Hello folks,

I have always been a hand choke kind of person which leads me to wonder: Why doesn't the bimetal spring in elec. choke not burn out?

Seems to me that since it is wired in to the "hot" when running side of an ignition switch, the choke bimetal coil would just keep heating. I can't imagine a bean counter putting in a thermal feedback loop in the coil to regulate temp to a certain amount and no more, unless the "bimetal" somehow performs a temp monitor function.

Obviously someone figured it out, else there would be a lot of melted and shorted choke coil springs, but I am not in that select group!

rock]
'64d100

The bimetal itself isn't hooked up to electricity. There's a small ring-shaped heating element (toaster/oven/stove "calrod" type) right next to the bimetallic coil, and that heating element is hooked up to the choke modulator, which does indeed apply or withhold power to the choke heater depending on ambient temperature and other factors. Hooking up the choke heater to ignition-on 12v makes operational problems (choke comes off too quickly whether or not the engine has started). The heating elements are pretty durable; they don't tend to burn out.

A well-set-up manual choke works well; a bodged conversion is a nuisance. The electric choke kits tend to work better than most of the factory setups.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan,

Many thanks! I see now, 3/4 or so, but in contrast to the kit does a stock electric choke (such as that on an Edlebrock or Holley) mechanism have the modulator (calrod, stove, etc) INSIDE the black housing on the carb?

I like the kit very much because it seems infinitely adjustable, whereas electric choke housings I have played with are not. I have never taken the black round housing off an electric choke because, I never had one but also if I did have one, I would be concerned the spring would fly out and uncoil for ever.

Sounds like this is not the case from your reply. Instead it seems the two electric connectors on a stock housing (the ones that look like the ones in the kit example) go, one to ground and one to a heater inside the housing, whereas in the kit example the tabs go to ground and to the EXTERNAL heater.

Is that the deal? If so I am gonna get a junker and open it up to study a tad.

Thanks!!
rock
'64d100

I'm not sure what Edelbrock and Holley, etc., are offering in the way of choke modulators. It's difficult but not impossible to imagine their integration into the choke housing; generally the best location for the modulator/temp sensor is atop the cylinder head to sense actual engine temperature. The integral electric chokes you mention have similar construction to what I described (heating element next to bimetallic coil). Most of these can be adjusted by loosening their retainer screws and rotating the housing in the direction the choke plate closes for more choke action, against choke plate closing for less choke action. You needn't worry about the spring flying apart; it's firmly anchored to the housing and has an open-hook end for easy disassembly and reassembly.

Not sure I understand your comment about stock housings vs. kits; they're basically identical: A feed terminal and a ground terminal, passing through the housing to supply power and ground to a heating element located next to the bimetallic coil.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Choke springs do age and sometimes change characteristics dramatically (opening way too fast); I suspect this is due to cracks forming, although they weren't easily visible to the naked eye. The factory electric chokes of the black cylinder design often have a piston under them that pulls the choke open by vacuum; all the stock Mopar ones I've seen were external diaphrams. When those get old, they can leak and cause problems.

Then they act as a vacuum leak (tending to make the mixture leaner all the time) and don't pull the choke open (making the mixture very rich when cold). You can't adjust that out, but the 1st time I had that happen the Dodge dealership tried to adjust it out and just gave the car back that way. That experience greatly discouraged me from ever having any work ever done by a Dodge dealership again.

Thanks for the time and effort trying to "roll back the frontiers of ignorance" for me, Dan. I understand you to be saying that many carbs have a heating element in the black can holding the coil, yet the modulator for the heater is external on the block. My distinction between stock and kit is based on seeing the kit modulator in the thread you referenced, but seeing and reading about my specific carbs, Holley 8007 and Edelbrock 1404,that seem to be saying no modulator is needed, just plug current directly to carb.

For example, from the Holley 8007 (390 cfm) instruction web page at

http://www.holley.com/data/Products/Tec ... 8108-2.pdf

We find the hookup to say: "The long wire should be secured to the positive (+) terminal on the choke cap, with the other end connected to an ignition activated 12V source."

Absent an external modulator it seemed to me the constant current applied to the internal heater would keep the coil spring hotter and hotter until one turned the ignition switch off. If I understand correctly you are saying that some carbs (maybe such as the two above) DON'T need an external modulator because they have an internal modulator as well as a heating element.

Realizing I am putting words in your mouth by restating this way, it seems one could then do ONLY what the instructions say, hook a 12 volt "hot" line to the round black spring can's (+) terminal, then hookup the ground, and things will work fine.

Is that correct? (And I sure apologize for having to extend the inquiry to get the answer right for me!

Thanks
rock
'64d100