Thermoquad primary shaft leak

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dartfreak75

dartfreak75

Restore it, Dont part it!
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I found a leak in my primary shaft a while back on my thermoquad its got quite a but of play in it but I been running it anyway. I haven't ran the car much since its got cold but the other day I started it and noticed I have have a really bad vacuum leak I couldn't pin it down exactly where it is at but when I wiggle the wobbly shaft it goes away is it possible to have a vacuum leak around the shaft? Its leaking fuel so I know the bushings are bad but would i be leaking vacuum too? Thanks
 
'It goes away'. What goes away?

Moving a worn shaft in a throttle bore is also going to change the throttle blade position in the bore. At idle when the gap is minute, very small changes here might change the idle speed or idle quality.

A fuel leak might be due to something other than the shaft worn. Even brand new, the shaft has clearance & fuel can leak out.
 
Bewy said:
'It goes away'. What goes away?

Moving a worn shaft in a throttle bore is also going to change the throttle blade position in the bore. At idle when the gap is minute, very small changes here might change the idle speed or idle quality.

A fuel leak might be due to something other than the shaft worn. Even brand new, the shaft has clearance & fuel can leak out.
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The vacuum leak noise.
 
Oh, ok. Must be a sizeable leak/clearance for that much noise. Get it bushed first & proceed from there.
 
Bewy said:
Oh, ok. Must be a sizeable leak/clearance for that much noise. Get it bushed first & proceed from there.
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Im not sure if thats where the vacuum is leaking from thats what I'm asking. I do know when I wobble the shaft the idle changes. The vacuum leak noise could be changing because of that. Im not sure if should fix the carb or look elsewhere for the vacuum leak. Like I said I can't pinpoint it
 
The fact that the idle changes means that the shaft/housing is worn pretty badly & that needs to be fixed.
 
Probably easier to find another base [ or carb ] & use the good base with your float bowl & air horn.
 
Bewy said:
The fact that the idle changes means that the shaft/housing is worn pretty badly & that needs to be fixed.
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Yea I know it does i been meaning to pull it off for a while but just haven't gotten around to it. Im actually considering buying a new carb i love the look of the thermoquad tho.
 
Bewy said:
Probably easier to find another base [ or carb ] & use the good base with your float bowl & air horn.
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I have a couple extra thermoquads laying around for cores i don't know what im gonna do yet. I been considering a new street demon.
 
I thought you had that one professionally built? But yeah, if the throttle shafts are bad enough, it can do that. They have to be really bad though, because air takes the path of least resistance. Those big holes the throttle blades open up are normally the least resistance, so if it's got a vacuum leak around the throttle shaft, it's gotta be BAD.
 
Throttle shaft needs to be repaired either way, so I would bush or replace 1st then go from there.
I had a machine shop do mine 8 or 9 years ago for $30.
 
Messed with some today and found out it's alot more that the shaft thats leaking the top and bottom body seals are leaking also. I made a video I will post as soon as it finishes uploading here are some pics for the time being. Im either gonna pull it off and have it rebuilt again or pull it off and buy a street demon.

20220122_151034.jpg


20220122_151126.jpg


20220122_151137.jpg
 
First off, I told you on May 6 I would have a look at it.
Secondly if the fuel is soaking both gaskets then the needle and seat is not shutting. Heavy float or some debris in it. It has fuel dripping after shut down gauranteed. That is why it is coming out around the throttle shaft.
Instead of making you tube videos, take it off and let’s get to the bottom of it like we discussed 8 months ago.
1A0049D3-0119-4F20-AB27-39EE592F7FFF.png
 
Dana said:
First off, I told you on May 6 I would have a look at it.
Secondly if the fuel is soaking both gaskets then the needle and seat is not shutting. Heavy float or some debris in it. It has fuel dripping after shut down gauranteed. That is why it is coming out around the throttle shaft.
Instead of making you tube videos, take it off and let’s get to the bottom of it like we discussed 8 months ago.View attachment 1715857382
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Pming you.
 
Freak,
You have the BEST carb now. I would NOT use a street demon. I have installed two of them. They are cheaply made, nothing like the Carter quality. One worked ok [ on a Chebby ], the other on a 400 Pontiac ALWAYS had a flat spot that no amount of tuning could fix. The owner actually phoned Holley tech from Australia for help. About as useful as a sun roof on a submarine...
After reading through his computer scroll, the tech had no more ideas...or help. Pontiac owner ended up refitting his QJ, which is still there many years later.
I also recall that to change met rods on the SD risked dropping a circlip into the throttle bore...Not a good design.

Back to the TQ. Just get a gasket/overhaul kit. The pods under the pri main jets might be leaking. Very easy to fix, have done heaps of them. Scrape away the old epoxy & dig a slight channel [ with tip of a knife ] into the joint; re-epoxy with fuel proof epoxy.
You can re-use your centre section & airhorn, just replace the worn base. There is no jetting/metering in the base except for some models that have bypass air holes in the primaries. This is also not a problem. If there are holes in your old base & they are bigger, simply enlarge the holes in the new base.
If the new base has bigger holes, do this: enlarge the existing holes to the next drill size, but do not drill right through. Measure the hole depth; cut off the drill bit shank a little shorter & drop this in the hole. Peen the alum over so that is locked in place. Drill new, smaller holes, next to the old holes if bypass air is reqd. Another thing you can is drill bypass holes in the secondary blades if more convenient.
 
Bewy said:
Freak,
You have the BEST carb now. I would NOT use a street demon. I have installed two of them. They are cheaply made, nothing like the Carter quality. One worked ok [ on a Chebby ], the other on a 400 Pontiac ALWAYS had a flat spot that no amount of tuning could fix. The owner actually phoned Holley tech from Australia for help. About as useful as a sun roof on a submarine...
After reading through his computer scroll, the tech had no more ideas...or help. Pontiac owner ended up refitting his QJ, which is still there many years later.
I also recall that to change met rods on the SD risked dropping a circlip into the throttle bore...Not a good design.

Back to the TQ. Just get a gasket/overhaul kit. The pods under the pri main jets might be leaking. Very easy to fix, have done heaps of them. Scrape away the old epoxy & dig a slight channel [ with tip of a knife ] into the joint; re-epoxy with fuel proof epoxy.
You can re-use your centre section & airhorn, just replace the worn base. There is no jetting/metering in the base except for some models that have bypass air holes in the primaries. This is also not a problem. If there are holes in your old base & they are bigger, simply enlarge the holes in the new base.
If the new base has bigger holes, do this: enlarge the existing holes to the next drill size, but do not drill right through. Measure the hole depth; cut off the drill bit shank a little shorter & drop this in the hole. Peen the alum over so that is locked in place. Drill new, smaller holes, next to the old holes if bypass air is reqd. Another thing you can is drill bypass holes in the secondary blades if more convenient.
Click to expand...
Dana's gonna take care of it for me im mailing it to him tomorrow. Well Monday but tomorrow now lol
 
Kevin, looks like your picking up some rust from the fuel system. It only takes a spec to hold the needle off the seat. Your floats weight out fine. I’ll give it a good cleaning and bush this throttle shaft. Better do some flushing on the fuel system while I have your carb. There can’t be much run time on this carb, so it is pumping rust pretty significantly.
image.jpg
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Oh my, that will cause some problems. Might be time to replace the fuel tank.
 
dartfreak75 said:
Dana's gonna take care of it for me im mailing it to him tomorrow. Well Monday but tomorrow now lol
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Dana has a good reputation. I have not used his services but would use him in a heartbeat. My dad is the one who has always worked on mine. However, he is now retired and not very interested in working on cars anymore.
 
Dana said:
Kevin, looks like your picking up some rust from the fuel system. It only takes a spec to hold the needle off the seat. Your floats weight out fine. I’ll give it a good cleaning and bush this throttle shaft. Better do some flushing on the fuel system while I have your carb. There can’t be much run time on this carb, so it is pumping rust pretty significantly.View attachment 1715864253View attachment 1715864254
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Oh my! Thats bad! Thank you. I cleaned out the tank I guess it didn't help. Iooks like ill be replacing the tank and filters! Thanks Dana I appreciate it.
 
QuickDart360 said:
Dana has a good reputation. I have not used his services but would use him in a heartbeat. My dad is the one who has always worked on mine. However, he is now retired and not very interested in working on cars anymore.
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Dana is the best! He did a fantastic job on that carb you should have seen it before. I never doubted his ability or thought my issues was anything that he did wrong.
 
Dana said:
Kevin, looks like your picking up some rust from the fuel system. It only takes a spec to hold the needle off the seat. Your floats weight out fine. I’ll give it a good cleaning and bush this throttle shaft. Better do some flushing on the fuel system while I have your carb. There can’t be much run time on this carb, so it is pumping rust pretty significantly.View attachment 1715864253View attachment 1715864254
Click to expand...
Thank you my friend! I will pull the tank replace it the sending unit and filters and flush out all the lines. I appreciate you looking at it for me.
 
To be safe do yall think I should replace the pump too? If there is that much in the carb the pump has to be full of sediments right?
 
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