Thermoquad 4 Barrel Carburetor (Part 3)

[@71bee383]

Yes, great job in explaining the functionality of these phenolic wonders! so many people have hated the good ol' T-Q simply because they didn't understand some very important features found on this well designed carb. I have re-built hundreds, maybe thousands, & I have only found 2-3 that had serious float bowl issues (mostly from being back-fired through multiple times or being pried on). another issue you'll hear about is the nylon bushing in the primary throttle shaft. this is RARELY found.

[@nassilvertone]

Nice job! Thanks1 Your videos are helping me figure out myTQ issues.

[@RockysRoadshow]

Greetings cocoa cabana....Good observation....The Jets that you see on the Primary side of my Thermoquad, are what most carburetor jets look like....Usually made of brass (or maybe even bronze?), with a threaded portion under the head of the jet, and, usually a slot on top of the jet to facilitate the installation or removal of said jet, by using a jet-tool, or a screwdriver that can straddle the full width of the jets head...The Thermoquads "Secondary-Jets" look like "Aliens!" lol....Take care

[@RockysRoadshow]

@nassilvertone Thanks for the nice comment my Friend! I just try to put things in simple terms, so the subject at hand, may be easier to understand.

[@RockysRoadshow]

@71bee383 Thanks for the kind gesture my Friend!......Nylon Bushing?......No "Holley here!"...lol...I almost went that far and found it?...I attempted to remove the primary throttle shaft on this one when I took it into custody, and tried the, Tighten, till the screw top breaks off routine!...and quit when the first screw was too seized!...and besides, I needed to have the primary throttle plates in place for all of these Videos!...lol...and...I can get 1700 CFM's on my engine...850 CFM's x2 lol

[@71bee383]

@RockysRoadshow yeah,No need to worry about those nylon bushings, as I have yet to find a T-Q that needs them replaced. they do make replacement brass bushings if you really want to tear that sucker down, and if your into the Quadrajet...that's a necessity! 1700 CFM's? that's some serious suckage! ;) I usually guesstimate the CFM rating with any alteration(s) I make. it's amazing how much power these carbs can create without running waaaaay to rich.

[@capecodcuda]

they look like motorcycle jets !

[@juannoria2285]

Im glad to have found your videos.. I have a few questions about this kind of carburetor.. Is there a way I can contact you with my questions??

[@RockysRoadshow]

Greetings...Juan Noria.........Thanks for watching.........Just post your questions, on any of my KZbin videos, and I'll do what I can, to help you out..........Do an internet search for...Vaanths Thermoquad Guide...and hopefully, there will be a website or two, that still has a link to it..........It's a very well written, and compiled web-page, that has lots of information, about the Thermoquad carburetor...........There are usually four numbers, followed by the letter S, that are stamped into, the lowest aluminum part of the Thermoquad carb, at the rear of it, and, those four numbers, along with the letter S, will be the proper identifier, for that particular model, of Thermoquad carburetor (some folks, have made the "mistake", of, using the numbers, and/or letters, that are found, on top of the Thermoquad carb's, top aluminum casting, just so Ya know).........In order to have a Thermoquad carb, function properly, as good, as it's able to, then, all parts & pieces of the Thermoquad, have to be in very good condition, and, all adjustments/settings, have to be done in the correct "sequence", as in, order of doing them, or else, the Thermoquad, probably won't be working, as good as it should be.........Also, today's gasoline (blend), that usually has about 10% Ethanol (alcohol) in it, can cause a Thermoquad carb, to administer a "leaner" air/fuel ratio, to the engine, which can be harmful, when going pedal-to-the-metal, and, I had to install larger fuel jets, to richen up the air/fuel ratio (mixture) a bit, in order to keep the engine safe, and happy too, and.......till next time.......Be Safe, take care, and have a good one.

[@juannoria2285]

What's the best way to set the mixture screws on the carburetor?

[@RockysRoadshow]

Greetings...Juan Noria........There are basically "2" ways, to adjust the idle mixture screws........One way, will be for a vehicle, that "does not" have to be smog/emissions tested, while the other way, will be for a vehicle, that "has to be", smog/emissions tested.........The good ole basic way, can be done with a vacuum gauge, or a fairly accurate tachometer (meter).........For a vehicle that has to be smog tested, I only use a tachometer, in order to do, what is called, the lean drop method.........The engine has to be at operating temperature (hot), choke fully off, the vehicle on level ground, having the tires blocked for safety, and, the automatic transmission in Park, or, the standard transmission in Neutral, for safety reasons..........Never stand in front of a vehicle, just in case it jumps into gear by itself...!!! (it happened, not too long ago, to a guy, that does mechanical work).........The basic setting (not for smog), is to get the engine to idle, with the idle "mixture" screws, at its highest idle speed, while the idle "speed" screw, is kept at the specified curb idle speed........As each idle mixture screw is turned in or out slowly, the engine RPM's will change, and, if turned in too far, the engine idle speed RPM's will drop, quite quickly.........Always keep the curb idle speed, at its specified RPM's, with the idle "speed" screw (might be, about 600 RPM's, as an example)..........Look for a label or sticker, in your engine compartment, that will show the curb idle speed specification, but note, that, it might be specified, while the transmission is in Drive, so, for safety, I just make the adjustment, while in Park, at, about 100 RPM's higher than that specification, and, once I'm done, setting the idle mixture screws, I will then go, sit in the drivers seat, push on the brake pedal, put it in Drive, and look at the tachometer, while it's facing the windshield, to see how close I am, to the in-gear, curb idle speed.........If I'm a bit too high, or, a bit too low, in RPM's, I put it back in Park, and re-adjust the idle "speed" setting, and I only check that curb idle speed, with me, sitting in the driver's seat, with the foot brake on, for safety reasons...!!!.........Some vehicles, will have that label or sticker, stuck somewhere in the engine compartment, and, can sometimes be called, a V.E.C.I. (Vehicle Emission Control Information) as I recall, and, on some of them, there might be, that, required for smog/emissions testing, "Lean Drop" specification, that I was talkin' about earlier.........As an "example only" for Ya, then, I would do the basic idle mixture screw settings, with a tachometer, at the specified RPM's, as per, that good ole V.E.C.I. sticker, then, only turn in "equally" and slowly, the two idle mixture screws, until the idle RPM's "dropped", exactly 100 RPM's, as per, the specification, that was printed on, that particular V.E.C.I. sticker (this basically just leans out the idle mixture a bit, which is required, so the engine's exhaust gas, is within, the emission testing station's, allowable limits, for that particular vehicle).........For a vehicle that "does not" have to be smog tested, then, a vacuum gauge, is a really good, old school way, of adjusting the idle mixture screws, but, to keep the curb idle "speed" accurate, then, Ya still need a Tachometer for those curb idle speed RPM's, or maybe, if Ya have a good ear, for those quite low RPM's, then, that can be done as well........If it's an automatic transmission vehicle, then, don't allow the curb idle speed RPM's, to get too high, or, the vehicle will usually "creep" along, too fast, as soon, as Ya take your foot, off of the brake pedal, while your foot, is not even on the gas pedal yet...!!!...and.......till next time.......Be Safe, take care, and have a good one.