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Discussion Starter · #1 ·
So I started rebuilding a '79 vintage Q-Jet that was sitting for over 10 years. While disassembling I noticed the secondary butterflies weren't opening. I assumed they were gummed up so I continued the disassembly and soaking. After cleanup they were still stuck shut. I thought I would try taking off the throttle blades and isolate the problem to them being stuck or the shaft. After breaking off the first screw, I researched a tech article in QuadrajetParts and discovered I was supposed to file off the exposed end of the screws before removing. Damn. I then tried to push the blades and they appeared to flex away from the throttle body, so now I'm thinking the shaft is stuck. Before I muck up any more parts, any tips on removing the shaft without inflicting any more damage? TIA... Dan T
 

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Heat is your friend, try to heat the casting genltly. I went thru this few months a go, be carefull.
 

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Search out some Q-Jet builders here. Im not sure you can even get those parts from NAPA or the like anymore. Been over 25 years since I bought a Q-Jet kit.

I would be careful applying heat. I believe Q - Jets are pot metal. Im not really sure how that reacts to each other. Depending on the heat and temp of the heat. Janih did say gently.

Soaking the Q-Jet in a cleaner or mixture of cleaner for a long period of time could help. You would just have to search that out.
 

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I'm sure we can find some parts for Don if need be.
 

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Is it the actual secondaries sticking or the air valve in the top ? I just finished for a boat one where the air valve was sticking. I had to take it apart and run a reamer through the shaft bore to clean it up.

Try soaking yours again with penetrating oil and tap on both ends of the shaft with a small hammer and see if it will break loose.

These guys are a pretty good source for parts:


If you order throttle plate screws make sure you measure yours first. There are two different sizes but they really dont tell you that in their listings.
 

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Discussion Starter · #7 ·
Confirming they are the secondaries. And I did get a kit from Napa before I tore it down. Qjetparts.com is where I saw the info on filing the screws… they have really good tech articles. So regarding the screw… the head and a few threads snapped off. The remaining threads and the mushroomed portion sticking out the other side are intact and seem pretty solid. I’m thinking of just putting a drop of thread locker in the cavity vs. replacing. Yay/nay?
 

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Confirming they are the secondaries. And I did get a kit from Napa before I tore it down. Qjetparts.com is where I saw the info on filing the screws… they have really good tech articles. So regarding the screw… the head and a few threads snapped off. The remaining threads and the mushroomed portion sticking out the other side are intact and seem pretty solid. I’m thinking of just putting a drop of thread locker in the cavity vs. replacing. Yay/nay?
Depend on how brave you are :) What I would do if was not replacing the screws is to put them in with a drop of red loctite then turn them over and with something solid under each screw head take a center punch and give it a good hit right to the center of each screw. Te one where the head broke off has to be replaced, why not just get all 4 new ones ? Too bad you arent closer, I have a bag of the 3-48 screws that I got from McMaster Carr years ago.

I would also say be very careful with heat. The throttle shafts have a teflon (or something) coating on them, at least the newer ones do and I wouldnt want to burn it off.
 

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Confirming they are the secondaries. And I did get a kit from Napa before I tore it down. Qjetparts.com is where I saw the info on filing the screws… they have really good tech articles. So regarding the screw… the head and a few threads snapped off. The remaining threads and the mushroomed portion sticking out the other side are intact and seem pretty solid. I’m thinking of just putting a drop of thread locker in the cavity vs. replacing. Yay/nay?
Can you get a set of small vice grips on the mushroomed section and turn the remaining screw out from the other side?
 

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Good to see there are those still using Quadra Jets.
You got that right, the Q-jets were light years ahead of the AFB carbs for me and way easier to tune.
 

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Dan,
If you arent not in a hurry send me your address and I will throw some screws in an envelope and mail them to you.
 

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Again, good to see there are still people around providing services and parts to what no one wants in the masses. There is a market for that stuff.
 
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Look How much helpful people here, this Forum feels like home. Get the Cliffs book, I have it and it is Super!
 

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64ElcoDan : So I started rebuilding a '79 vintage Q-Jet that was sitting for over 10 years.
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BTW, 1979 was one of the best to rebuild.
It may be an 800 cfm unit. Model "M4M"
 
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An angled front vent tube is always a good sign.
 
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