Thermo Quad Help!

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swingingdart

swingingdart

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okay, my first start up of my engine, and my thermo quad is leaking from the primary butterfly shafts and from the carb-intake gasket. I have put plugs on some of the out going lines from the base of the carb, which is the fuel return? and or whats the problem? I belive it's a 75' or 74' it's from a 440. (850cfm). thanks guys!!
 
there are bushings there and I have hear of leaking in that area before alot, there are lots of great web sites on rebuilding or working on thermoquads just google it
 
no, no, just when it's off. like I said I do have many holes plugged, I'm going to look again for a chart of what lines go where. but does anyone know right off hand where the fuel return line is?+and do you guys understand why the charcoal canister has a line that is labeled "DIST VAC"?
 
There is no fuel return line. There is a float bowl vent line. Was the carb disassembled?
 
yes, the carb was dissasembled. this isn't supposed to have pressure problems right?. I dunno, I changed everything, gaskets, needles, needle seats, and almost everything but the floats; but the floats were good, I checked them. could I have made some rooky mistake on rebuilding the carb? thanks guys!
 
Thermoquads are more sensitive to fuel pressure than say a Holley for example. They do not need to see much more than about 5 or so PSI. But that pressure needs to be constant. Also, you need to use brass floats. If brass floats were not used, there's a BIG red flag. I don't care if new floats were installed. All that's available for thermoquads are brass or that stupid nytrile foam bullshit. Even new nytrile floats are crappy. They will abdorb some fuel right off the bat, and over time, get worse and worse. Plastic is even better, but no plastic floats are available, so brass it is. Generally, unless the throttle shaft holes and shafts are just wallowed slam the hell out, you will not see fuel coming from there, so my guess is extra fuel is being dumped in....usually from heavy floats or improperly adjusted float level. One last thing.....I always remove a Thermoquad after getting it all tuned and running after a couple of days. The screws holding them together need retightening. You might do that as well.
 
Jet well boots at bottom of phenolic body need to be re-epoxyed. They are leaking.
 
If you do not have any knowledge of Thermoquads, they are very tempermentle, and hard to tune and adjust , i got alot of these carbs and tried for years to make em work .Because when they do work they work well , but you will have all your hair pulled out by that time , I ended up going with a 625 edelbrock electric choke #1406 . two air screws thats it .
 
Be careful when you set the top down. Make sure the floats are set correctly and move freely. Make sure there not upside down or side swapped. Leave the big side port in the upper aluminum part of the carb open, it is a vent that needs to be open.

The one time mention above about cracked or unattached
Jet well boots at bottom of phenolic body
Click to expand...
is a must to look at and kudos's to this reply. Though it may not be the problem,a problem they can be!!!!!!!
 
well, good point man, I don't think I put them in on the wrong side..... but you know what? I think they were like the same float,, like they both had a rounded part on thesame side, and the drivers side seems to be the biggest leak area. But does anybody know where to get brass floats? I am really not liking whoever switched out the original brass floats for these, I mean come on! I put in a newly painted engine just to pour fuel all over it? lol
 
Okay you guys were right, the jet boots were leaking, and also I had to put in some O rings into where the primaries pic up fuel. Both were leaking. but now I have another problem, she'll finally fire up and she'll rev up for a while then die, any reason for this? I mean it even back fires a little,.... is the fuel pooling up in the intake? anyway to fix this?? Thanks guys!
 
She runs, then dies? Lack of fuel is the only thing I can think of carb wise. Dirt/restriction, idle screw needs to be turned in some.
 
I ment to say that I can rev it up and hold it at a high Rpm, then for no reason she'll die. lack of fuel makes sense, but it has fuel when I look in the carb, but it also backfires a little. I've adjusted the distributer till it seems perfect. lol when I adjust the carb it either gets too much, or too little. strange, but I'll try it some more. lol gotta love your mopar!
 
Yup, somehow it's running outta fuel. Did you ever get that pressure guage?
 
10 screws and a bit of linkage and you can remove the top while on the car...
after a while you'll get good at it..

Take the top off and check down in the "wells" where the long jets go..
there should be a small flat sided o-ring(1) in each one.
 
if you move the throttle you should see the squirters spray if you dont no fuel
 
good point guys, yeah lol I figured out the "o" ring problem, but I havent gotten a fuel pressure guage, a regulator yes. lol and I didn't look for fuel, but the primaries seemed to be moist,but this isn't any reason for me to assume it is getting enough. thats guys. anymore info?
 
okay, I'm looking at fuel pressure guage fittings, and they only say their size by "AN" I think, anyway what size is 5/16 in an?
 
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