Previous Thread
Next Thread
Print Thread
Page 1 of 2 1 2
ThermoQuad vapor lock, what is it? What are symptoms? #768340
08/08/10 11:51 AM
08/08/10 11:51 AM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
Just had my 800 TQ restored. Runs great around the neighborhood but got back from a 40 mile trip in 85 degree temps. Shifted in 1st & 2nd, no problem but the hotter it got had all kinds of stuttering and bogging and drowneding. Couldn't get any faster than 40-42 mph. I stopped for 10 minutes, it got better for the next mile, barrely got up the hills. Engine temp was fine on the gauge, engine compartment is very hot. Was the gas boiling? Thanks


Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768341
08/08/10 12:30 PM
08/08/10 12:30 PM
Joined: Dec 2004
Posts: 1,061
New Mexico
D
dmerc Offline
super stock
dmerc  Offline
super stock
D

Joined: Dec 2004
Posts: 1,061
New Mexico
Better verify your coolant temp. Thermoquads are the best carb for hot temps because of the plastic center section. Fuel stays a good bit cooler. Sounds like your problem lies elsewhere unless the carb rebuild was goofed up.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768342
08/08/10 03:01 PM
08/08/10 03:01 PM
Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
R
Rug_Trucker Offline
I Live Here
Rug_Trucker  Offline
I Live Here
R

Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN


"The only thing to do for triumph of evil is for good men to do nothing"

"NUNQUAM NON PARATUS!"
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768343
08/08/10 03:22 PM
08/08/10 03:22 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation
NEED more info ......like ...

Is the carb tooo hot to touch ? ... is the intake exh-heat crossover open? .. how hot is that? what is the water temp?

WHO did the restro on the carb?

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: dOrk !] #768344
08/08/10 03:33 PM
08/08/10 03:33 PM
Joined: Jan 2003
Posts: 32,930
Grand Prairie,Texas
stumpy Offline
I Win
stumpy  Offline
I Win

Joined: Jan 2003
Posts: 32,930
Grand Prairie,Texas
I would think vapor lock will be a fuel line heat problem not a carb trouble. Silly question but did you look at the choke to make sure it was wide open?

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: stumpy] #768345
08/08/10 03:39 PM
08/08/10 03:39 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation
Heated fuel line ? ...could be. Something for him to check. ALSO see how hot the fuel pump is. The choke-blade? ... also something to check .. but if it was closed(or close to-it) .. there would be tons of black-smoke.

LEADS to another Q ...what type of choke are you using ?

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: dOrk !] #768346
08/08/10 04:18 PM
08/08/10 04:18 PM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
OK, Scott Smith @ Harms did the resto, he has been a wealth of info. The car doesnot run hot on the temp gauge, heat crossover is open and has burned the newly powder coated intake, stock divorced choke is working and seems to be closing and opening correctly BUT everything is scorching HOT...the air cleaner, all the hoses and gas line. I'll check cooling fluid,again.

6129397-CarbTQpic.jpg (89 downloads)

Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768347
08/08/10 04:25 PM
08/08/10 04:25 PM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
2


Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768348
08/08/10 05:55 PM
08/08/10 05:55 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation
Quote:



BUT everything is scorching HOT...the air cleaner, all the hoses and gas line. I'll check cooling fluid,again.




SS knows his stuff so that is not the problem. But scorching HOT is. What is that all about? ... tight motor?

The temp guage shows OK ? .. maybe that is way-off.

What type of gasket do you have separating the carb and intake?

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768349
08/08/10 07:02 PM
08/08/10 07:02 PM
Joined: Jan 2003
Posts: 16,818
Between Houston & Galveston TX
SattyNoCar Offline
Smarter than no class Flappergass by a mile
SattyNoCar  Offline
Smarter than no class Flappergass by a mile

Joined: Jan 2003
Posts: 16,818
Between Houston & Galveston TX
Quote:

2




Trying to not go off on a rant here. Trying REAL hard.

Look at this pic, you've got the fuel line coming up between two heat sources going to a METAL fuel filter which is basically acting like a HUGE heat soak, and , you say its gotta be the thermoquad.



Nothing really wrong with the fuel filter, except it should be down close to the fuel pump. The factory ran fuel lines near heat sources, but, todays gas boils at a lower temp. What worked then, doesn't work now. At the very least, you need to reroute and insulate the fuel line to the carb. In an extreme case, you may need to rig up a later 'three prong' fuel filter to vent off the vapors. This is what I had to do with my wagon.


John

The dream is dead, long live the dream.......😥
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: SattyNoCar] #768350
08/08/10 07:09 PM
08/08/10 07:09 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation
ONE HUNDRED and THREE degrees in TX ? ....DAMN.

It is a nice 84 here

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: dOrk !] #768351
08/08/10 07:18 PM
08/08/10 07:18 PM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
Those are the factory stock TQ fuel lines. That pic doesn't show the vac advance hose which is now conected. Has nothing to do with my issue. Before the TQ I had a 670 Holley and never had any hot issues.


Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: dOrk !] #768352
08/08/10 07:21 PM
08/08/10 07:21 PM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
Regarding gaskets. Ihave a thin cork gasket above and below a wood fibre type 1/2" thick spacer.


Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768353
08/08/10 07:41 PM
08/08/10 07:41 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation


You might have a vacuum leak making it go lean ...and then really HOT. OR ... the carb itself is lean.

How do the plugs look? ...

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: dOrk !] #768354
08/08/10 10:19 PM
08/08/10 10:19 PM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
I'm do for plugs. Should I go a couple of levels colder? If the engine just wants to be hot, should the colder plugs help?


Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768355
08/08/10 10:22 PM
08/08/10 10:22 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation
How do the plugs "read" ? .... 1 or 2 steps colder would not hurt.

I would look more-for a vac-leak though.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: dOrk !] #768356
08/08/10 11:08 PM
08/08/10 11:08 PM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
Vacuum Leaks...effin things. A so-called friend took a can of carb cleaner or brake clean and sprayed it at my newly resto TQ ! Now the phenolic is fogged.


Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768357
08/09/10 08:56 AM
08/09/10 08:56 AM
Joined: Apr 2003
Posts: 1,286
Ft. Lauderdale, FL
solarguy Offline
pro stock
solarguy  Offline
pro stock

Joined: Apr 2003
Posts: 1,286
Ft. Lauderdale, FL
I think you need to get your underhood temps in check. Your other posts regarding heat problems are probably related to this problem. Get that motor and the engine compartment as cool as you can first then see where you're at.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: solarguy] #768358
08/09/10 02:52 PM
08/09/10 02:52 PM
Joined: Apr 2010
Posts: 1,216
Under My Car
Mopar_Country Offline
pro stock
Mopar_Country  Offline
pro stock

Joined: Apr 2010
Posts: 1,216
Under My Car
Quote:

Before the TQ I had a 670 Holley and never had any hot issues.




I would assume carb if you had no previous issues. Have you tuned the carb to the engine? If not start there, you may have a lean condition. Are there any other symptoms such as stumbling on take off? TQ's are tricky to tune but I like mine.

Last edited by Mopar Country; 08/09/10 05:02 PM.
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: Mopar_Country] #768359
08/09/10 10:53 PM
08/09/10 10:53 PM
Joined: Aug 2005
Posts: 1,043
Motown, Mi
P
PAULS_340 Offline OP
super stock
PAULS_340  Offline OP
super stock
P

Joined: Aug 2005
Posts: 1,043
Motown, Mi
I think we got the carb tuned to the engine, one more tweak to the secondaries. No stumbling until the engine got real hot. I want it to look pure stock but i'm going to reroute the fuel filter away from the heater hoses.


Still looking for LM29H1B415501, '71 Demon 340
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768360
08/10/10 12:34 PM
08/10/10 12:34 PM
Joined: Apr 2010
Posts: 1,216
Under My Car
Mopar_Country Offline
pro stock
Mopar_Country  Offline
pro stock

Joined: Apr 2010
Posts: 1,216
Under My Car
Put the filter just off the pump and run a new line up to carb. If this is where it was with the other carb how is it going to help by moving it? Just a thought.

I am inclined to think your running lean.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: Mopar_Country] #768361
08/10/10 12:55 PM
08/10/10 12:55 PM
Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
R
Rug_Trucker Offline
I Live Here
Rug_Trucker  Offline
I Live Here
R

Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
Quote:


I am inclined to think your running lean.




Especially if you have the stock jetting and gasahol. You need to jet up 10% or more. Well in the case of a TQ richer rods.


"The only thing to do for triumph of evil is for good men to do nothing"

"NUNQUAM NON PARATUS!"
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: Rug_Trucker] #768362
08/10/10 01:00 PM
08/10/10 01:00 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation
Hay Paul ......

HOW MANY people have to tell-you .....you are probably running WAAAY lean !!

Take it out again ...and CHECK THE PLUGS.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: PAULS_340] #768363
08/10/10 03:58 PM
08/10/10 03:58 PM
Joined: Mar 2007
Posts: 550
ne
B
broncobra Offline
mopar
broncobra  Offline
mopar
B

Joined: Mar 2007
Posts: 550
ne
You can use a hand held propane torch, with the flame turned off, just a light breeze of propane to prevent that when you detect leaks.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: broncobra] #768364
08/10/10 09:33 PM
08/10/10 09:33 PM
Joined: Jul 2003
Posts: 6,167
Maryland
GO_Fish Offline
master
GO_Fish  Offline
master

Joined: Jul 2003
Posts: 6,167
Maryland
Or even a spray bottle of water. That should create a stumble in rpm's instead of an increase in rpm's when you found the leak?

Yes, I think it is vapor lock, and yes, I'm having identical problems with my 360 and AVS. The puller mechanical fuel pump is made to pump liquid, it cannot pump vapor. So yes, high temps anywhere along the fuel line can be heating the E10 gas to the boiling point, and then you're stuck until things cool down. I have tried insulating my fuel line under hood without significant improvement. A very good point was made about the metal fuel filter attracting heat. They used to make a plastic filter with the same dimensions. I may try and find one of those and paint it silver??? My best solution may be to swap my stock 22" 3 core radiator with a new 22 or 26" 4 row core when I can get some money together.

Last edited by GO_Fish; 08/10/10 09:45 PM.

Scott B. "I'm a self-made man... I started with nothing, and I still have most of it!" 68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph 69 340 GTS stock 14.18@ 95.60 mph 01 5.9L Ram 1500 Quad Cab 4x4 01 3.5L 300M 16.23@ 86.97 mph
Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: GO_Fish] #768365
08/11/10 04:32 PM
08/11/10 04:32 PM
Joined: Jan 2003
Posts: 2,931
P
Paul_Fancsali Offline
master
Paul_Fancsali  Offline
master
P

Joined: Jan 2003
Posts: 2,931
The only way I could run a Carter on hot day at the track was with electric pump and cool can and ice. Try blocking the heat passage that will help and a electric pump will also help. I would place the Holley back on and run it screw the factory look when you are involved in wreck due to carb vapor lock its not worth it. I'm now running a 195 stat on 93 degree days and not having any problems at all with my 340 with a Holley and a spacer and todays crap gas

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: Paul_Fancsali] #768366
08/11/10 04:58 PM
08/11/10 04:58 PM
Joined: Jan 2008
Posts: 3,886
Lost and Spaced
B
bboogieart Offline
master
bboogieart  Offline
master
B

Joined: Jan 2008
Posts: 3,886
Lost and Spaced
try a glass see through type filter to see if fuel is boiling off or getting to the carb. This will close in on where your problem is. You will then know what the lean condition is related too. Can easily be put back to stock appearing once the problem is fixed.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: bboogieart] #768367
08/11/10 05:32 PM
08/11/10 05:32 PM
Joined: Apr 2010
Posts: 1,216
Under My Car
Mopar_Country Offline
pro stock
Mopar_Country  Offline
pro stock

Joined: Apr 2010
Posts: 1,216
Under My Car
If all that was changed was the carb, I say it's lean. Lean condition WILL make your engine hot.

1. Take a propane torch, unlit, and check for vacuum leaks, leaks can cause a lean condition. Once you are satisfied there are no leaks I would look at the carb.

2. After the carb was rebuilt it was probably set to factory specs, which is a baseline, it still has to be tuned to the engine. You have to adjust the metering tree UP to richen it. There is a screw down in the little hole above the metering tree. It requires a small screwdriver to access. It could be you need to adjust your accelerator pump as well.

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: Mopar_Country] #768368
08/11/10 05:42 PM
08/11/10 05:42 PM
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOrk ! Offline
The village idiot's idiot
dOrk !  Offline
The village idiot's idiot

Joined: Jul 2008
Posts: 30,424
Florida STAYcation
Hay M C ...

EXSIST ....or EXIST ?

Re: ThermoQuad vapor lock, what is it? What are symptoms? [Re: dOrk !] #768369
08/11/10 05:45 PM
08/11/10 05:45 PM
Joined: Apr 2010
Posts: 1,216
Under My Car
Mopar_Country Offline
pro stock
Mopar_Country  Offline
pro stock

Joined: Apr 2010
Posts: 1,216
Under My Car
oops!

Page 1 of 2 1 2






Powered by UBB.threads™ PHP Forum Software 7.7.1