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best replacement carb for a thermo quad

Posted By: dartman366

best replacement carb for a thermo quad - 07/03/10 12:08 PM

got one on my motorhome/tow barge that need's a serious pitch in the junk pile and was curious what some of you guy's reccomend, I was thinking about a Holley spreadbore or even a Edelbrock performer,,, the holley I can work on, the Edelbrock works real good if tuned in correctly ,,,so I was told,,,,so let's hear it.
Posted By: blownzoom440

Re: best replacement carb for a thermo quad - 07/03/10 12:17 PM

a vac holley 600 comes to mind.mite be cost effective also.
Posted By: Chris2581

Re: best replacement carb for a thermo quad - 07/03/10 01:15 PM

Holley spreadbore would be my choice.The other thing I would consider is having the TQ you have now rebuilt or have one done up by DemonSizzler.
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/03/10 03:09 PM

wouldn't a 600 choke a 440 too much?,, Jeg's has a 650 spread bore, vac secondary,,I even thought about a 750 vac secondary.
Posted By: Chris2581

Re: best replacement carb for a thermo quad - 07/03/10 03:11 PM

I don't think it would at all.Remember the TQ you have now is rated at 800 or more cfm.I think the 650 spreadbore would do just fine.
Posted By: dannysbee

Re: best replacement carb for a thermo quad - 07/03/10 03:15 PM

A well built and tuned thermo quad would be the best choice for replacement in my opinion.
Posted By: Thumperdart

Re: best replacement carb for a thermo quad - 07/03/10 03:19 PM

Quote:

A well built and tuned thermo quad would be the best choice for replacement in my opinion.

I`ve built several of those for race cars,trucks and motorhomes and all worked well when tuned properly. There`s a trick to makin em work and not bog and it starts with the metering rods and ends w/the air door adjustement......and of course a few tricks in between.
Posted By: StripeHOG

Re: best replacement carb for a thermo quad - 07/03/10 03:23 PM

put a Q-Jet on it and forget about it
Posted By: dannysbee

Re: best replacement carb for a thermo quad - 07/03/10 03:42 PM

Nothing wrong with a Q-Jet, or a Holley but why settle for second or third best?
Posted By: dOoC

Re: best replacement carb for a thermo quad - 07/03/10 04:04 PM

Quote:

got one on my motorhome/tow barge that need's a serious pitch in the junk pile and was curious what some of you guy's reccomend, I was thinking about a Holley spreadbore or even a Edelbrock performer,,, the holley I can work on, the Edelbrock works real good if tuned in correctly ,,,so I was told,,,,so let's hear it.



PITCH IT ....right over here ...I beez the Prez of the ThermoSquad !
Posted By: Bob_Coomer

Re: best replacement carb for a thermo quad - 07/03/10 04:13 PM

Hey Bill
I have a spread bore 600/650 Double pumper Holley I have $75 in...you can have it for that...
its pretty clean, but I havent run it and it needs a kit.
The carb is a single line side hung bowl 600- or 650 Double pumper...
Havent seen many like this..
Came off a late 60's big block Pontiac..
Posted By: HotRodDave

Re: best replacement carb for a thermo quad - 07/03/10 06:08 PM

The T-quad that is sposed tobe on there is an 850. If you put an 850 holley on there it will not run near as good. Just fix the t-quad, it will run better and get much better mpg. Remember under hood temp on a 440 running peadl to the metal in a MH is pretty high so the plastic carb will work wonders.
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/03/10 09:09 PM

Quote:

Quote:

A well built and tuned thermo quad would be the best choice for replacement in my opinion.

I`ve built several of those for race cars,trucks and motorhomes and all worked well when tuned properly. There`s a trick to makin em work and not bog and it starts with the metering rods and ends w/the air door adjustement......and of course a few tricks in between.

That's the problem,,,I know nothing about a TQ, or the trick's to make them work right.
Posted By: dOoC

Re: best replacement carb for a thermo quad - 07/03/10 10:11 PM

Quote:



That's the problem,,,I know nothing about a TQ, or the trick's to make them work right.



What are the probs you are having ?
Posted By: Leigh

Re: best replacement carb for a thermo quad - 07/03/10 10:16 PM

They are pretty straight forward. Floats and vaccum diaphrams were always a problem. Sold a few main bodies, too, so I'm not so sold on the MH cooking that deal. Probably ok. If it's a good core, try rebuilding it first.
Posted By: Thumperdart

Re: best replacement carb for a thermo quad - 07/04/10 12:00 AM

Quote:

Quote:

Quote:

A well built and tuned thermo quad would be the best choice for replacement in my opinion.

I`ve built several of those for race cars,trucks and motorhomes and all worked well when tuned properly. There`s a trick to makin em work and not bog and it starts with the metering rods and ends w/the air door adjustement......and of course a few tricks in between.

That's the problem,,,I know nothing about a TQ, or the trick's to make them work right.

See if a local shop can re-build it for you and if not, send it to me and I do it for ya. One major trick is to epoxy the jet wells in the plastic body as they leak and reak havock on the driving/tuning issues those carbs have.
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/04/10 12:48 AM

Quote:

Quote:



That's the problem,,,I know nothing about a TQ, or the trick's to make them work right.



What are the probs you are having ?

If it sit's more than a week you have to prime the carb with gas to start it, no amount of pumping the accelerator give's it enough gas to start,, act's like the bowl's are completely dry,,,won't go into 4 barrel mode when pedal is slammed to the floor, run's on 2 barrel only,,,idle adjustment screw's have no effect on idle quality,,,and it is just a scuzzy, scurvey, nasty looking mess,,I just want to make sure all is good and ready to go with the best economy that I can get from this barge.
Posted By: dulcich

Re: best replacement carb for a thermo quad - 07/04/10 01:33 AM

A better carburetor than the Thermoquad has yet to be invented. It was truely the finest moment for cabureted fuel delivery.
-dulcich
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/04/10 02:04 AM

Quote:

A better carburetor than the Thermoquad has yet to be invented. It was truely the finest moment for cabureted fuel delivery.
-dulcich

Thank's Steve, now where is the best place to obtain info on how these thing's work and how to modify and tune them,,guess I need to start lern'in how.
Posted By: dulcich

Re: best replacement carb for a thermo quad - 07/04/10 02:23 AM

Unfortunately, if that's your aim, you've got a hard row to hoe my friend.
-dulcich
Posted By: junkyardmaxie

Re: best replacement carb for a thermo quad - 07/04/10 03:36 AM

Bill there was a guy posted a holley 750 vac secondary rebuilt for $125.00 also had another carb edelbrock, on same post. i think it was in race parts for sale, or mopar motors big blocks Bob
Posted By: ademon

Re: best replacement carb for a thermo quad - 07/04/10 03:46 AM

if its going back on your stock MH rebuild stock, but for performance get a bunch of # drill bits, bunch of jets, rods, sec jets, and start drilling on your lathe, no aftermarket help for jets or bigger seats, i got the one in the pic working good but the 750 holley carb with annular boosters was still better.

Attached picture 6067737-party046(640x480).jpg
Posted By: rebel

Re: best replacement carb for a thermo quad - 07/04/10 06:15 AM

why hasn't anybody suggested the Edelbrock? i keep one in my shed i fit up to cars that run like bags of ch!t, just to prove it's a carb fault. i bought a strip kit for mine but it just works so well as it came stock. they're almost a T/quad in their design & just like the T/quad, no gaskets below the fuel line.
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/04/10 11:17 AM

Quote:

why hasn't anybody suggested the Edelbrock? i keep one in my shed i fit up to cars that run like bags of ch!t, just to prove it's a carb fault. i bought a strip kit for mine but it just works so well as it came stock. they're almost a T/quad in their design & just like the T/quad, no gaskets below the fuel line.

That's one that I was asking about also in my origional post also, a friend of mine put a Edelbrock on his 340 Cuda and love's it,,,took a little to get it tuned in, but once we hit the sweet spot then
Posted By: BigBlockMopar

Re: best replacement carb for a thermo quad - 07/04/10 12:01 PM



If it sit's more than a week you have to prime the carb with gas to start it, no amount of pumping the accelerator give's it enough gas to start,, act's like the bowl's are completely dry,,,won't go into 4 barrel mode when pedal is slammed to the floor, run's on 2 barrel only,,,idle adjustment screw's have no effect on idle quality,,,and it is just a scuzzy, scurvey, nasty looking mess,,I just want to make sure all is good and ready to go with the best economy that I can get from this barge.




Doesn't sound like 'Thermoquad only' carb-problems to me. More just a neglect of maintainance
The "no-4bbl" mode sounds like a simple linkage adjustment could fix easily, or maybe the sec. airvalve spring is adjusted too tightly. Does the kickdown function OK?
Idle screws, perhaps the fuel passages are blocked with dirt or something, or there's a vacuum problem somewhere.
The 'empty' carb priming is something more cars have and can be fixed by installing a simple fuelpump near the fueltank.
Adding a thicker heat insulating spacer under the carb could help aswell.

If you decide you want another carb, I would personally go with an Edelbrock carb.
Posted By: dOoC

Re: best replacement carb for a thermo quad - 07/04/10 03:57 PM

Mega-DITTOS to SOME of what HermO said .....

'cept that Eddy carb ...

That is a stone-age carb compared to the TQ. You want FUEL ECON ? .... stick with the TQ.

Get an older FACTORY service manual .... good info and tips in there. PLUS ....go to Napa and get a set of brass floats. Those plastic floats(using the alky-blended fuels) ...are NOT the plan.
Posted By: Qbird

Re: best replacement carb for a thermo quad - 07/04/10 05:12 PM

Quote:



If it sit's more than a week you have to prime the carb with gas to start it, no amount of pumping the accelerator give's it enough gas to start,, act's like the bowl's are completely dry,,,won't go into 4 barrel mode when pedal is slammed to the floor, run's on 2 barrel only,,,idle adjustment screw's have no effect on idle quality,,,and it is just a scuzzy, scurvey, nasty looking mess,,I just want to make sure all is good and ready to go with the best economy that I can get from this barge.




Doesn't sound like 'Thermoquad only' carb-problems to me. More just a neglect of maintainance
The "no-4bbl" mode sounds like a simple linkage adjustment could fix easily, or maybe the sec. airvalve spring is adjusted too tightly. Does the kickdown function OK?
Idle screws, perhaps the fuel passages are blocked with dirt or something, or there's a vacuum problem somewhere.
The 'empty' carb priming is something more cars have and can be fixed by installing a simple fuelpump near the fueltank.
Adding a thicker heat insulating spacer under the carb could help aswell.

If you decide you want another carb, I would personally go with an Edelbrock carb.



All of his symptoms, with the exception of no secondary operation, can be traced directly to leaking wells in the bottom of the float bowl. Break out the JB weld an it'll be fine.
Posted By: ScottSmith_Harms

Re: best replacement carb for a thermo quad - 07/04/10 05:16 PM

I agree, the only thing to replace a Thermoquad with is another Thermoquad. Unless you are going to a modern race carb (which is not going to typically offer the best driveability or fuel economy) it's pretty much impossible to beat a properly tuned Thermoquad for all around everything. I also agree, the Carter AVS/Edelbrock carb is a good/simple carb but really doesn't offer the "best" of anything, it's an average middle of the road design. Most people like them because they are very basic and easy to tune and setup.
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/04/10 10:00 PM

Thank's for all the good info guy's,,,look's like I am going to try an attempt at fixing this myself, soon as I get a couple of items fixed first because I will need to start it and move it around once those thing's are done then I will tackle the carb,,,what's the worse that can happen?
Posted By: BigBlockMopar

Re: best replacement carb for a thermo quad - 07/04/10 10:26 PM

Leaky fuel wells would make the engine run rich all the time, and would also cause hard starting everytime you turn off the engine, as some fuel continue to dribble into the manifold. Been there done that.
Of course they could still leak ofcourse, and it would be probably smart to carefully break 'm loose anyway and reglue them again with JB Weld.


Quote:

Mega-DITTOS to SOME of what HermO said .....

'cept that Eddy carb ...



Well, at least we still agree on THIS then I suppose...




Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/04/10 10:35 PM

Any one ever heard of Southern Carb's and rc hobby in Jackson Mississippi?,,,looked up Thermoquad's on E-Bay and they came up as a supplier,,,98% posative feedback. seem's to be reasonable on their pricing for complete rebuild's.
Posted By: Thumperdart

Re: best replacement carb for a thermo quad - 07/04/10 10:38 PM

How much do they want..........I did one years ago and heard it ended up on a bad ass record setting small block I`m just saying.... 1-760-241-1149
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/04/10 10:48 PM

239.00 for the one listed, and a 6 month warranty.I have your # wrote down in my little book of important people to know.
Posted By: Thumperdart

Re: best replacement carb for a thermo quad - 07/04/10 10:52 PM

Quote:

239.00 for the one listed, and a 6 month warranty.I have your # wrote down in my little book of important people to know.

Is that a rebuild or exchange? I can definately beat that price..........And, I can get it back to ya in a couple of days. Oh, I`m not THAT important....
Posted By: Lil Wedge

Re: best replacement carb for a thermo quad - 07/04/10 11:00 PM

Hite rebuilders here in Columbus on Mckinley ave. ,great job have done several for me for my customers on the old church bus Dodge vans
Posted By: dartman366

Re: best replacement carb for a thermo quad - 07/04/10 11:03 PM

Quote:

Quote:

239.00 for the one listed, and a 6 month warranty.I have your # wrote down in my little book of important people to know.

Is that a rebuild or exchange? I can definately beat that price..........And, I can get it back to ya in a couple of days. Oh, I`m not THAT important....

That is a buy now.
Posted By: Thumperdart

Re: best replacement carb for a thermo quad - 07/04/10 11:05 PM

That`s about right I guess.......why buy when yours was working and just needs a freshen and of course a few TWEEKS........your call......good luck.
Posted By: moon

Re: best replacement carb for a thermo quad - 08/03/10 12:16 AM

I have a question about the thermoquad for a 360. im looking to get one but i dont have the original and the person on the phone as if the bowl vent was in the front or rear. I dont which one i need or is better. can anyone help me??
Posted By: dartman366

Re: best replacement carb for a thermo quad - 08/03/10 01:58 AM

might ask this question in the resto section, I am sure those guy's would know, sorry I cant help but here's a for ya any way....oh and by the way the rebuilt thermoquad appears to work great, hope to take her on a short road trip this weekend.
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