The Stovebolt Site Forums The Shop Area The HiPo Shop Carter thermoquad performance carburetor

There was mention of the use of a Rochester Q-Jet in another thread, and I brought up the Carter TQ (thermoquad) as an alternative to the Q-Jet.

The easy way to do this was to put it on my website with a link.

If one has a V-8, especially a performance V-8, then the thermoquad is at least worth a look.

If there are questions, will try to answer them.

The Carter TQ (thermoquad) performance carburetor

Jon

Good info here Jon, thank you. I had only one chance to work with a TQ, that may have been 1972-1973, friend loaned me a TQ to try on my 1967 C10, 396, powerglide. It was no better than the Q-Jet as far as keeping rear tires from melting and transmission bands from burning. I didn't know what to blame!

Not sure if I have done more TQ's or Q-Jets, literally hundreds of both. Both are great carburetors.

I replaced the Q-Jet on my 350 with a TQ. First gear, with the TQ, is totally useless if the vehicle is driven in anger. Engine rev's, vehicle not does move (except the rear wheels/tires).

Jon

Thermoquads are fine carbs, I used to run a Thermoquad on my '70 340 Duster. It's original carb was a Carter AVS, the Thermoquad was MUCH better. At the time I was running 4.56 gears along with a set of 7" slicks (biggest you could run in NHRA E-Stock) back in the early 70's. Low 13's (with a rare high 12) at 105 were not too hard to get too. Later moved up to a 1000 cfm competition TQ, Way over carbureted based on the math, but it did go faster, so go figure but not fast enough to get near the E-Stock record of 12..56. Biggest thing that made the combo work was the TQ's easily adjusted vacuum secondaries. They didn't come in until you could use em. I think I've still got a TQ Carter strip kit or two in the shop.

RonR

Probably best not to discuss the AVS in a high performance forum

Jon

I've been looking for improvements for my 2 ton LCF, if I remove the governed 2G, stick a Thermoquad on there, maybe let some air out of the 14 ply 10R-22.5's, do you think it'll get down the drag strip at 13 seconds???? The SM420 is a little slow in the gear rowing department but I do have drag gears in the rear end, it's like a quick change only you don't have to get the tools out. Or maybe I should just leave well enough alone and try not to scatter the little 283, 62-65 mph at 4000 rpm is good enough.

I have done a lot of carbs in my days mostly Q-jets. The TQ is one I never much got into. It seems like they were hard to get right. That "lean burn" system Mopar came out with in the 70's was the worst idea ever put in an engine.

George

George - maybe not the worst, but it certainly makes the top 10!!! It came out in 1975.

The lean burn carbs were calibrated at about 18.2:1.

Carter told Chrysler if these were to work at that A/F the temperature of incoming air to the carburetor for idle must be controlled.

Chrysler had a snorkel with a trap door controlling the source of the incoming air for temperature purposes, that was controlled by a special valve.

The reliability of that valve resembled voting in Chicago (vote early, vote often). In the case of the valve, it was fail early, fail often.

The O.E. Chrysler carbs are best left to the Chrysler enthusiasts unless one stumbles across some at a swap meet CHEAP. Some came with brass (preferred) floats, others came with foam floats. The Chrysler versions (other than the 1971's) can act as donors for metering rods, floats, and maybe some other parts for the 9000 series aftermarket units.

Jon