Previous Thread
Next Thread
Print Thread
Page 1 of 2 1 2
Alternative to Using a ThermoQuad #2659476
05/26/19 09:52 PM
05/26/19 09:52 PM
Joined: Aug 2003
Posts: 2,403
Fargo ND
M
moparphilll Offline OP
top fuel
moparphilll  Offline OP
top fuel
M

Joined: Aug 2003
Posts: 2,403
Fargo ND
The Question:
What are the options OTHER THAN using a ThermoQuad Carb on my 340 to get the SAME height so my Shaker Bubble does not rub on Hood. I used a Base plate under a ederbrock performer carb and it raised the bubble to high. Do the make a replacement carb for the 71 thermoquad?

Last edited by moparphilll; 05/26/19 10:05 PM.
Re: Alternative to Using a ThermoQuad [Re: moparphilll] #2659498
05/26/19 11:00 PM
05/26/19 11:00 PM
Joined: Dec 2007
Posts: 16,341
Mass
DAYCLONA Offline
I Live Here
DAYCLONA  Offline
I Live Here

Joined: Dec 2007
Posts: 16,341
Mass
Originally Posted by moparphilll
The Question:
Do the make a replacement carb for the 71 thermoquad?


Personally I'd make the TQ "work"...but if your seeking a "newer" alternative, there's the Demon

demontq.jpg
Re: Alternative to Using a ThermoQuad [Re: DAYCLONA] #2659506
05/26/19 11:53 PM
05/26/19 11:53 PM
Joined: Mar 2007
Posts: 571
Southeast Pa.
SALEM1912 Offline
mopar
SALEM1912  Offline
mopar

Joined: Mar 2007
Posts: 571
Southeast Pa.
X2 on the TQ find someone to rebuild it.

Re: Alternative to Using a ThermoQuad [Re: moparphilll] #2659508
05/26/19 11:57 PM
05/26/19 11:57 PM
Joined: Jan 2003
Posts: 1,597
s. e. pa.
C
calrobb2000 Offline
pro stock
calrobb2000  Offline
pro stock
C

Joined: Jan 2003
Posts: 1,597
s. e. pa.

holley

there was a holley replacment for the thermoquad they turn up now and then .

think i got one layin around somewhere .

Re: Alternative to Using a ThermoQuad [Re: DAYCLONA] #2659541
05/27/19 08:14 AM
05/27/19 08:14 AM
Joined: Jul 2003
Posts: 3,908
Holland MI Ottawa
2
2boltmain Offline
master
2boltmain  Offline
master
2

Joined: Jul 2003
Posts: 3,908
Holland MI Ottawa
Originally Posted by DAYCLONA
Originally Posted by moparphilll
The Question:
Do the make a replacement carb for the 71 thermoquad?


Personally I'd make the TQ "work"...but if your seeking a "newer" alternative, there's the Demon


Yes this. If the Demon here will work your not only getting a brand new carb but an improved version of the Thermoquad. The Demon incorporates the best attributes of the Thermoquad the Quadrajet and the AFB with some additional improvements. Gentleman who designed it worked for Carter back in the 60s and 70s.


Keep old mopars alive.
Re: Alternative to Using a ThermoQuad [Re: 2boltmain] #2659544
05/27/19 08:22 AM
05/27/19 08:22 AM
Joined: Nov 2003
Posts: 35,231
Lincoln Nebraska
R
RapidRobert Offline
Circle Track
RapidRobert  Offline
Circle Track
R

Joined: Nov 2003
Posts: 35,231
Lincoln Nebraska
^^^ sounds like a good plan assuming the "height" ain't a problem.


live every 24 hour block of time like it's your last day on earth
Re: Alternative to Using a ThermoQuad [Re: RapidRobert] #2659550
05/27/19 09:07 AM
05/27/19 09:07 AM
Joined: Jun 2018
Posts: 160
Mequon, WI
G
gzig5 Offline
member
gzig5  Offline
member
G

Joined: Jun 2018
Posts: 160
Mequon, WI
The main fitment problem I've heard about with the Street Demon carb is that a drop base air cleaner can hit the choke body. Folks either go with a flat lower pan or modify it for clearance.

The Street Demon is supposed to work very well out of the box. I was very close to buying one but fell into a good sale on an Edelbrock AVS2.

Re: Alternative to Using a ThermoQuad [Re: gzig5] #2659580
05/27/19 10:40 AM
05/27/19 10:40 AM
Joined: Sep 2003
Posts: 11,193
north of coder
moparx Offline
Dreaming of implants
moparx  Offline
Dreaming of implants

Joined: Sep 2003
Posts: 11,193
north of coder
if you have the room around the valve covers, "sometimes" a 15 or 16" circle track drop base will work for extra choke clearance.
it may need modification however.
beer

Re: Alternative to Using a ThermoQuad [Re: gzig5] #2659585
05/27/19 10:45 AM
05/27/19 10:45 AM
Joined: May 2019
Posts: 288
nowhere
S
Sniper Offline
enthusiast
Sniper  Offline
enthusiast
S

Joined: May 2019
Posts: 288
nowhere
Dimensions of the Demon Carb, courtesy of Speedway motors.

[Linked Image]

Relevant height: This carburetor is 3 1/4" tall from the bottom of the carburetor to the air cleaner surface., In the Q&A section.

Re: Alternative to Using a ThermoQuad [Re: Sniper] #2659590
05/27/19 10:54 AM
05/27/19 10:54 AM
Joined: Sep 2003
Posts: 11,193
north of coder
moparx Offline
Dreaming of implants
moparx  Offline
Dreaming of implants

Joined: Sep 2003
Posts: 11,193
north of coder
good information to know. thanks for posting that ! up
beer

Re: Alternative to Using a ThermoQuad [Re: moparx] #2659612
05/27/19 12:20 PM
05/27/19 12:20 PM
Joined: Jan 2003
Posts: 13,519
So Near, Yet So Far
topside Offline
I Live Here
topside  Offline
I Live Here

Joined: Jan 2003
Posts: 13,519
So Near, Yet So Far
Best street carb I ever had was a T-quad that Demonsizzler went through for me.
Haven't seen a post from him in years, though.
App was a 406" SB Duster street car with A/C; started quickly after sitting, ran clean, perfect throttle response, 17MPG.
That was 2002-2004.

Worst POS carb I've ever had was a Race Demon 850DP, so I'm leery of the brand even though the one posted is a different animal.

Re: Alternative to Using a ThermoQuad [Re: topside] #2659629
05/27/19 01:24 PM
05/27/19 01:24 PM
Joined: Jul 2008
Posts: 18,996
...to Paradise from ParaICE !
Doc Fiberglass Offline
Help! I've fallen and can't get up!
Doc Fiberglass  Offline
Help! I've fallen and can't get up!

Joined: Jul 2008
Posts: 18,996
...to Paradise from ParaICE !
The Q should be .... why do you feel the Plastic Fantastic should be replaced ?


...... oh I’m UP ... BIG TIME ... alive and well ... the Noble Crusader !
Re: Alternative to Using a ThermoQuad [Re: Doc Fiberglass] #2659765
05/27/19 09:21 PM
05/27/19 09:21 PM
Joined: Jan 2003
Posts: 6,875
Freeport IL USA
P
poorboy Offline
master
poorboy  Offline
master
P

Joined: Jan 2003
Posts: 6,875
Freeport IL USA
I had several different carbs on my 50 Dodge 4x4. It seems even the best one had to be messed with every year (I live where we have cold winters and hot summers, and the truck was driven year around. The best fix I ever made was installing electronic fuel injection.
That truck had the last carb on anything short of the mower at my house. Gene

Re: Alternative to Using a ThermoQuad [Re: moparx] #2659793
05/27/19 11:21 PM
05/27/19 11:21 PM
Joined: Aug 2003
Posts: 2,403
Fargo ND
M
moparphilll Offline OP
top fuel
moparphilll  Offline OP
top fuel
M

Joined: Aug 2003
Posts: 2,403
Fargo ND
shaker base

IMG_6260.JPG
Re: Alternative to Using a ThermoQuad [Re: moparphilll] #2659817
05/28/19 12:51 AM
05/28/19 12:51 AM
Joined: Jan 2003
Posts: 27,234
Balt. Md
3
383man Offline
Too Many Posts
383man  Offline
Too Many Posts
3

Joined: Jan 2003
Posts: 27,234
Balt. Md
Holley did make a replacement carb with small primaries and big secondaries for the Quadrajet which I believe would also work as a Thermoquad replacement. Don't know if its still made though. I also agree the Thermoquad is a good carb if you know what your doing with it as they work great when done right.
I believe Mopar Muscle tested the Demon Thermoquad replacement they make about a year or so ago in the mag and it worked good. I have heard that Demon carb shown in this thread is a good working carb. Ron

Re: Alternative to Using a ThermoQuad [Re: moparphilll] #2659882
05/28/19 09:14 AM
05/28/19 09:14 AM
Joined: Jan 2003
Posts: 5,197
Benton, IL.
D
DaveRS23 Offline
master
DaveRS23  Offline
master
D

Joined: Jan 2003
Posts: 5,197
Benton, IL.
The Thermoquad was a pretty good carb in it's day, but they were not without their problems. And as with any 50 year old carb, they were designed to run on a very different fuel than they would see today. So, any Thermoquad would need a bit of work.

The Street Demon was designed by an former Carter engineer, which is why it is similar to the Thermoquad. But it has a number of design features that set it apart from any other mild street oriented carb out there including the Thermoquad.

Go with the Street Demon. As mentioned, the only issue that might be encountered is the choke housing.


KOS
Re: Alternative to Using a ThermoQuad [Re: DaveRS23] #2660000
05/28/19 01:07 PM
05/28/19 01:07 PM
Joined: Oct 2008
Posts: 757
Seattle, Washington
72roadrunnergtx Offline
super stock
72roadrunnergtx  Offline
super stock

Joined: Oct 2008
Posts: 757
Seattle, Washington
I have some recent experience trying to get a Street Demon 750 to run well on one of my Mopars. The following is my observation/opinions. The motor is a mild build 400, cold Edlebrock performer intake and E-street heads. Out of the box it was jetted pretty close for this combo but accelerator pump didn’t seem to be working correctly. Wound up having to open it up, found small gaps in lip of the acc pump the lip seal and a tear in the Holley umbrella style check valve. After replacing those parts the pump worked better but still needed some larger nozzle tuning to resolve some slight residual hesitation.

No trouble height wise as a Thermoquad replacement but required extensive throttle lever modifications to retain the original throttle cable, throttle pressure linkage components, and correct overall geometry. The Mopar throttle pin adaptor designed for the Street Demon and installed on the “universal” throttle lever on the Street Demon, was useless in avoiding the extensive mods. Plumbing for bowl vent and charcoal canister purge are not present, as with most universal aftermarket carbs.

Could never get the choke tuned correctly for decent cold start & run. The factory dual snorkel air cleaner had no issues with the choke housing. The documentation that came with Street Demon refers to possible interference with the choke linkage near the air horn and factory style air cleaners. There is nothing the locate, or center, the lower air cleaner other than the air cleaner stud. I could see where the air cleaner could shift out of place and contact the linage.

Another irritating issue was the “goggle” valve, secondary throttle blade, binding in its bore requiring excessive throttle pressure to overcome periodically, especially on first use after warm-up. Tried to reseat the throttle blade on its shaft to correct, helped a little but never resolved the issue completely.

Overall tolerances of the various components are not anything close to the Thermoquad, when in good shape, or new Holleys, ended up going back to the best Thermoquad I have. While a bit complex by comparison, with parts that are hard to come by now, a correctly tuned Thermoquad, in good shape, is hard to beat for performance and all-around drivability.

Holley still does make a spread bore replacement but it’s a 650 CFM vacuum secondary GM replacement design with a universal throttle lever. Ran one of those too, good drivability overall, just not same full throttle punch IMHO. The Mopar specific models are now long out of production.

BTW, I have the Street Demon 750 and all the extra tuning parts for it currently are on E-bay should there be someone here who would care to take it on. Priced well below what I have in it.

Street Demon 750

Last edited by 72roadrunnergtx; 05/28/19 08:50 PM.
Re: Alternative to Using a ThermoQuad [Re: moparphilll] #2660269
05/29/19 10:46 AM
05/29/19 10:46 AM
Joined: Nov 2004
Posts: 486
3
340clone Offline
mopar
340clone  Offline
mopar
3

Joined: Nov 2004
Posts: 486
I also have a '71 340 shaker set up. I eliminated the Thermoquad by going with a '70 factory cast iron intake, so I could use an AVS.

Re: Alternative to Using a ThermoQuad [Re: 340clone] #2660278
05/29/19 11:17 AM
05/29/19 11:17 AM
Joined: Oct 2008
Posts: 757
Seattle, Washington
72roadrunnergtx Offline
super stock
72roadrunnergtx  Offline
super stock

Joined: Oct 2008
Posts: 757
Seattle, Washington
Should be noted too that the Street Demon is not really a Thermoquad replacement as it is a square bore configuration. It likely will not bolt directly on an OE cast iron spread bore manifold, just like the Edelbrock carbs, requires the use of a square bore to spread bore adaptor, that would mean additional height.

Last edited by 72roadrunnergtx; 05/29/19 11:30 AM.
Re: Alternative to Using a ThermoQuad [Re: 72roadrunnergtx] #2660293
05/29/19 11:53 AM
05/29/19 11:53 AM
Joined: May 2019
Posts: 288
nowhere
S
Sniper Offline
enthusiast
Sniper  Offline
enthusiast
S

Joined: May 2019
Posts: 288
nowhere
I have run many an Edelbrock carb on a spreadbore manifold with no adapter. Just a thick carb to manifold gasket is sufficient.

Page 1 of 2 1 2

Advertisement
Moparts Newest Topics
Carlisle Photos!
by 68SportFury. 07/19/19 11:26 PM
Aluminum inspection tag orientation 71 Barracuda
by David1971. 07/19/19 10:01 PM
Original RoadRunner A12 hood WIW
by moe318. 07/19/19 09:57 PM
CONSOLE BOX "BUTTON"
by Magnumguy. 07/19/19 09:22 PM
Free standing portable AC unit experience?
by jcc. 07/19/19 05:00 PM
Moparts Recent Posts
Carlisle Photos!
by DirectSubjection. 07/20/19 12:23 AM
1961 Seneca gas tank
by demon. 07/20/19 12:21 AM
Big Block 4wd Bell Housing,
by chrisf. 07/20/19 12:14 AM
Trailer tire advice
by SomeCarGuy. 07/20/19 12:10 AM
Street strip toy!
by Iowan. 07/19/19 11:58 PM
Outrageous $$ At Carlisle
by Dragula. 07/19/19 11:51 PM

Powered by UBB.threads™ PHP Forum Software 7.7.1