TQ jetting

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racingsnake440

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Does anyone have any suggestions for a starting point for jets/rods in the TQ for my Dart? It's a 318 out of a '71 Dart, stock internally with a Weiand dual plane intake, no EGR or air pump, recurved electronic distributor and Magnum manifolds with dual exhaust.

I've looked at the Vaanth TQ guide but the only 318 jet sizes it lists are for late '70s cars which I assume may be lean burn and so jetted differently? The carb I'm going to be using is originally from a '75 360.

Thanks
 
I'd toss that carb back on the shelf and get a holley or carter/eddy.

not a lot thats readily available for those.


Try DemonSizzler search here and on the net and pm/email him, he likes to play with these things.
 
A tq is a great carb on a 318,but as mentioned not too much for parts these days.Try buying some used tq's so you have spare jets/rods etc. I have about 6 and one of these is rebult.So far I havent needed spare parts,but I can noe drill jets with bo worries. You will also need numbered drill bits and a drill press.

Demonsizzler is an expert on these carbs.

Carter carbs by Dave Emanuel is a good book also. Im not familiar with the book/manual you mentioned?

I also have a manual in pdf format for the 72 tq. If you want it,pm me.
 
I've got a pile of old TQs and loads of spare jets so I figure I ought to have something that works. I've got the Carter book but didn't recall it having much on TQs - I'll have to take another look.

The Vaanth guide is on the net - I forget where I found it.

I'll give DemonSizzler a try too.

Thanks
 
I'd start with the stock jetting for the earliest 318 application I could find. It may take a rod step rich, possibly 2 step richer if you have that many rods in the small steps richer.
 
First, be sure your manifold will accept a spreadbore and the bolt pattern. If OK, and you want to make the TQ work, do it later after you get a newer carb. set up, like the ones 1wild&crazy guy said. Then you'll have something good to compare with the TQ. Cause it might become a hassle, with the parts.
I like the TQ, with those small primaries they're a good street carb. for sure. I had one on a 71-340 Duster. From stock, I had to give it more air and fuel and adjust the air valve. That made it work.
I never used this guy's service, but I saw him mentioned on this site. You might try him. http://thermoquads.com/
 
Im a huge tq fan when the motor is fairly stock. Maybe higher compression,headers and a cam. After this I'd go to a Holley.

I know there are racers running in the low 11 sec range with tq's on thier motors. Done for class restrictions I guess.
 
I have to agree with the "put it on the shelf" recommendation. I tried running a ThermoQuad (originally '83 360 carb) on my 318 when I rebuilt the top end but the secondaries simply did not work no matter how I attempted to tune it. I fiddled with it but in the end it was either spend $100 for a nice used Edelbrock/Carter carb or spend $250 on a professional rebuild and tuning for the TQ to make the damn thing work. Now I'm running a 625 AFB and it works great but when I do a full rebuild for my 318 I'm going to spend the money and get a proper ThermoQuad. I just want that extra edge in gas mileage.
 
If it is a lean burn carb I would not use it, if it happens to non leanburn it would be a decent carb, and I'd start with stock jetting and the adjustments suggested on demon sizzlers page. thermoquads.com
 
I was just about to say the same ting babyblue said. The smogger T-Q's, as stock on a non stock engine aren't the best idea in the world to use. The modern Edelbrocks and Holleys would be my choice to use.

The T-Q's from the smog years cn be modifed to work, but they are a pain to dial in since theres a ton of adjustment points to consider and make sure there correct.

I like the T-Q. But you do have to take your time with it and fiddle with it to learn it. While, in a sense, a carb is a carb, you just can't throw them on and expect magic.
 
Rumblefish - any idea where I could find the stock jetting for an early 318 TQ application - the earliest I've found is late 70s which I suspect may be lean burn.

I'm already running a TQ on the car but it's worn around the throttle shafts and leaks gas - other than that it doesn't run too bad but I think it could get better mileage.

Basically I've got no money but plenty of parts and time to mess with them so just wanted a starting point to put the replacement carb together at.
 
I used to call them thermo bogs. The plastic body always warped. But I loved the sound and response when it was tuned just right. Those huge secondarys would kick in and boom. But still not enough reason to run with one. Too much work.
 
Block off the heat cross over to help keep the carb cool and that warping problem won't happen.

I don't know what rod and jet specs to give you since I don't know what T-Q 's came on 318's. Number on the drivers rear pad would be the number I'm looking for.

Use what you have and work it from there.
 
racingsnake440 said:
I'm already running a TQ on the car but it's worn around the throttle shafts and leaks gas - other than that it doesn't run too bad but I think it could get better mileage.
Click to expand...

If its leaking the needle and seats are bad, or the 2 small epoxied pieces on the bottom of the phenolic body may have begun to leak. I had to reglue these on 2 Thermoquads to keep them from flooding out as fuel starts to leak into the base plate. This could be the poor mileage problem as well.
Also the 2 o-rings that fit into the recesses of the plastic body between the top plate have given me an over rich problem as well.

A worn shaft will not cause a leak.
 
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