Thermoquad fuel leak

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Dartfreak75

Dartfreak75

Restore it, Dont part it!
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I was messing around with my dart today and noticed I have a fuel leak on the carb. Its leaking from around the shaft. There is also alot of movement in the shaft I don't think that much is normal.
 
Its a fresh rebuild its only been on the car for a few months. I guess I will pull it off and look at it. I can tell a noticeable difference when I wiggle it while running like I did in the video the idle changes.
 
I had one of those leaked raw fuel into the manifold, I went with a Holley, then an Edelbrock...
 
WOODRUFFCARBURETOR.jpg
 
The fuel leak isn't that big a deal except for the mess is makes. The main thing is that it sucks air through the loose shaft/bushing and that makes the car run poorly!!!
 
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Send me some detailed pics in good light , I probably have one, you can have it for postage.Make sure I can see the carb number
 
The throttle shaft does not intersect fuel, anywhere. If it's leaking fuel from the worn shaft, you have two problems. New gaskets seem to "wick" fuel instead of containing it. Would usually see that on the outside around the airhorn/top. How was the glue on the bottom of the plastic, holding the pods?
 
Yup. Needs throttle shaft bushings. That's wore slap out.
 
I've heard of that being a problem but I've run five different Thermo quads and never had a leaky shaft bushing knock on wood bummer!
 
When the car is not running and fuel is squirted on the shaft it will find its way out. On a running motor the problem is almost non existent. I rebuilt that carb for him last year. I must have judged that shaft to be ok. The TQ has a lot of shaft hanging out there unsupported, so any wiggle is drastically exaggerated out at the end. Unlike a Holley. However had I heard from him about this issue, I would have resolved it. And still will, gladly. But i don’t think that it is sucking much air, last week the OP posted a concern of a possible rich condition. Then that thread just died.
 
I see several questionable things:
1) somebody has tanked and/or bead blasted all the plating off of the linkage. This makes me wonder if the green Teflon coating on the throttle shafts is gone, too.
2) You have double return springs on the throttle shaft linkage, which in and of itself isn't necessarily bad, but maybe the springs are too strong, and putting extra load on the "journal". Also, I suggest you anchor the end of the spring(s) on the throttle stud at the of the cable end shackle(between the "ears"), which lessens the constant torque on the linkage and throttle shaft journal.
I agree with comment about the glue sealing the constant feed well caps on the bottom of the bowl. The glue can be damaged by soaking in carb cleaner. You should never soak the bowls in carb cleaner. Just rinse them in a mild solvent, maybe scrub them a little with a soft toothbrush.
 
Dana said:
When the car is not running and fuel is squirted on the shaft it will find its way out. On a running motor the problem is almost non existent. I rebuilt that carb for him last year. I must have judged that shaft to be ok. The TQ has a lot of shaft hanging out there unsupported, so any wiggle is drastically exaggerated out at the end. Unlike a Holley. However had I heard from him about this issue, I would have resolved it. And still will, gladly. But i don’t think that it is sucking much air, last week the OP posted a concern of a possible rich condition. Then that thread just died.
Click to expand...

Well, I've said as much myself in other posts regarding shaft wear. ....or more appropriately, shaft BORE wear. The incoming air fuel charge will take the path of least resistance and that sure as heck AIN'T through the throttle shaft bores. lol
 
rustycowll69 said:
I see several questionable things:
1) somebody has tanked and/or bead blasted all the plating off of the linkage. This makes me wonder if the green Teflon coating on the throttle shafts is gone, too.
2) You have double return springs on the throttle shaft linkage, which in and of itself isn't necessarily bad, but maybe the springs are too strong, and putting extra load on the "journal". Also, I suggest you anchor the end of the spring(s) on the throttle stud at the of the cable end shackle(between the "ears"), which lessens the constant torque on the linkage and throttle shaft journal.
I agree with comment about the glue sealing the constant feed well caps on the bottom of the bowl. The glue can be damaged by soaking in carb cleaner. You should never soak the bowls in carb cleaner. Just rinse them in a mild solvent, maybe scrub them a little with a soft toothbrush.
Click to expand...
I don't have a double return spring to the throttle I have one on the throttle and one on the kickdown linkage. The one on the kickdown isn't attached to the carb in any way .
 
Dana said:
When the car is not running and fuel is squirted on the shaft it will find its way out. On a running motor the problem is almost non existent. I rebuilt that carb for him last year. I must have judged that shaft to be ok. The TQ has a lot of shaft hanging out there unsupported, so any wiggle is drastically exaggerated out at the end. Unlike a Holley. However had I heard from him about this issue, I would have resolved it. And still will, gladly. But i don’t think that it is sucking much air, last week the OP posted a concern of a possible rich condition. Then that thread just died.
Click to expand...
Yea the rich thread didn't go far it was kinda chalked up to weak spark which lead me to find this today. I was checking my spark and it seemed good to me. Then I noticed a pool of liquid on the intake and I smelt it and it was gas which lead me to messing around with the shaft and I saw that leak. That's when I noticed there was so much play in the shaft. We will get it sorted out tho no worries here. Thanks for posting here I wasn't even gonna mention it because I didn't want you to think I was unhappy with the job you did. I think you did an amazing job and it really runs great I just didn't know if that much play was normal.
 
In my experience, even on a stock smogger teen;
air leaking thru throttle-shaft bushings,
has never been an issue to me,on any carb;
even my 50 year old original-bushings TQ.
Well; with the possible exception of the carb on my ancient worn-out super low compression, early 80s LawnBoy lawnmower, which I finally retired several years ago...... but still have. It got a lil hard for my wife to pull-start.

Your results may vary.

Here's how you can tell if yours has a problem;
Set the transfer slot exposure underneath the throttle blades to a lil taller than wide. Close up the secondaries tight but not sticking. Reset the mixture screws to 2.5Turns from lightly seated. Make sure your float level is set right and pressure test the float valves. And prove the mainwells are NOT leaking . Install a new, correctly calibrated PCV valve.
Install the carb, start and warm up the engine. Then set the Idle-Timing to in the range of 8 to 14 degrees.
Now; what is your idle speed?
Depending on your cam, and it's install, it should be between 650 in neutral to not more than 800/850.
If it is more than 850@12degrees, then the engine is getting unregulated air from somewhere, not necessarily from the bushings. Search it out.
In your searching, you can spray chemicals onto the bushings to see how it affects the idle speed. Do not spray gasoline! I have used water, brakleen, propane, and CO2. Brakleen is cool cuz when it come out the tailpipe, it is highly irritating to your nose. Water will turn to steam. Only pay attention to the change in idle speed. I doubt your engine will even notice propane.
Now, if the bushing slop affects where your idle speed returns to, as in not the same every time, first make sure the the Transfer slot is adequately positioned. If you have set the Idle-Timing to some large number like 18 or 20 degrees, then your throttles will be very near to shutting off the transfers, and your Mixture screws will be doing all the work. So if the throttle does not return to the same place everytime, now you can blame the bushings. But after you install the new bushings, you will find that, if you have not backed off the timing, you are STILL gonna have problems with both the idle-quality, and the tip-in hesitations. So the take-away here is to be sure your transfer slots are contributing adequate fuel. Do NOT try to idle on the mixture screws; they need to be in the sweetspot of adjustability near 2.0 to 2.5 turns.
But everything depends on the correct wet fuel level; get that wrong and suddenly the carb gets a bad reputation. Get it right, and you will think you are driving an injected car.
Happy HotRodding
 
AJ/FormS said:
Ok smarty pants let me rephrase
even my 50 year old original unbushed base TQ.
Click to expand...

Who was bein smart? I'm guessing for all your fancy talk, you've never even held a TQ in your hand.
 
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