Thermoquad

[Paul G]

I am really surprised at how well that old Thermoquad carb performs. It was on the 78 motor home 440 I picked up for rebuild. I decided to have some fun with the Thermoquad.

My 49 Plymouth has a 318, 4spd manual trans with an Eddy dual pattern intake using a Holley 600. It runs pretty well. For kicks, and since I have never played with a TQ I rebuilt it and put it on the Plymouth since the intake can accept the spread bore pattern. This TQ has the larger primaries, so it is the larger of the two most common TQ's. Am I surprised! The TQ kicks but. It feels like a different car. Smoother, pulls harder, better throttle response, just a sweet carb.

From the info I could find on the net these carbs are between 800 and 850 CFM. How do they work in a performance application today?    

[c00nhunterjoe]

 the knickname- thermobog. But like anything, with patience, its just a metered fuel leak. They are what YOU make them

[440]

Is that the TQ with bakelight body?

[TommyGun]

https://www.youtube.com/watch?v=OIsg3gMB6tc

[Paul G]

Is that the TQ with bakelight body?

Yes it is

[440]

They used them on small block Fords here and they weren't too bad. Many reckon they went harder than a holley 4 barrel but that could come down to tuning.

The only real problem with them was when people converted to dual fuel (propane) and the engine backfired it would crack them and leak fuel everywhere, eventually becoming illegal to use with propane conversions.

[Dino]

Best carb I had on my car no doubt. Took a while to get it right but once I did it woke up the car significantly.

But they have EFI now so this is just a paper weight.       

[flyinlow]

I have used Theromoquads.  I had one on a Street dominator equipted 446.


Pros:  good power (850cfm), good drivability, no hot start issues as long as the o rings where good.

Cons: Marginal accelerator pump shot for large unheated intakes, very limited parts and support, require a spread bore intake.

I tried larger pump nozzles, but still would gasp for an instant on cool days. Tried air valve adjustments too.

Finally replaced with a Quick fuel 780VS. Nice carb with Holley style accelerator pump. 

Demon makes a TQ copy now that uses Edelbrock jets and parts. Theirs is 750 cfm ,which is what a lot of the Quadrajets where. Thought about it but went EFI

[69Chrgr]

I have used Theromoquads.  I had one on a Street dominator equipted 446.


Pros:  good power (850cfm), good drivability, no hot start issues as long as the o rings where good.

Cons: Marginal accelerator pump shot for large unheated intakes, very limited parts and support, require a spread bore intake.

I tried larger pump nozzles, but still would gasp for an instant on cool days. Tried air valve adjustments too.

Finally replaced with a Quick fuel 780VS. Nice carb with Holley style accelerator pump. 

Just reading this old thread on the Thermoquad. I have a customer that I just rebuilt and warmed over his 360 for his 79 Lil Red Express. Had Scott Smith at Harm Auto do the resto on the T-Quad, and it has hot start issues, like it's flooded. Starts great first thing in the morning. What are these o rings that you are referring to? Otherwise performs awesome, but hot start is unacceptable.
Demon makes a TQ copy now that uses Edelbrock jets and parts. Theirs is 750 cfm ,which is what a lot of the Quadrajets where. Thought about it but went EFI