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Thermoquad idling extremely rich **UPDATE**
#349418
06/16/09 09:17 PM
06/16/09 09:17 PM
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Slantytown
DUFFMAN
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A week ago I swapped an Edlebrock 1406 for a factor 340 TQ (6139 I think) that I had just rebuilt. It was running great all weekend, then tonight the car started hard and when I did finally get it started it was running so rich it's puffing out black smoke. I took the top of the carb off, check the float height (brass floats), took the needles out inspected them and blew out the seats. I couldn't find anything wrong with it. I put it back together and it's still running rich like before. I'm not sure what to do next. 
Last edited by DUFFMAN; 06/23/09 08:49 PM.
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Re: Thermoquad running rich
[Re: DUFFMAN]
#349419
06/16/09 09:46 PM
06/16/09 09:46 PM
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Slantytown
DUFFMAN
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I'll also mention that I did swap a 14" Edlebrock air cleaner for a factory drop door air cleaner last night. (I noticed it menation as a problem on Demonsizzler's site) but the rich condition continues even with the air cleaner removed.
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Re: Thermoquad running rich
[Re: DUFFMAN]
#349420
06/16/09 09:56 PM
06/16/09 09:56 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Lincoln Nebraska
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Is the metering rod tree being pulled down at idle
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Re: Thermoquad running rich
[Re: DUFFMAN]
#349423
06/17/09 02:45 PM
06/17/09 02:45 PM
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Slantytown
DUFFMAN
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Here's what I'm thinking; the problem didn't start until I swapped air cleaners, so I must have bumped something in the process. The only 3 external things I can think of that would affect fuel metering are;
1. The metering rod tree. Which seems to be moving freely, but I will watch it with the engine running to make sure it pulls down.
2. Divorced choke. I can take measurements to make sure it is still adjusted properly.
3. Choke pull off. I'll hook a vacuum pump to it and make sure it's still working.
Anything else I should check?
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Re: Thermoquad running rich
[Re: 1_WILD_RT]
#349430
06/17/09 07:46 PM
06/17/09 07:46 PM
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Joined: Mar 2005
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Slantytown
DUFFMAN
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I originally used the square o-rings, when I took the top off I replaced them with the "X" style o-rings that Demonsizzler recommends using. No change with either style o-ring.
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Re: Thermoquad running rich
[Re: DUFFMAN]
#349431
06/17/09 08:55 PM
06/17/09 08:55 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
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Dont give up on it yet it's gotta be something simple(it will be when you find it  )especially since it happened suddenly. More thoughts: put the old aircleaner assy back on & see what happens. maybe the underside of the lid on the new one is too close to the vents but I wouldn't think it'd cause that kind of richness. I'm wondering if one of the wells in the phenolic body sprang a(slight) leak and when you had the top off neither of the floats were waterlogged? I would take the whole carb off & go over it w a fine tooth comb. You'll have a good laugh when you spot it.
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Re: Thermoquad idling extremely rich
[Re: DUFFMAN]
#349432
06/17/09 08:59 PM
06/17/09 08:59 PM
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Joined: Jan 2003
Posts: 1,255
Columbus, GA
Michael Ecks
pro stock
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pro stock
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Columbus, GA
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It's been a long time since I have had my hands in one. IIRC on the bottom of the bowl there are two smaller bakelite pieces glued to it to form a kind of V shape in one of the fuel passages. Those are bad to leak over time. When I was working on them we put something like JB Weld around those seams and also put a foam part from a Q-Jet in between the bottom of those V's and the base casting to keep upward pressure on the seam.
If those seams are leaky they would allow fuel to pour into the throttle bores between the bowl and the base casting.
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Re: Thermoquad running rich
[Re: DUFFMAN]
#349435
06/17/09 09:19 PM
06/17/09 09:19 PM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
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Quote:
Quote:
I'm wondering if one of the wells in the phenolic body sprang a(slight) leak and when you had the top off neither of the floats were waterlogged?
Float bowl levels looked normal.
You'd never see a visable flaw in the wells, seperating the body while it still has fuel in it you should see a wet area.. Most experianced TQ guys just epoxy them as SOP...
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Re: Thermoquad idling extremely rich
[Re: astrobuf]
#349437
06/17/09 10:47 PM
06/17/09 10:47 PM
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Slantytown
DUFFMAN
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Well I got the Eddy bolted back up, but I didn't get it back on until after the kids went to bed so I'll have to wait until I get home from work tomorrow to fire it up.
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Re: Thermoquad idling extremely rich
[Re: DUFFMAN]
#349438
06/17/09 11:02 PM
06/17/09 11:02 PM
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Joined: Mar 2008
Posts: 571
Western NC
68Bullit
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Western NC
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Quote:
I'm afraid I've seen this problem with my TQ. The problem turned out to be high fuel pump pressure. I was running at 5-6 psi and this was enough to push the needles off the seats. The problem only occurs when the engines running and the high bowl level ends up spilling fuel from the bleeds into the throttle bores. It makes the car run really rich and unresponsive to idel screw adjustments.
To fix this, I ended up plumbing in a fuel pressure regulator and dropping pressure to 3.5 psi. Problem solved!
I think this would be VERY worth checking out. I talked with DemonSizzler about this very thing and we agreed that it couldn't hurt to add a regulator just to be sure.
My TQ is doing the exact same thing BTW, and I haven't taken anything apart yet. DemonSizzler just sent me this carb and it looks great, and I'm also confident that it has been prepped sufficiently.
Think about this. If you go back to your Eddy carb, and it runs fine, I still wouldn't discount that if your fuel pressure is high, that one carb may do fine (though probably temporarily), while the other one runs overly rich (This case being the TQ) 
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Re: Thermoquad idling extremely rich
[Re: 68Bullit]
#349439
06/17/09 11:11 PM
06/17/09 11:11 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
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It happened all of a sudden which makes me think leaking wells rather than the psi suddenly going higher, if it's not regulated now there is no regulator to fail to let the psi go higher, that & when it happened it also would not start so I dont think excessive psi would come from a fuel pump at cranking speed. . If the wells spring a minute leak it would flood it & make it hard to start & when it does start it'd be way rich as described.
live every 24 hour block of time like it's your last day on earth
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Re: Thermoquad idling extremely rich
[Re: RapidRobert]
#349440
06/18/09 08:45 AM
06/18/09 08:45 AM
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Slantytown
DUFFMAN
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I'm not giving up on the TQ just swapping for the Eddy for right now. First, to make sure that the problem is with the carb and not something else. Second, since the car is my weekend cruiser, and the weekend is almost here, so I want it drivable again.
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Re: Thermoquad idling extremely rich
[Re: boydsdodge]
#349444
06/18/09 07:05 PM
06/18/09 07:05 PM
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Slantytown
DUFFMAN
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It's running great with the Eddy, so there is definetely something wrong with the TQ.
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Re: Thermoquad idling extremely rich
[Re: DUFFMAN]
#349445
06/19/09 07:02 AM
06/19/09 07:02 AM
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Slantytown
DUFFMAN
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Whatever the problem is it requires vacuum. The carb has been sitting on my work bench now for 1.5 days full of gas and hasen't leaked anything.
I still want to find the problem and fix it because I would like the stock appearence and it has better throttle response than the Eddy.
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Re: Thermoquad idling extremely rich
[Re: DUFFMAN]
#349446
06/19/09 07:16 AM
06/19/09 07:16 AM
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Joined: Jan 2003
Posts: 826
Stone Mt, GA.
DEMONSIZZLER
super gas
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super gas
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Stone Mt, GA.
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More than likely, either the needle seat(s) is/are not tight enough in the top and the float bowls are over-filling or a float is defective and taking in gas(only if it feels heavier than it should and you probably already know it is not)or you are missing one or both of the seat gaskets. Float level too high is the last possibility, David.
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Re: Thermoquad idling extremely rich
[Re: DEMONSIZZLER]
#349447
06/19/09 08:50 AM
06/19/09 08:50 AM
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Slantytown
DUFFMAN
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This happened suddenly. So is it possible that that one of the seats loosened up? When this all first started I took the top off, checked the float level and inspected the needles and seats (which are new). I noticed some brass shavings in the bottom of the passenger's side bowl so I cleaned them out. Maybe I have a defective seat?
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Re: Thermoquad idling extremely rich
[Re: DUFFMAN]
#349449
06/23/09 10:01 PM
06/23/09 10:01 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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Quote:
Quote:
More than likely, either the needle seat(s) is/are not tight enough in the top and the float bowls are over-filling or a float is defective and taking in gas(only if it feels heavier than it should and you probably already know it is not)or you are missing one or both of the seat gaskets. Float level too high is the last possibility, David.
Over the weekend I openned the TQ up and noticed brass shavings in the bowl again. So I swapped the needle seats with the old ones and reset the float height.
Tonight I put the TQ back on and it's not running rich anymore, but I still have a problem, I still can't get it to idle below 850 rpm without it dying and after I peg the throttle it settles back down to around 1000 rpm even if I push the throttle closed. I also noticed the choke plate isn't openning fully.
sounds like a vaccuum leak
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