MTSC - 1972, Volume 72-1 The '72 Thermo-Quad Carburetor Chrysler is a registered trademark of Chrysler LLC. Master Tech series training manuals and videos are the property of Chrysler LLC.
Who ever is responsible for posting these videos, THANK YOU! You have taught the next generation of Mopar enthusiast how to do things the right way. If it wasn't for these slide shows, likely put together by the engineers and service factory service techs themselves, a lot of this stuff would be lot.
Most people who dislike TQ carburetors were simply too lazy to do all the adjustments, and IN THE RIGHT ORDER. Follow the book, set everything right, and it's really a great carb. 800CFM and no bogging, and a hell of a lot better fuel mileage than a Holley or older AVS/AFB Carter design.
This was a HIGHLY underrated Carburetor! I'm a Retired Auto Mechanic, from 78-06.... And Carburetor and Driveability Specialist. I've always heard them called "ThermoJUNK" and a few other names. These and Quadrajets, we're actually fantastic Carbs!! They both gave fantastic high end performance, with excellent low speed Driveability and respectable Emissions... AND size for size, got BETTER fuel economy than ANY square bore Carb! I Raced too. I was the first (in my area) to go 12s with a Quadrajet! (FAST was slower than it is today!!) 😜 That was a BIG deal back in the day. Now as in then, it's ALL about Tuning. True, Thermoquads needed a specific adjustment order. But get it right, and they were great performers. I tuned one for a friend's 74 Challenger 360. He was sure he needed a Holley, so he bought one. Ran fine, but WOULDN'T pass smog testing, and kept blowing Power Valves!! He averaged 12mpg also. I built him a Thermoquad and set it up. He PASSED Emissions, got 17mpg, and GAINED 1/2 second in the quarter!!! 😲 That's because his Holley (when NOT blowing Power Valves) was 600cfm, and most Spreadbore Carburetors were 750-850cfm!! 😎
@@ernestgoble8825 Well Ernie..... Nothing is harder than diagnosis without seeing and hearing. Things I would check.... Ignition Timing. Try advancing 2-3 degrees more than specifications. Spark Plugs. Replace them with one Heat Range higher than stock. Check Cap, Rotor and Wires for damage, check Wires for resistance. If they're more than 5 years old - REPLACE. THEN Carburetor. How old is it? Rebuilt? Disconnect and plug the Vacuum Advance Hose from the Distributor. Adjust Idle Mixture, with a Vacuum Gauge. Turn both screws in all the way, LIGHTLY. Too much force will enlarge the holes, and the Carburetor will be JUNK. Then turn both Screws out exactly 2 1/2 turns each. With the Vacuum Gauge connected, start the Engine, turn each Screw in 1/8th turn at a time, EVENLY.... You want both sides to always have the same adjustment. Watching the Vacuum Gauge, turn the Screws until you get the highest Vacuum reading at Idle. If you still can't get a smooth Idle, with at least 18 inches of Vacuum.... It's something deeper. Intake Gasket leaks, bad EGR Valve, leaky Valves, Head Gaskets, Rings.... Sorry it's not easy, but it's rarely ONE thing, unless a perfect running Engine all of a sudden started messing up.
..... One "cheat", SOMETIMES new Catalytic Converters can get you past Smog!! If your Truck never came with them, it's legal to do, because it's a LATER Model upgrade. 😉
@@ernestgoble8825 Did those engines come with a maze of vacuum operated smog devices? It wouldn't surprise me if some of them aren't working. Even when those engines were a few years old, half of that stuff wasn't working. Does yours have an exhaust air pump? It would be wise to check the diaphragms and pump to make sure they function. The added air when combined with exhaust heat will reignite unburned and partially burned gasoline vapors.
I have messed with a few TQs in my time. Although 26 years of my experience was at a Ford dealership, we did have customers who also owned motorhomes they brought to the shop for repairs. Some were built on Dodge chassis with a 440 engine. I do remember the TQ carb was very finicky and required a great deal of patience; but that's true for most carbs. I do recall one that had a warped body and would not stop leaking. The mechanic working on it took it apart 3 or 4 times trying to stop the leak before using a straight edge on the plastic body; sure enough it was warped. Finding a replacement body was a challenge; this was pre-internet days and our location was in the middle of nowhere. Eventually we found one and looked like heroes once John repaired the carb for the last time
I have 3 of the infamous Carter Thermoquads, they worked pretty good once tuned right, my problem was that plastic bowl, hot/cold weather, it would contract/expand, they developed cracks, other wise, with those big secondaries, whatever the carburetor sat on top of what Mopar motor, GODDAMMIT, sounded mean as hell!!! Mopar Nate Philadelphia, Pennsylvania
The vac pulloff is perhaps the most crucial adjustment. Aside from that, dump the closed foam floats for brass 1s. 8 times out of ten, you won't need to bend or adjust anything during a rebuild.
I have worked on these back in the 80's & 90's when I was driving those old 70's Mopars! I did my 1st rebuild on a '79 Newport 360 Hi-po police engine. I did it off the "instructions" listed on the aftermarket rebuild kit. So no real instructions when I performed it! It took 3-4 disassembly tries before before it seemed to run right, lol. Mileage was better at 15 mpg vs. 11-12 mpg beforehand, but the 4 barrel "kick" still had a terrible stumble. I found out eventually that the choke vacuum kicker was what controlled it. But even after installing a new kicker it still stumbled. I guess I didn't have the correct instruction available to me to set it up right... Later as I gotten older and more experienced with carbs, I had taken apart 3 other T-quads with much better results...;-).
The choke on these were junk. Everything else was great, but when they went with the Qjet in the '85 - '89 squads, all the tuning and drivability problems went away. The Qjet was a little smaller (750) than the TQ, and could not be set up as lean, but they were very good in cold weather.
i know this is a old post but i run a 850 on my 440 they are very picky but once you under stand them they work very well i get 11 mpg which dont sound good but thats in a 1973 dodge D 100 club cab with a 727 loadflight trans and 355 rear gears
My father calls the thermoquad a thermojunk to this day.It was a pain to adjust,could not get it adjusted right.My father does like Chrysler products.He remembers working on them.
Plus the screws never came out.Last one was in a 1985 Dodge Ram Charger,could not get the screws out.Threw it in the scrap pile and replaced it with an Edelbrock carb
wafrederick The TQ was gone by '85. The QJet replaced it. The TQ is a thousand times the carb that the Eddie is - why do you think Carter replaced those old AFB/AVS carbs with the TQ in the first place ???
Considering the TQ didn't come standard until after the Hemi and 6-Barrel engines went away, and the price of fuel went through the roof beginning in 1974, I sincerely doubt many were actually replaced with horrible Holly.
