cook em....more likely? At least on V8's. Chrysler 300 club Int. resells tham and shetetmetal pot under them, on ram cars
Author:  SlantSixDan [ Mon Jul 24, 2006 2:57 pm ]
Post subject: 
Quote:
a stuck heat riser will cook em....more likely? At least on V8's.
Not on slant-6s.
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