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THERMOQUAD!!!!!!!!!

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Ifitaintbroke

THERMOQUAD!!!!!!!!!

Anyone here know how to tune one of these strange mythical creatures? Ie: what do all of the different screws and linkages do exactly? And, finally, can one support 500+ horsepower? I think that it can, being that it is over 800 cfm. Any advice would be appreciated.

Note: I don't currently have an engine to run it on to test it. It is freshly rebuilt though.

Bradley
86 f250 supercab longbed, 4x4, 460 bored to 472 cubes, ported heads, ARP rod bolts, EFI pistons, 5.08/5.41 lift 114° lobe separation flat tappet cam, notched lifters, Smith Brothers pushrods, stock rockers, Eddy Performer intake, Holley 1850 or 3310 depending on mood, custom curved points dizzy, MSD analog 6al triggered by Pertronix module, zf5 swap, 3g alternator, custom instrument cluster, dual tanks with 38 Gal rear for 57 Gal of fuel capacity, far too much more to mention.

98 Ranger standard cab, rwd, 5-speed, 2.5L, glass pack muffler, dual plugs wired to fire at the same time, coming up on 300,000 miles before too long.

Averaging 26-27 mpg.

South Georgia.

Gary Lewis

Re: THERMOQUAD!!!!!!!!!

Administrator

You need Bill/85lebaront2 to help you. I'll tag him. But having run a carb/ignition shop for decades I'm sure he knows.

Not sure about 500+ HP, but they were rated at 800 or 850 CFM. Should have a lot of flow, and Chrysler used them on the 440's.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

85lebaront2

Re: THERMOQUAD!!!!!!!!!

Administrator

In reply to this post by Ifitaintbroke

First, it depends on which of the three styles of Thermoquad you have. The original TQ was an aftermarket only performance carburetor, offered in 850 and 1000 CFM. numbers are 4846S or SA for 850 CFM and 4847S or SA for 1000 cfm. The difference in the S and SA, the S models had pressed in jets, the SA had screw in jets. These were part of Carter's Competition series of carburetors. The first batch of OEM TQs were referred to as "air bled" as the metering system used air bleeds to help emulsify the fuel better, they were later changed to "solid fuel" versions.

These OEM TQs were primarily Chrysler corporation applications (link below has the numbers, kits and jetting information) Ford used a TQ on the 1974 CA spec 460s and IHC used them also. The first versions had a vacuum only controlled metering (or as Carter called them step up rods), with the OEM applications, a cam in the throttle body and a long adjustable rod in the step up piston were added. This was particularly needed on the lean burn Chrysler engines as they ran on the ragged edge of lean misfire.

Some very important items, bowl is plastic, a stuck primary main jet can ruin it trying to break it loose, under the main jets, are two little channels that fuel flows through between the jet and the metering passages in the bowl cover/air horn. These have small covers that are epoxied on from the factory. The sometimes leak. Last, the seal between the bowl cover primary metering wells and the bowl was originally an O-ring, due to leaks it was superseded by a molded two sided lip seal (you should have seen the Chrysler Newport wagon with the seals missing from the factory according to the dealer who towed it by the back bumper 30 miles to my shop) gas tank was almost dry, dipstick showed oil was way up it.

https://carbkitsource.com/tech/Carter/pages/tqguide-Vaanth.html#:~:text=The%20Thermo%2DQuad%20was%20available,rated%20at%20800%2D850%20CFM.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

Ifitaintbroke

Re: THERMOQUAD!!!!!!!!!

In reply to this post by Gary Lewis

Why oh why oh why must carburetion always be so complicated? The TQ I have is of ~75 vintage, and was originally intended for a 400 with an automatic. I think it was for a car application like a Monaco or something. Bill, do you know much about how to tune one? I'd like to least try the silly thing, since if have so much work in it. With this build, I REALLY want to use a spread bore carb. Manifold I'm using is a Performer RPM, which has a dual pattern and can accept both spread and square. Also been looking at Q-Jets, as they will be much easier to find someone to tune them. Could also use a spread bore Holley. I also just like to be different.

Ifitaintbroke

Re: THERMOQUAD!!!!!!!!!

Also, know where to find a CS TQ? I'm sure they're scare as hens' teeth, and worth their weight in gold when found.

85lebaront2

Re: THERMOQUAD!!!!!!!!!

Administrator

This post was updated on .

In reply to this post by Ifitaintbroke

With or without looking at it? Just joking, yes, I can tune them, as for size, that link I thought had CFM ratings in it. Ok it wasn't that one, I will look again tomorrow as I did find a list with CFM. Holley Spread Bore, you'll give Gary a heart attack. They do well if matched up to the engine.

Here is the link with sizes:
https://www.carburetor-blog.com/knowledge-base/tq-specs/

85lebaront2

Re: THERMOQUAD!!!!!!!!!

Administrator

V10 throttle body same bolt pattern as a 460, holes just need enlarging from an M6 clearance hole to an M8. Configuration is the sme, cable on right side TPS on left. $5 at Pick-n-Pull vs what an aftermarket one costs.

On the strip kit, I believe I saw right around $450.

Bill AKA "LOBO" Profile