Thermoquad questions

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remytherat

remytherat

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Just picked up a thermoquad off a 72 340 along with the intake manifold.

For some reason, when I line up the carb with the holes on the intake, part of the throttle arm of the carb hits the intake, preventing it from sitting flat. Do I need a spacer, or am I just not seeing something?

Also the secondary air door has no spring tension whatsoever. I tried tightening it to no avail. This is my first thermoquad so I honestly don't really know what I'm doing.
 
The air door spring is sprung. Top will have to come off to fix. On the intake, I suspect it is not a 72 TQ intake. Pics would help to confirm. Maybe an earlier square bore intake?
 
Intake has paint remover on it atm

Its hitting the tall bit on the right side between the primary and secondary bores

A4576711-1BCA-4A04-A3C9-45A5EFD466FA.jpeg
 
The gasket used on these was significant. Was phenolic as well to insulate. That is a very nice intake to use. Looks to be a 71 model. I guess possibly a late 71. What is the carb number? Located left rear mounting pad.
 
408 swinger said:
The gasket used on these was significant. Was phenolic as well to insulate. That is a very nice intake to use. Looks to be a 71 model. I guess possibly a late 71. What is the carb number? Located left rear mounting pad.
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this right here. the base gaskets are like 5/16" thick. that might get you the clearance you need.
 
Yup, a ThermoQuad does not use your usual paper-thin gasket. Don't even think about trying to use anything else.
1696823128076.png
 
Another tip. The Thermoquad and Rochester Quadrajet do NOT take the same gasket. The Quadrajet gasket used on a Thermoquad will have a vacuum leak around the back of the secondaries, so it's important to get the correct one.
 
Couple of comments.
Air valve spring could be broken.....or it might just need adjusting. Adjust to 1.5 turns.
I rarely use the thick sandwich gasket, just a 1/16" base gasket. Never had a problem in45+ yrs of TQ usage.
Carb is a good model & looks to be in exc cond. Best 4bbl out there.

See my tip on this section for improving sec operation.
 
Not going to use any choke, and found the correct block off plate for the intake in a random bag the guy had. Just concerned with the throttle arm hitting the intake. Hopefully the thick gasket fixes that
 
remytherat said:
Not going to use any choke, and found the correct block off plate for the intake in a random bag the guy had. Just concerned with the throttle arm hitting the intake. Hopefully the thick gasket fixes that
Click to expand...
I'd run a choke. Your life will be a lot easier.
 
ch1ll said:
No, get this one and you will not be disappointed.

View attachment 1716151748


And if you paid $100 for the carb and manifold, you stole it.
That’s a $400 combo there east. The carb alone I would expect to pay $250.
If that is a 71 intake, I can’t see the part number, its the best of the stock intakes.
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Its a 72 california intake

Paid 220 for the lot
Intake was very rusty but I’m working on it

Excited to rid myself of the carter bbd!
 
The choke not hooked up will flop about and make life a misery.
 
408 swinger said:
The air door spring is sprung. Top will have to come off to fix. On the intake, I suspect it is not a 72 TQ intake. Pics would help to confirm. Maybe an earlier square bore intake?
Click to expand...
Took the top off, found the spring at the bottom of the float bowl. Reattached it and adjusted.

While I have the top off, what is a good baseline for float adjustment? This carb has plastic floats (seemingly brand new).
Carb is very clean, I think someone rebuilt it and never ran it.
 
remytherat said:
Took the top off, found the spring at the bottom of the float bowl. Reattached it and adjusted.

While I have the top off, what is a good baseline for float adjustment? This carb has plastic floats (seemingly brand new).
Carb is very clean, I think someone rebuilt it and never ran it.
Click to expand...
29/32. Invert the top, measure from gasket to upper front corner of float. A Google search, or, a search here should get you a diagram.
 
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