Moparts Tech Archive
Fuel System
Thermo-Quad Carb
Adam Batterson
Moparts Member
Posts: 778
From: Northeast Iowa
Registered: Dec 1999
posted 05-23-2002 04:55 PM
I have a TQ on my 360 1 Ton CrewCab, It pulls a 9% grade w/4.10 started a 55 and stepped into a little, 70+ have problems if I try hot starting it, and if mash it to the floor, it pops, and pops, otherwise runs like a dream. Any thoughts on the hot start problem, is the air valve a problem when I mash it to the floor.
AB
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69Dartman
Moparts Member
Posts: 1039
From: Portland Oregon
Registered: Apr 2000
posted 05-23-2002 10:44 PM
If you have the carb bolted straight to the manifold with a regular thin gasket it can get heat soak real bad and cause that. your sposed to use the Thick gasket for heat dissipation. Also if the vent tube doesn't open properly, to early or late it can have problems too. If your getting the popping when you hammer it and the secondaries start to come in it's probably set too lean and you might want to try loosening the adjustment a tiny bit till it clears up. Ohterwise it might be the metering rods being a bit lean on cruise if it just hesitates as you tip it in.
Could be other stuff too but those 2 are pretty good bets.
Also make sure it's still bolted tight to the intake, mine has worked to finger tight before and that cause all kinds of problems that act like some of whats happening to you.
Demon Sizzler Is the TQ man around here if none of this helps.
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Adam Batterson
Moparts Member
Posts: 778
From: Northeast Iowa
Registered: Dec 1999
posted 05-26-2002 04:28 PM
Are the two screws w/ springs, one on each side of the hose that goes the the PCV valve. Give them a couple of turn and see what I got?
Thanks,
AB
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69Dartman
Moparts Member
Posts: 1039
From: Portland Oregon
Registered: Apr 2000
posted 05-26-2002 05:11 PM
those are the idle mixture screws on the front low that you are describing. Turn out to go richer, in to go leaner.
The metering rod tree is that little golden T thing on the top middle of the carb.
The adjustment for the air door is on the linkage side on the top just past the middle of the thing. It has a outer small lock ring and a inner screw slot. you loosen the outer with the special tool. or a BIG screw driver, then adjust the inner sloted thing. Tighter makes it come open later(leaner) looser it opens sooner (richer)
The metering rod tree is adjusted by the little threaded rod with the slot in top, higher is richer, lower is leaner. If you do try to adjust it be carefull because if you go to far it can hang up internaly and stick wide open, so check it first before you go out and have a bad day.
There have been several threads lately on how to adjust the tree and what to look out for. Do a search and you should still be able to find them.
The tech section also has a nice TQ guide by Vaanth that has numbers and some basic info that might be helpful to you.
bugsydog
Moparts Member
Posts: 197
From: las vegas nevada
Registered: Apr 2001
posted 05-22-2002 09:42 PM
I just put my rebuilt thermo on my 72 charger,the motor is stock.I turned the screws out 2 turns a cranked it over. The car runs with no problems except when you try to give it gas it hesitates and even pops through the carb at times.I know it's got to be easy,but i just don't khow what it is. Any ideas?
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440trk
Moparts Member
Posts: 1792
From: Harrisburg,Pa. USA
Registered: Nov 1999
posted 05-22-2002 10:09 PM
Sounds like an accelerator pump adjustment may be needed. I am assuming that you bought a rebuild kit that has instructions...look for the proper settings for the accelerator pump and check there first. If all is well with the pump, post back and we'll take it from there
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Satilite73
Moparts Member
Posts: 3184
From: Somewhere between Houston & Galveston, TX
Registered: Nov 1999
posted 05-22-2002 10:35 PM
Did you reset the metering rods? I've found that a 'pop' when cold is the mixture screws and a 'pop' when warm is the metering rods. Bad pump shot usually causes a stumble or bog.
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Moparts Member
Posts: 197
From: las vegas nevada
Registered: Apr 2001
posted 05-22-2002 10:43 PM
I checked the accelerator pump adjustment and it was right,I don't know about the metering rods due to the fact i didn't rebuild the carb a buddy did and it can't reach him, so i'm doing this without knowing what i'm doing.
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Satilite73
Moparts Member
Posts: 3184
From: Somewhere between Houston & Galveston, TX
Registered: Nov 1999
posted 05-22-2002 10:56 PM
Most rebuild kits available today don't mention how to adjust the metering rods, this is off of a set of directions from about 12yrs ago:
If you do this adjustment, you have to be CERTAIN to notice the MOMENT it starts to move. A well placed mirror works better than feel. Its really not difficult to do. Just remember, counterclockwise = leaner, clockwise = richer
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JonC
Moparts Member
Posts: 147
From: Millinocket, Maine, usa
Registered: Feb 2001
posted 05-22-2002 11:05 PM
Check the dashpot, or whatever it is called. Had a big bog when mashing it for two years untill I discovered it. If the vacuum diaphram is shot the secondary air valve opens too soon and result is BIG TIME BOG and sometimes backfire. Take the small rubber tube off the dashpot and suck on it, if it does not move it, it is bad. Good luck.
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bugsydog
Moparts Member
Posts: 197
From: las vegas nevada
Registered: Apr 2001
posted 05-22-2002 11:59 PM
You guys are the greatest, i'll see if that's the problem and get back with you guys tomorrow.
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Rug_Trucker
Moparts Member
Posts: 1961
From: Near Nashville, TN USA
Registered: Aug 2000
posted 05-23-2002 03:11 PM
How about a vacuum leak? Check around your primary throttle shaft on the passenger side, is it loose?? Mine is! I have 19 to 20 inches of vacuum at idle, but hou can wiglle it and change the idle.
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JonC
Moparts Member
Posts: 147
From: Millinocket, Maine, usa
Registered: Feb 2001
posted 05-23-2002 09:45 PM
Also, when checking the dashpot, when sucking on it, it must hold. I know this sounds pornografic, but suck on it and then put tounge on end of tube to block it. It should hold it and not leak back. If it does leak back, it is history and probably your problem. Good luck!!
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waginator
Moparts Member
Posts: 132
From: Atlanta
Registered: Apr 2002
posted 05-23-2002 10:57 PM
Um, John
Ya don't have to actually put yer mouth on the dashpot/choke pulloff. All you have to do is take off the vaccum hose and an push the plunger in, then put yer finger over the hole on the other side. Then let go of the plunger. If it doesnt hold, bad choke pulloff.
I just did this with the choke pulloff on the Holley 4160 on my 72 NY.
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Lil Red
New Member
Posts: 3
From: Canada
Registered: Mar 2002
posted 05-25-2002 10:46 PM
Thanks Satilite73, I have asked and asked everyone I know on how to adjust the metering rods and you came through for me!!
I can't tell you how much I appreciate it. I have looked in every book, asked in every group without any luck.
My L'il Red needs some carburateur work and this is all I was waiting for.
Thanks once again.
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Satilite73
Moparts Member
Posts: 3184
From: Somewhere between Houston & Galveston, TX
Registered: Nov 1999
posted 05-25-2002 11:04 PM
COOL!! Glad I was able to help ya' Lil Red!
Its such a (relativly) easy adjustment, I don't understand why its been omitted from most rebuild kits nowadays.
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