A thermoquad is not a mixer that I'd want to use for a learning experience! They were never designed to really be serviced, and were considered throwaways just like the Holley 22xx series. A total smog design carb for vehicle apps at a period in time when the domestic auto industry was in total turmoil and upheaval due to then massive intrusion of the federal government in nearly all aspects.
The urban myth regarding the thermoplastic body "warp" is an issue I've never encountered, the real issues are always something else. I have many of these carb cores and bodies, the bodies have all been repaired to correct the manufacturing issue regarding the epoxy sealing of the fuel crossover well. That is the real issue with these carbs.
What I do struggle with is the fact that the entire metering system is contained in the bowl cover and when those passages are damaged by moisture intrusion/corrosion over time, there is simply no way to correct 'em. While we have produced some decent tq overhauls for customers, it's been a hugh financial loss on my end since I have to work these units over and over to make a decent one for customers, and that is imperative for our customers here at ihon.
There is no way the throttle body on a tq can "warp" unless it's simply abused when mounting, resulting in mounting ear breakage/cracking. If the mixer will not return the primary throttle shaft to a full idle position, then something is in a significant bind or heavily corroded. All the shafts in these carbs are teflon-coated.
It's also imperative that the correct base gasket/heat dam be used between the carb and the intake manifold to prevent throttle butterfly hang-up in the manifold plenum bores. Any tq kit contains a multitude of various gaskets which appear similar but are vastly differnt, they do not all interchange, the correct gasket for each location for each model must be used.
And of course, a strong return spring must be rigged along with a throttle cable that has no issues regarding kinking, frayed internals, etc.
Most issues regarding a carb that won't return to a consistent curb idle have to do with vacuum leaks and that have the idle mixtures really whacked out. Since the vacuum leaks can't be compensated.
A secondary issue regarding erratic idle is a distributor mechanical advance unit that is hanging up.
A tq must have one or both (if so equipped) vacuum choke pulloffs functional at all times. If the pulloff can't actuate the secondary throttle butterflies can't operate. It's very rare that I see a customer's tq come in for rebuild that has functional vacuum motors/pulloffs.
The knowledge base for the thermoquad is located here:
http://www.forums.IHPartsAmerica.com/carb-tech/1390-carter-thermoquad-spreadbore-stuff.html
