Whats a good replacement carb for the Thermoquad?

[WH23G3G]

I never could get this old Thermoquad on my 73 400 running reliable enough and I'm tired of messing with it. I guess with someone who really knows how to tune it they could get it running pretty good. But unfortunately there's no one like that in my area. It maybe just too old and worn out to fix without a full remanufacturing. So I'm debating whether to do that, buy a fully remanufactured Thermoquad or upgrade to a new Edelbrock. I want to put an Edelbrock on here but I don't want to have to modify anything. I've got the stock 73 iron manifold and all new OEM stainless fuel lines and a new engine harness. I guess I wouldnt really have to mess up the fuel line, I could just remove the one from the filter to the carb and replace it with a custom one to the Edelbrock fuel line fitting. Then there's the question of the choke. I know you can get electric choke, but would I have to cut or splice anything into my harness because the original has the electric choke heater. Is there a bolt on replacement? How do I know which one to get? It's a .040 over 400 with a Sealed Power replacement cam, stock ignition, and factory HP manifolds. How many CFM would I need? What modifications will I have to do?   

[NorwayCharger]

How about this?

[Chryco Psycho]

I would not use a Demon on anything . horrible quality control .
Holley has a series of bolt on Spread bore carbs , the TQ is 800 CFM , I would suggest something similar in size

[WH23G3G]

I've heard Edelbrock's have the best idle quality. I knew of a guy with a Camaro that had a shop out one on a well used 327 and it started up with two pumps of the pedal and idled smoother than my fuel injected daily driver truck. Should I use the Thunder Series AVS Edelbrock carbs? I only hear good things about the Edelbrock and see most of them on engines at car shows, rather than Holley.

[71ChallengeHer]

I hated my Edelbrock carb. Chryco tried to dial it in at Carlisle a couple years ago. And he didn't have any luck with it . I replaced it with a Holley. I'm very happy with it. 

[Chryco Psycho]

You see a lot of cars with BFG tires at shows too but you will never see them on my car , they may be safe sitting still just like the carbs

[WH23G3G]

I've heard Holley's leak a lot. I'm going to want to still use my factory air cleaner. Would it be possible with any aftermarket carb?

[Fred]

I've heard Holley's leak a lot. I'm going to want to still use my factory air cleaner. Would it be possible with any aftermarket carb?

Yes, no problem.

[Dino]

My eddy has great idle and I trust the car to take me anywhere.  That said it runs rich on idle and lean at wot.  Bogs are common as with most these things so this is my first and last.

I'm actually going to the thermoquad next.  If you can rebuild yours then it might solve your problems.  Doesn't hurt to try and will certainly not break the bank.

[charger_fan_4ever]

Holley 4150 DP carbs are super easy to tune and a must with any kind of performace engine.

Pick up a used 750 check the throttle shafts make sure they are tight. If they are loose vacuum leaks and make sure the baseplate isn't warped and your good to go.

[Nacho-RT74]

yes of course... with another TQ LOL

[WH23G3G]

I went to Summit Racing tonight and they actually had 3 Thermoquads remanufactured by Holley. So I bought one but when I got home I noticed that the Holley part number was 64-1436 and thats for a 440 but I have a 400. So the Holley part number should be a 64-1203 which Summit said is no longer available.  The one I got casting's number is 6322S which is for a 440. I know the jets were different on 440's than on the 400's well at least the secondaries. Should I even try to install and run this carburetor? Will it ever idle and run right? It's bored over .040 does that make a difference? Its got stock ignition, stock intake, stock hp exhaust manifolds, Sealed Power OEM replacement camshaft. Do you think this Holley reman carb will work good? They also suggessted a 650 or 750 Edelbrock AVS if I wanted to go with aftermarket. They punched in 6000 RPM redline on a CFM calculator. Any suggesstions?     

[Nacho-RT74]

I have been runing a 440 carb on my 400 since ever. If interested or worried, you can readjust some of it, like switch the metering rods and readjust secondary air valve. Not a big deal

[TooMuchTime]

If you are having problems with your ThermoQuad and it just needs a rebuild, I suggest you go here:

Rebuilding A Carter ThermoQuad Carburetor

There is a full article which has some very good instructions on the cleaning and rebuild, and there is a link at the bottom that says See All 14 Photos. Click on that for some detailed info. Probably the most important is Photo Number 7 and the information on the buckets under the main wells of the phenolic body. Since they were bonded in place during manufacture, you need to make sure that the bonding agent hasn't failed. It's an easy thing to skip and if forgotten, could make the carb rebuild for naught.

Carter and Chrysler claimed the ThermoQuads kept the fuel about 20 degrees cooler than a standard all metal carb. Don't know if that's true but it does keep the fuel somewhat cooler and that's not a bad thing. The "minuscule" primaries are pretty good for reasonable mileage around town. Just don't rabbit from every stop light. Nice economical driving will keep the mileage at acceptable levels. Well, for a V8 anyway. But when you stand on it, those massive secondaries open and you get 800-850 CFM (depending on the model). And that throaty TQ roar to boot!

Hope this helps.

[rick]

I bought a summit 600 secondary carb for my 383 put in on at 7000 ft altatued never had to adjust it. Drove it to omaha at 1200 ft altautued never touched it this thing runs like a top super carb for the price about 220.00 check it out